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Sample records for beam fine focus

  1. Final focus test beam

    International Nuclear Information System (INIS)

    1991-03-01

    This report discusses the following: the Final Focus Test Beam Project; optical design; magnets; instrumentation; magnetic measurement and BPM calibration; mechanical alignment and stabilization; vacuum system; power supplies; control system; radiation shielding and personnel protection; infrastructure; and administration

  2. Laser Beam Focus Analyser

    DEFF Research Database (Denmark)

    Nielsen, Peter Carøe; Hansen, Hans Nørgaard; Olsen, Flemming Ove

    2007-01-01

    the obtainable features in direct laser machining as well as heat affected zones in welding processes. This paper describes the development of a measuring unit capable of analysing beam shape and diameter of lasers to be used in manufacturing processes. The analyser is based on the principle of a rotating...... mechanical wire being swept through the laser beam at varying Z-heights. The reflected signal is analysed and the resulting beam profile determined. The development comprised the design of a flexible fixture capable of providing both rotation and Z-axis movement, control software including data capture...... and finally data analysis based on the ISO approach. The device was calibrated and tested on commercially available laser systems. It showed good reproducibility. It was the target to be able to measure CW lasers with a power up to 200 W, focused down to spot diameters in the range of 10µm. In order...

  3. Focused ion beam technology

    International Nuclear Information System (INIS)

    Gamo, K.

    1993-01-01

    Focussed ion beam (FIB) technology has the advantage of being a maskless process compatible with UHV processing. This makes it attractive for use in in situ processing and has been applied to the fabrication of various mesoscopic structures. The present paper reviews these results whilst putting emphasis on in situ processing by a combined FIB and molecular beam epitaxy system. The typical performance of present FIB systems is also presented. In order to utilize the potential advantages of FIB processing, reduction of damage and improvement of throughput are important, and much effort has been devoted to developing processing techniques which require a reduced dose. The importance of low-energy FIB is discussed. (author)

  4. Ion beam generation and focusing

    International Nuclear Information System (INIS)

    Miller, P.A.; Mendel, C.W.; Swain, D.W.; Goldstein, S.A.

    1975-01-01

    Calculations have shown that efficiently generated and focused ion beams could have significant advantages over electron beams in achieving ignition of inertially-confined thermonuclear fuel. Efficient ion beam generation implies use of a good ion source and suppression of net electron current. Net electron flow can be reduced by allowing electrons to reflex through a highly transparent anode or by use of transverse magnetic fields (either beam self-fields or externally applied fields). Geometric focusing can be achieved if the beam is generated by appropriately shaped electrodes. Experimental results are presented which demonstrate ion beam generation in both reflexing and pinched-flow diodes. Spherically shaped electrodes are used to concentrate a proton beam, and target response to proton deposition is studied

  5. Literature in Focus Beta Beams: Neutrino Beams

    CERN Multimedia

    2009-01-01

    By Mats Lindroos (CERN) and Mauro Mezzetto (INFN Padova, Italy) Imperial Press, 2009 The beta-beam concept for the generation of electron neutrino beams was first proposed by Piero Zucchelli in 2002. The idea created quite a stir, challenging the idea that intense neutrino beams only could be produced from the decay of pions or muons in classical neutrino beams facilities or in future neutrino factories. The concept initially struggled to make an impact but the hard work by many machine physicists, phenomenologists and theoreticians over the last five years has won the beta-beam a well-earned position as one of the frontrunners for a possible future world laboratory for high intensity neutrino oscillation physics. This is the first complete monograph on the beta-beam concept. The book describes both technical aspects and experimental aspects of the beta-beam, providing students and scientists with an insight into the possibilities o...

  6. Plasma lenses for focusing relativistic electron beams

    International Nuclear Information System (INIS)

    Govil, R.; Wheeler, S.; Leemans, W.

    1997-01-01

    The next generation of colliders require tightly focused beams with high luminosity. To focus charged particle beams for such applications, a plasma focusing scheme has been proposed. Plasma lenses can be overdense (plasma density, n p much greater than electron beam density, n b ) or underdense (n p less than 2 n b ). In overdense lenses the space-charge force of the electron beam is canceled by the plasma and the remaining magnetic force causes the electron beam to self-pinch. The focusing gradient is nonlinear, resulting in spherical aberrations. In underdense lenses, the self-forces of the electron beam cancel, allowing the plasma ions to focus the beam. Although for a given beam density, a uniform underdense lens produces smaller focusing gradients than an overdense lens, it produces better beam quality since the focusing is done by plasma ions. The underdense lens can be improved by tapering the density of the plasma for optimal focusing. The underdense lens performance can be enhanced further by producing adiabatic plasma lenses to avoid the Oide limit on spot size due to synchrotron radiation by the electron beam. The plasma lens experiment at the Beam Test Facility (BTF) is designed to study the properties of plasma lenses in both overdense and underdense regimes. In particular, important issues such as electron beam matching, time response of the lens, lens aberrations and shot-to-shot reproducibility are being investigated

  7. Results of Final Focus Test Beam

    Energy Technology Data Exchange (ETDEWEB)

    Walz, Dieter R

    2003-06-13

    The beam experiments of Final Focus Test Beam (FFTB) started in September 1993 at SLAC, and have produced a 1.7 {micro}m x 75 nm spot of 46 GeV electron beam. A number of new techniques involving two nanometer spot-size monitors have been developed. Several beam diagnostic/tuning schemes are applied to achieve and maintain the small spot. This experiment opens the way toward the nanometer world for future linear colliders.

  8. Stability of Periodically Focused Intense Particle Beams

    International Nuclear Information System (INIS)

    Pakter, R.; Rizzato, F. B.

    2001-01-01

    A stability analysis of periodically focused intense particle beams based on the beam envelope equation is performed. We show that (i) the scenario, as the focusing field increases, is not the existence of a single threshold above which stable matched (equilibrium) solutions are absent, as generally believed, but the existence of successive regions of stability interrupted by gaps of instability; (ii) the beam can be focused to tighter radii using new stable matched solutions found for focusing field strengths greater than the previous threshold. Self-consistent simulations validate the findings

  9. Applications of focused ion beams in microelectronics

    International Nuclear Information System (INIS)

    Broughton, C.; Beale, M.I.J.; Deshmukh, V.G.I.

    1986-04-01

    We present the conclusions of the RSRE programme on the application of focused ion beams in microelectronics and review the literature published in this field. We discuss the design and performance of focused beam implanters and the viability of their application to semiconductor device fabrication. Applications in the areas of lithography, direct implantation and micromachining are discussed in detail. Comparisons are made between the use of focused ion beams and existing techniques for these fabrication processes with a strong emphasis placed on the relative throughputs. We present results on a novel spot size measurement technique and the effect of beam heating on resist. We also present the results of studies into implantation passivation of resist to oxygen plasma attack as basis for a dry development lithography scheme. A novel lithography system employing flood electron exposure from a photocathode which is patterned by a focused ion beam which can also be used to repair mask defects is considered. (author)

  10. Foil focusing of relativistic electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Jr., Carl August [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-26

    When an intense relativistic electron beams (IREB) passes through a grounded metal foil, the transverse electric field due to the beam space charge is locally shorted out, and the beam is focused by the magnetic field of its current. The effect can be treated as focusing by a thin lens with first order aberration. Expressions for the focal length and aberration coefficient of the equivalent thin lens are developed in this note. These are then applied to practical examples representative of IREB research at Los Alamos National Laboratory.

  11. Final focus system for high intensity beams

    Directory of Open Access Journals (Sweden)

    Enrique Henestroza

    2005-05-01

    Full Text Available The neutralized transport experiment (NTX at the Heavy Ion Fusion Virtual National Laboratory is exploring the performance of neutralized final-focus systems for high perveance heavy ion beams. The final-focus scenario in a heavy ion fusion driver consists of several large aperture quadrupole magnets followed by a drift section in which the beam space charge is neutralized by a plasma. This beam is required to hit a millimeter-sized target spot at the end of the drift section. The objective of the NTX experiments and associated theory and simulations is to study the various physical mechanisms that determine the final spot size (radius r_{s} at a given distance (f from the end of the last quadrupole. In a fusion driver, f is the standoff distance required to keep the chamber wall and superconducting magnets properly protected. The NTX final quadrupole focusing system produces a converging beam at the entrance to the neutralized drift section where it focuses to a small spot. The final spot is determined by the conditions of the beam entering the quadrupole section, the beam dynamics in the magnetic lattice, and the plasma neutralization dynamics in the drift section. The main issues are the control of emittance growth due to high order fields from magnetic multipoles and image fields. In this paper, we will describe the theoretical and experimental aspects of the beam dynamics in the quadrupole lattice, and how these physical effects influence the final beam size. In particular, we present theoretical and experimental results on the dependence of final spot size on geometric aberrations and perveance.

  12. Centroid motion in periodically focused beams

    International Nuclear Information System (INIS)

    Moraes, J.S.; Pakter, R.; Rizzato, F.B.

    2005-01-01

    The role of the centroid dynamics in the transport of periodically focused particle beams is investigated. A Kapchinskij-Vladimirskij equilibrium distribution for an off-axis beam is derived. It is shown that centroid and envelope dynamics are uncoupled and that unstable regions for the centroid dynamics overlap with previously stable regions for the envelope dynamics alone. Multiparticle simulations validate the findings. The effects of a conducting pipe encapsulating the beam are also investigated. It is shown that the charge induced at the pipe may generate chaotic orbits which can be detrimental to the adequate functioning of the transport mechanism

  13. Focusing an antimatter beam with matter

    CERN Document Server

    CERN. Geneva

    2000-01-01

    An experiment at the Stanford Linear Accelerator Center has recently focused positron beams by means of a plasma lens. This is the first time this process has been observed. The process started with a positron beam from the SLAC PEP-II positron source. This was sent through a damping ring and then accelerated to 28.5 GeV in the SLAC linac with a bunch intensity of 1-2*10/sup 10/. The beam was delivered to the Final Focus Test Beam Facility (FFTB) at a rate of 1 or 10 Hz. At the focal point of the FFTB transport, a special plasma chamber contains a 3 mm diameter pulsed gas nozzle through which either hydrogen or nitrogen gas is "puffed" into the ultrahigh vacuum system at plenum gas pressures up to 75 atm with a discharge time of 800 mu s. The gas is pumped off by a Roots-type pump. On either side of the central chamber are differential pumping sections semi- isolated from each other by thin titanium windows with small (2-5 mm diameter) apertures for the positron beams to pass through. These sections are evacu...

  14. Focused ion beam milling of carbon fibres

    International Nuclear Information System (INIS)

    Huson, Mickey G.; Church, Jeffrey S.; Hillbrick, Linda K.; Woodhead, Andrea L.; Sridhar, Manoj; Van De Meene, Allison M.L.

    2015-01-01

    A focused ion beam has been used to mill both individual carbon fibres as well as fibres in an epoxy composite, with a view to preparing flat surfaces for nano-indentation. The milled surfaces have been assessed for damage using scanning probe microscopy nano-indentation and Raman micro-probe analysis, revealing that FIB milling damages the carbon fibre surface and covers surrounding areas with debris of disordered carbon. The debris is detected as far as 100 μm from the milling site. The energy of milling as well as the orientation of the beam was varied and shown to have an effect when assessed by Raman spectroscopy. - Highlights: • Focused ion beam (FIB) milling was used to mill flat surfaces on carbon fibres. • Raman spectroscopy showed amorphous carbon was generated during FIB milling. • The amorphous debris is detected as far as 100 μm from the milling site. • This surface degradation was confirmed by nano-indentation experiments.

  15. Ion Beam Extraction by Discrete Ion Focusing

    DEFF Research Database (Denmark)

    2010-01-01

    An apparatus (900) and methods are disclosed for ion beam extraction. In an implementation, the apparatus includes a plasma source (or plasma) (802) and an ion extractor (804). The plasma source is adapted to generate ions and the ion extractor is immersed in the plasma source to extract a fraction...... of the generated ions. The ion extractor is surrounded by a space charge (810) formed at least in part by the extracted ions. The ion extractor includes a biased electrode (806) forming an interface with an insulator (808). The interface is customized to form a strongly curved potential distribution (812......) in the space-charge surrounding the ion extractor. The strongly curved potential distribution focuses the extracted ions towards an opening (814) on a surface of the biased electrode thereby resulting in an ion beam....

  16. Focused Ion Beam Fabrication of Microelectronic Structures

    Science.gov (United States)

    1990-12-01

    Focused Ion Beams and Applications, Portland, OR Dec. 1990. 28. Y.L. Wang, H. Temkin , L.R. Harriott, R.A. Logan, and T. Tanban-Ek. Appi. Phys. Lett. 571864...been used.(2 8 ,3 0) In addition, in-situ measurement of adsorption rates and deposition rates can be readily obtained by using a quartz crystal...not well understood at the present time. Possible rate limiting steps in this process " .. are adsorption of molecules, decomposition of molecules, and

  17. An electromagnetically focused electron beam line source

    International Nuclear Information System (INIS)

    Iqbal, Munawar; Masood, Khalid; Rafiq, Mohammad; Chaudhary, Maqbool A.; Aleem, Fazal-e-

    2003-01-01

    A directly heated thermionic electron beam source was constructed. A tungsten wire of length 140 mm with diameter 0.9 mm was used as a cathode. An emission current of 5000 mA was achieved at an input heating power of 600 W. Cathode to anode distance of 6 mm with acceleration voltage of 10 kV was used. A uniform external magnetic field of 50 G was employed to obtain a well-focused electron beam at a deflection of 180 deg., with cathode to work site distance of 130 mm. Dimensions of the beam (1.25x120 mm) recorded at the work site were found to be in good agreement with the designed length of cathode. The deformation of the cathode was overcome by introducing a spring action mechanism, which gives uniform emission current density throughout the emission surface. We have achieved the saturation limit of the designed source resulting in smooth and swift operation of the gun for many hours (10-15 h continuously). The design of gun is so simple that it can accommodate longer cathodes for obtaining higher emission values. This gun has made it possible to coat large substrate surfaces at much faster evaporation rate at lower cost. It can also be useful in large-scale vacuum metallurgy plants for melting, welding and heat treatment

  18. Three dimensional analysis of the pore space in fine-grained Boom Clay, using BIB-SEM (broad-ion beam scanning electron microscopy), combined with FIB (focused ion-beam) serial cross-sectioning, pore network modeling and Wood's metal injection

    Science.gov (United States)

    Hemes, Susanne; Klaver, Jop; Desbois, Guillaume; Urai, Janos

    2014-05-01

    The Boom Clay is, besides the Ypresian clays, one of the potential host rock materials for radioactive waste disposal in Belgium (Gens et al., 2003; Van Marcke & Laenen, 2005; Verhoef et al., 2011). To access parameters, which are relevant for the diffusion controlled transport of radionuclides in the material, such as porosity, pore connectivity and permeability, it is crucial to characterize the pore space at high resolution (nm-scale) and in 3D. Focused-ion-beam (FIB) serial cross-sectioning in combination with high resolution scanning electron microscopy (SEM), pore network modeling, Wood's metal injection and broad-ion-beam (BIB) milling, constitute a superior set of methods to characterize the 3D pore space in fine-grained, clayey materials, down to the nm-scale resolution. In the present study, we identified characteristic 3D pore space morphologies, determined the 3D volume porosity of the material and applied pore network extraction modeling (Dong and Blunt, 2009), to access the connectivity of the pore space and to discriminate between pore bodies and pore throats. Moreover, we used Wood's metal injection (WMI) in combination with BIB-SEM imaging to assess the pore connectivity at a larger scale and even higher resolution. The FIB-SEM results show a highly (~ 90 %) interconnected pore space in Boom Clay, down to the resolution of ~ 3E+03 nm³ (voxel-size), with a total volume porosity of ~ 20 %. Pore morphologies of large (> 5E+08 nm³), highly interconnected pores are complex, with high surface area to volume ratios (shape factors G ~ 0.01), whereas small (< 1E+06 nm³), often isolated pores are much more compact and show higher shape factors (G) up to 0.03. WMI in combination with BIB-SEM, down to a resolution of ~ 50 nm² pixel-size, indicates an interconnected porosity fraction of ~ 80 %, of a total measured 2D porosity of ~ 20 %. Determining and distinguishing between pore bodies and pore throats enables us to compare 3D FIB-SEM pore

  19. Funnel cone for focusing intense ion beams on a target

    International Nuclear Information System (INIS)

    Bieniosek, F.M.; Henestroza, E.; Ni, P.

    2009-01-01

    We describe a funnel cone for concentrating an ion beam on a target. The cone utilizes the reflection characteristic of ion beams on solid walls to focus the incident beam andincrease beam intensity on target. The cone has been modeled with the TRIM code. A prototype has been tested and installed for use in the 350-keV K+ NDCX target chamber.

  20. Characteristics of selective deposition of metal organic films using focused ion beams

    International Nuclear Information System (INIS)

    Gamo, Kenji; Takakura, Nobuyuki; Takehara, Daisuke; Namba, Susumu

    1984-01-01

    50 keV Ar + or 35 keV focused Ga + beam were irradiated in a trimethyl aluminum atmosphere to provide a detailed characterization of maskless deposition. It was found from Auger electron spectroscopy that deposited films contain oxygen, carbon, aluminum and fluorine. The film thickness increased linearly with increasing a dose and the deposition rate was 10-20 nm/(10 16 ions/cm 2 ). A 0.5μm wide fine pattern which reflects a beam profile was formed by using focused Ga + beam. (author)

  1. Monte Carlo evaluation of magnetically focused proton beams for radiosurgery

    Science.gov (United States)

    McAuley, Grant A.; Heczko, Sarah L.; Nguyen, Theodore T.; Slater, James M.; Slater, Jerry D.; Wroe, Andrew J.

    2018-03-01

    The purpose of this project is to investigate the advantages in dose distribution and delivery of proton beams focused by a triplet of quadrupole magnets in the context of potential radiosurgery treatments. Monte Carlo simulations were performed using various configurations of three quadrupole magnets located immediately upstream of a water phantom. Magnet parameters were selected to match what can be commercially manufactured as assemblies of rare-earth permanent magnetic materials. Focused unmodulated proton beams with a range of ~10 cm in water were target matched with passive collimated beams (the current beam delivery method for proton radiosurgery) and properties of transverse dose, depth dose and volumetric dose distributions were compared. Magnetically focused beams delivered beam spots of low eccentricity to Bragg peak depth with full widths at the 90% reference dose contour from ~2.5 to 5 mm. When focused initial beam diameters were larger than matching unfocused beams (10 of 11 cases) the focused beams showed 16%–83% larger peak-to-entrance dose ratios and 1.3 to 3.4-fold increases in dose delivery efficiency. Peak-to-entrance and efficiency benefits tended to increase with larger magnet gradients and larger initial diameter focused beams. Finally, it was observed that focusing tended to shift dose in the water phantom volume from the 80%–20% dose range to below 20% of reference dose, compared to unfocused beams. We conclude that focusing proton beams immediately upstream from tissue entry using permanent magnet assemblies can produce beams with larger peak-to-entrance dose ratios and increased dose delivery efficiencies. Such beams could potentially be used in the clinic to irradiate small-field radiosurgical targets with fewer beams, lower entrance dose and shorter treatment times.

  2. Beam focusing in reflections from flat subwavelength diffraction gratings

    OpenAIRE

    Cheng, Yu Chieh; Redondo, Javier; Staliunas, Kestutis

    2014-01-01

    We predict that narrow beams, reflecting from flat subwavelength diffraction gratings, can focus. The effect is shown for the beams of electromagnetic radiation; however, it should be observable for beams of waves of arbitrary nature (microwaves, surface plasmons, and acoustic and mechanical waves). We present analytical estimations of the focusing performance obtained by multiple scattering calculations and demonstrate the focusing effect numerically for an optical system (reflections from a...

  3. Plasma focusing and diagnosis of high energy particle beams

    International Nuclear Information System (INIS)

    Chen, Pisin.

    1990-09-01

    Various novel concepts of focusing and diagnosis of high energy charged particle beams, based on the interaction between the relativistic particle beam and the plasma, are reviewed. This includes overdense thin plasma lenses, and (underdense) adiabatic plasma lens, and two beam size monitor concepts. In addition, we introduce another mechanism for measuring flat beams based on the impulse received by heavy ions in an underdense plasma. Theoretical investigations show promise of focusing and diagnosing beams down to sizes where conventional methods are not possible to provide. 21 refs

  4. Development of a focused ion beam micromachining system

    Energy Technology Data Exchange (ETDEWEB)

    Pellerin, J.G.; Griffis, D.; Russell, P.E.

    1988-12-01

    Focused ion beams are currently being investigated for many submicron fabrication and analytical purposes. An FIB micromachining system consisting of a UHV vacuum system, a liquid metal ion gun, and a control and data acquisition computer has been constructed. This system is being used to develop nanofabrication and nanomachining techniques involving focused ion beams and scanning tunneling microscopes.

  5. Formation of focused laser beams with a hollow metal cone

    International Nuclear Information System (INIS)

    Wu, Pinghui; Pan, Quanjun; Wei, Kaihua; Wu, Bo; Jiang, Peipei; Li, Jia; Peng, Xuefeng

    2015-01-01

    A hollow metal cone is designed to focus a laser beam into a tiny highly localized beam spot. The finite difference time domain method has been introduced to investigate the beam focusing effect along the propagation direction. Without considering the laser–plasma nonlinear interaction, the numerical calculation results show that a focal spot with a full width at half maximum of ∼0.7λ at greatly enhanced intensity and a depth of focus of ∼3λ can be achieved. In addition, the influences of cone angle, cone tip size, metal materials, sidewall thickness and incident wavelength on the focusing properties are analyzed in detail. (letter)

  6. A high resolution hand-held focused beam profiler

    Science.gov (United States)

    Zapata-Farfan, J.; Garduño-Mejía, J.; Rosete-Aguilar, M.; Ascanio, G.; Román-Moreno, C. J.

    2017-05-01

    The shape of a beam is important in any laser application and depending on the final implementation, there exists a preferred one which is defined by the irradiance distribution.1 The energy distribution (or laser beam profile) is an important parameter in a focused beam, for instance, in laser cut industry, where the beam shape determines the quality of the cut. In terms of alignment and focusing, the energy distribution also plays an important role since the system must be configured in order to reduce the aberration effects and achieve the highest intensity. Nowadays a beam profiler is used in both industry and research laboratories with the aim to characterize laser beams used in free-space communications, focusing and welding, among other systems. The purpose of the profile analyzers is to know the main parameters of the beam, to control its characteristics as uniformity, shape and beam size as a guide to align the focusing system. In this work is presented a high resolution hand-held and compact design of a beam profiler capable to measure at the focal plane, with covered range from 400 nm to 1000 nm. The detection is reached with a CMOS sensor sized in 3673.6 μm x 2738.4 μm which acquire a snap shot of the previously attenuated focused beam to avoid the sensor damage, the result is an image of beam intensity distribution, which is digitally processed with a RaspberryTMmodule gathering significant parameters such as beam waist, centroid, uniformity and also some aberrations. The profiler resolution is 1.4 μm and was probed and validated in three different focusing systems. The spot sizes measurements were compared with the Foucault knife-edge test.

  7. Plasma lens experiments at the Final Focus Test Beam

    International Nuclear Information System (INIS)

    Barletta, B.; Chattopadhyay, S.; Chen, P.

    1993-04-01

    We intend to carry out a series of plasma lens experiments at the Final Focus Test Beam facility at SLAC. These experiments will be the first to study the focusing of particle beams by plasma focusing devices in the parameter regime of interest for high energy colliders, and is expected to lead to plasma lens designs capable of unprecedented spot sizes. Plasma focusing of positron beams will be attempted for the first time. We will study the effects of lens aberrations due to various lens imperfections. Several approaches will be applied to create the plasma required including laser ionization and beam ionization of a working gas. At an increased bunch population of 2.5 x 10 10 , tunneling ionization of a gas target by an electron beam -- an effect which has never been observed before -- should be significant. The compactness of our device should prove to be of interest for applications at the SLC and the next generation linear colliders

  8. Plasma lens experiments at the Final Focus Test Beam

    Energy Technology Data Exchange (ETDEWEB)

    Barletta, B. [California Univ., Los Angeles, CA (United States)]|[Lawrence Berkeley Lab., CA (United States); Chattopadhyay, S. [Lawrence Berkeley Lab., CA (United States); Chen, P. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)] [and others

    1993-04-01

    We intend to carry out a series of plasma lens experiments at the Final Focus Test Beam facility at SLAC. These experiments will be the first to study the focusing of particle beams by plasma focusing devices in the parameter regime of interest for high energy colliders, and is expected to lead to plasma lens designs capable of unprecedented spot sizes. Plasma focusing of positron beams will be attempted for the first time. We will study the effects of lens aberrations due to various lens imperfections. Several approaches will be applied to create the plasma required including laser ionization and beam ionization of a working gas. At an increased bunch population of 2.5 {times} 10{sup 10}, tunneling ionization of a gas target by an electron beam -- an effect which has never been observed before -- should be significant. The compactness of our device should prove to be of interest for applications at the SLC and the next generation linear colliders.

  9. Review of tolerances at the Final Focus Test Beam

    International Nuclear Information System (INIS)

    Bulos, F.; Burke, D.; Helm, R.; Irwin, J.; Roy, G.; Yamamoto, N.

    1991-01-01

    The authors review the tolerances associated with the Final Focus Test Beam (FFTB). The authors have computed the acceptability window of the input beam for orbit jitter, emittance beta functions mismatch, incoming dispersion and coupling; tolerances on magnet alignment, strength and multipole content; and the initial tuneability capture of the line

  10. Review of tolerances at the Final Focus Test Beam

    International Nuclear Information System (INIS)

    Bulos, F.; Burke, D.; Helm, R.; Irwin, J.; Roy, G.; Yamamoto, N.

    1991-05-01

    We review the tolerances associated with the Final Focus Test Beam (FFTB). We have computed the acceptability window of the input beam for orbit jitter, emittance beta functions mismatch, incoming dispersion and coupling; tolerances on magnet alignment, strength and multipole content; and the initial tuneability capture of the line. 2 refs., 1 fig

  11. Structuring of silicon with low energy focused ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Nebiker, P.W.; Doebeli, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Muehle, R. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-09-01

    The defect production in silicon induced by focused ion beam irradiation as a function of energy and projectile mass has been investigated and compared to the measured sputter yield. The aim was to find optimal beam parameters for the structuring of semiconductors with a minimum amount of defects produced per removed atom. (author) 2 figs., 2 refs.

  12. Focused Ion Beam Nano-structuring for Applications in Photonics

    NARCIS (Netherlands)

    Ay, F.; de Ridder, R.M.; Pollnau, Markus

    2010-01-01

    To date, nano- and micro-structuring has commonly been implemented by a combination of specifically optimized processes of electron-beam lithography and reactive ion etching, thus limiting the range of materials that can be structured to only a few. In this talk we will introduce focused ion beam

  13. Electrostatic plasma lens for focusing negatively charged particle beams.

    Science.gov (United States)

    Goncharov, A A; Dobrovolskiy, A M; Dunets, S M; Litovko, I V; Gushenets, V I; Oks, E M

    2012-02-01

    We describe the current status of ongoing research and development of the electrostatic plasma lens for focusing and manipulating intense negatively charged particle beams, electrons, and negative ions. The physical principle of this kind of plasma lens is based on magnetic isolation electrons providing creation of a dynamical positive space charge cloud in shortly restricted volume propagating beam. Here, the new results of experimental investigations and computer simulations of wide-aperture, intense electron beam focusing by plasma lens with positive space charge cloud produced due to the cylindrical anode layer accelerator creating a positive ion stream towards an axis system is presented.

  14. Staphylococcal methicillin resistance: fine focus on folds and functions.

    Science.gov (United States)

    Mallorquí-Fernández, Goretti; Marrero, Aniebrys; García-Piquè, Sonia; García-Castellanos, Raquel; Gomis-Rüth, F Xavier

    2004-06-01

    Globalisation has entailed a massive increase in trade and human mobility facilitating the rapid spread of infectious agents, including those that are drug resistant. A particularly serious threat to human health is posed by methicillin-resistant staphylococcal strains which have acquired molecular mechanisms to evade the action of beta-lactam antibiotics (BLAs). Full expression of high-level methicillin resistance involves a complex network of molecules and depends primarily on sufficient expression of a penicillin-binding protein with low sensitivity towards BLAs. Other factors include the fine-tuned regulation of autolytic activity of cell-wall components, as well as an optimal rate of peptidoglycan precursor formation and a highly specific peptidoglycan precursor structure. Three-dimensional structural data are available on several of the pieces involved in the jigsaw puzzle and provide a molecular basis for the understanding of methicillin resistance and for the design of new therapeutic strategies.

  15. Beam shape coefficients of the most general focused Gaussian laser beam for light scattering applications

    International Nuclear Information System (INIS)

    Lock, James A.

    2013-01-01

    The vector wave equation for electromagnetic waves, when subject to a number of constraints corresponding to propagation of a monochromatic beam, reduces to a pair of inhomogeneous differential equations describing the transverse electric and transverse magnetic polarized beam components. These differential equations are solved analytically to obtain the most general focused Gaussian beam to order s 4 , where s is the beam confinement parameter, and various properties of the most general Gaussian beam are then discussed. The radial fields of the most general Gaussian beam are integrated to obtain the on-axis beam shape coefficients of the generalized Lorenz–Mie theory formalism of light scattering. The beam shape coefficients are then compared with those of the localized Gaussian beam model and the Davis–Barton fifth-order symmetrized beam. -- Highlights: ► Derive the differential equation for the most general Gaussian beam. ► Solve the differential equation for the most general Gaussian beam. ► Determine the properties of the most general Gaussian beam. ► Determine the beam shape coefficients of the most general Gaussian beam

  16. Auto-focusing accelerating hyper-geometric laser beams

    International Nuclear Information System (INIS)

    Kovalev, A A; Kotlyar, V V; Porfirev, A P

    2016-01-01

    We derive a new solution to the paraxial wave equation that defines a two-parameter family of three-dimensional structurally stable vortex annular auto-focusing hyper-geometric (AH) beams, with their complex amplitude expressed via a degenerate hyper-geometric function. The AH beams are found to carry an orbital angular momentum and be auto-focusing, propagating on an accelerating path toward a focus, where the annular intensity pattern is ‘sharply’ reduced in diameter. An explicit expression for the complex amplitude of vortex annular auto-focusing hyper-geometric-Gaussian beams is derived. The experiment has been shown to be in good agreement with theory. (paper)

  17. Electrostatic quadrupole array for focusing parallel beams of charged particles

    International Nuclear Information System (INIS)

    Brodowski, J.

    1982-01-01

    An array of electrostatic quadrupoles, capable of providing strong electrostatic focusing simultaneously on multiple beams, is easily fabricated from a single array element comprising a support rod and multiple electrodes spaced at intervals along the rod. The rods are secured to four terminals which are isolated by only four insulators. This structure requires bias voltage to be supplied to only two terminals and eliminates the need for individual electrode bias and insulators, as well as increases life by eliminating beam plating of insulators

  18. Cobalt alloy ion sources for focused ion beam implantation

    Energy Technology Data Exchange (ETDEWEB)

    Muehle, R.; Doebeli, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Zimmermann, P. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-09-01

    Cobalt alloy ion sources have been developed for silicide formation by focused ion beam implantation. Four eutectic alloys AuCo, CoGe, CoY and AuCoGe were produced by electron beam welding. The AuCo liquid alloy ion source was investigated in detail. We have measured the emission current stability, the current-voltage characteristics, and the mass spectrum as a function of the mission current. (author) 1 fig., 2 refs.

  19. Scattering of an ion beam by charged fine particles with Coulomb force

    International Nuclear Information System (INIS)

    Amemiya, H.; Nakamura, Y.

    2002-01-01

    Fine particles satisfying critical limits act as Coulomb forces and scatter charged particles like beams due to the long-range force. Otherwise, fine particles behave as tiny probes. The energy loss and broadening rates of an ion beam by particles having Coulomb fields are investigated where the Coulomb logarithm is taken as a variable. Dependence of the energy loss and broadening on the plasma density, dust charge and beam energy is obtained. A method for measuring the dust surface charge is also given

  20. Comprehensive study of beam focusing by crystal devices

    Science.gov (United States)

    Scandale, W.; Arduini, G.; Cerutti, F.; Garattini, M.; Gilardoni, S.; Masi, A.; Mirarchi, D.; Montesano, S.; Petrucci, S.; Redaelli, S.; Rossi, R.; Breton, D.; Burmistrov, L.; Dubos, S.; Maalmi, J.; Natochii, A.; Puill, V.; Stocchi, A.; Sukhonos, D.; Bagli, E.; Bandiera, L.; Guidi, V.; Mazzolari, A.; Romagnoni, M.; Murtas, F.; Addesa, F.; Cavoto, G.; Iacoangeli, F.; Galluccio, F.; Afonin, A. G.; Bulgakov, M. K.; Chesnokov, Yu. A.; Durum, A. A.; Maisheev, V. A.; Sandomirskiy, Yu. E.; Yanovich, A. A.; Kolomiets, A. A.; Kovalenko, A. D.; Taratin, A. M.; Smirnov, G. I.; Denisov, A. S.; Gavrikov, Yu. A.; Ivanov, Yu. M.; Lapina, L. P.; Malyarenko, L. G.; Skorobogatov, V. V.; Auzinger, G.; James, T.; Hall, G.; Pesaresi, M.; Raymond, M.

    2018-01-01

    This paper is devoted to an experimental study of focusing and defocusing positively charged particle beams with the help of specially bent single crystals. Four crystals have been fabricated for this purpose. The studies have been performed at the CERN SPS in 400 GeV /c proton and 180 GeV /c pion beams. The results of measurements of beam envelopes are presented. The rms size of the horizontal profile at the focus was 5-8 times smaller than at the exit of the crystals. The measured focal lengths were 4-21 m. The results of measurements are in good agreement with calculations. Possible applications of focusing crystals in present and future high energy accelerators are discussed.

  1. Multi-focus beam shaping of high power multimode lasers

    Science.gov (United States)

    Laskin, Alexander; Volpp, Joerg; Laskin, Vadim; Ostrun, Aleksei

    2017-08-01

    Beam shaping of powerful multimode fiber lasers, fiber-coupled solid-state and diode lasers is of great importance for improvements of industrial laser applications. Welding, cladding with millimetre scale working spots benefit from "inverseGauss" intensity profiles; performance of thick metal sheet cutting, deep penetration welding can be enhanced when distributing the laser energy along the optical axis as more efficient usage of laser energy, higher edge quality and reduction of the heat affected zone can be achieved. Building of beam shaping optics for multimode lasers encounters physical limitations due to the low beam spatial coherence of multimode fiber-coupled lasers resulting in big Beam Parameter Products (BPP) or M² values. The laser radiation emerging from a multimode fiber presents a mixture of wavefronts. The fiber end can be considered as a light source which optical properties are intermediate between a Lambertian source and a single mode laser beam. Imaging of the fiber end, using a collimator and a focusing objective, is a robust and widely used beam delivery approach. Beam shaping solutions are suggested in form of optics combining fiber end imaging and geometrical separation of focused spots either perpendicular to or along the optical axis. Thus, energy of high power lasers is distributed among multiple foci. In order to provide reliable operation with multi-kW lasers and avoid damages the optics are designed as refractive elements with smooth optical surfaces. The paper presents descriptions of multi-focus optics as well as examples of intensity profile measurements of beam caustics and application results.

  2. An automatic beam focusing system for MeV protons

    Science.gov (United States)

    Udalagama, C. N. B.; Bettiol, A. A.; van Kan, J. A.; Teo, E. J.; Breese, M. B. H.; Osipowicz, T.; Watt, F.

    2005-04-01

    An automatic focusing system for MeV protons has been developed. The focusing system utilises rapid real time proton induced secondary electron imaging of a calibration grid coupled with a modified Gaussian fit in order to take into account the enhanced secondary electron signal from the calibration grid edge. The focusing system has been successfully applied to MeV protons focused using a coupled triplet configuration of magnetic quadrupole lenses (Oxford triplet). Automatic beam focusing of a coarse beamspot of approximately (5 × 3.5) micrometres in the X and Y directions to a sub-micrometre beamspot of approximately (0.7 × 0.6) micrometers was achieved at a beam current of about 50 pA.

  3. An automatic beam focusing system for MeV protons

    International Nuclear Information System (INIS)

    Udalagama, C.N.B.; Bettiol, A.A.; Kan, J.A. van; Teo, E.J.; Breese, M.B.H.; Osipowicz, T.; Watt, F.

    2005-01-01

    An automatic focusing system for MeV protons has been developed. The focusing system utilises rapid real time proton induced secondary electron imaging of a calibration grid coupled with a modified Gaussian fit in order to take into account the enhanced secondary electron signal from the calibration grid edge. The focusing system has been successfully applied to MeV protons focused using a coupled triplet configuration of magnetic quadrupole lenses (Oxford triplet). Automatic beam focusing of a coarse beamspot of approximately (5 x 3.5) micrometres in the X and Y directions to a sub-micrometre beamspot of approximately (0.7 x 0.6) micrometers was achieved at a beam current of about 50 pA

  4. Design of Extended Depth-of-Focus Laser Beams Using Orthogonal Beam Expansions

    Directory of Open Access Journals (Sweden)

    Leonard Bergstein

    2005-06-01

    Full Text Available Laser beams with extended depth of focus have many practical applications, such as scanning printed bar codes. Previous work has concentrated on synthesizing such beams by approximating the nondiffracting Bessel beam solution to the wave equation. In this paper, we introduce an alternate novel synthesis method that is based on maintaining a minimum MTF value (contrast over the largest possible distance. To achieve this, the coefficients of an orthogonal beam expansion are sequentially optimized to this criterion. One of the main advantages of this method is that it can be easily generalized to noncircularly symmetrical beams by the appropriate choice of the beam expansion basis functions. This approach is found to be very useful for applications that involve scanning of the laser beam.

  5. High energy focused ion beam lithography using P-beam writing

    International Nuclear Information System (INIS)

    Glass, Gary A.; Rout, Bibhudutta; Dymnikov, Alexander D.; Greco, Richard R.; Kamal, Mithun; Reinhardt, James R.; Peeples, John A.

    2005-01-01

    The term 'P-beam writing' is used to describe the technique of using focused high energy proton microbeams for micro or nanofabrication applications. The P-beam technique can be used to rapidly fabricate three-dimensional, high aspect ratio microstructures in a variety of materials without the use of masks and it is proving to be a versatile lithographic method. Recent developments in the application P-beam writing of microstructures at the Louisiana Accelerator Center are presented

  6. Experimental verification of focusability of coherent annular laser beams

    Science.gov (United States)

    Astadjov, Dimo N.; Prakash, Om

    2013-03-01

    Experiments of focusing coherent laser beams being diffracted on annular aperture are carried out in order to verify issues of a two-dimensional Fast Fourier Transform simulation of coherent pure (dark) annular flat beams done and published before. The beam pattern at focal plane (aka the far-field pattern) is a prominent central peak and faint concentrical rings around it. In the course of simulation we calculate the fraction of the central peak power to the whole power of beam that gives a notion of power spread within the focal spot. This fraction is a function of beam annularity i.e. `inside diameter /outside diameter' ratio. The experimentally-measured dependence of the central peak power to the whole power of beam versus the annularity of pure annular laser beams was the major target of the report. The purpose was to verify experimentally the issues of our earlier simulation. We found that from the five experimental points four of them are within 16% error as to the simulated dependence which is tolerable in such a measurement.

  7. Production of a helium beam in a focused ion beam machine using an electron beam ion trap

    International Nuclear Information System (INIS)

    Ullmann, F.; Grossmann, F.; Ovsyannikov, V. P.; Gierak, J.; Zschornack, G.

    2007-01-01

    Gallium liquid-metal ion sources that have been introduced in the late 1970s have allowed the development of a new class of micro- and nanofabrication tools collectively denominated as focused ion beam (FIB) machines. To investigate the potential of a helium beam in such a FIB instrument the authors have tested a room-temperature electron beam ion trap coupled with a high resolution FIB machine. In this letter they present their first results in target imaging using a helium beam with a resolution that allows to account for a beam diameter in the submicrometer range

  8. Expanded studies of linear collider final focus systems at the Final Focus Test Beam

    Energy Technology Data Exchange (ETDEWEB)

    Tenenbaum, Peter Gregory [Stanford Univ., CA (United States)

    1995-12-01

    In order to meet their luminosity goals, linear colliders operating in the center-of-mass energy range from 3,50 to 1,500 GeV will need to deliver beams which are as small as a few Manometers tall, with x:y aspect ratios as large as 100. The Final Focus Test Beam (FFTB) is a prototype for the final focus demanded by these colliders: its purpose is to provide demagnification equivalent to those in the future linear collider, which corresponds to a focused spot size in the FFTB of 1.7 microns (horizontal) by 60 manometers (vertical). In order to achieve the desired spot sizes, the FFTB beam optics must be tuned to eliminate aberrations and other errors, and to ensure that the optics conform to the desired final conditions and the measured initial conditions of the beam. Using a combination of incoming-beam diagnostics. beam-based local diagnostics, and global tuning algorithms, the FFTB beam size has been reduced to a stable final size of 1.7 microns by 70 manometers. In addition, the chromatic properties of the FFTB have been studied using two techniques and found to be acceptable. Descriptions of the hardware and techniques used in these studies are presented, along with results and suggestions for future research.

  9. Expanded studies of linear collider final focus systems at the Final Focus Test Beam

    International Nuclear Information System (INIS)

    Tenenbaum, P.G.

    1995-12-01

    In order to meet their luminosity goals, linear colliders operating in the center-of-mass energy range from 3,50 to 1,500 GeV will need to deliver beams which are as small as a few Manometers tall, with x:y aspect ratios as large as 100. The Final Focus Test Beam (FFTB) is a prototype for the final focus demanded by these colliders: its purpose is to provide demagnification equivalent to those in the future linear collider, which corresponds to a focused spot size in the FFTB of 1.7 microns (horizontal) by 60 manometers (vertical). In order to achieve the desired spot sizes, the FFTB beam optics must be tuned to eliminate aberrations and other errors, and to ensure that the optics conform to the desired final conditions and the measured initial conditions of the beam. Using a combination of incoming-beam diagnostics. beam-based local diagnostics, and global tuning algorithms, the FFTB beam size has been reduced to a stable final size of 1.7 microns by 70 manometers. In addition, the chromatic properties of the FFTB have been studied using two techniques and found to be acceptable. Descriptions of the hardware and techniques used in these studies are presented, along with results and suggestions for future research

  10. Spatial mode cleaning in radically asymmetric strongly focused laser beams

    Science.gov (United States)

    Heins, Alan M.; Guo, Chunlei

    2013-12-01

    We demonstrate that a femtosecond laser pulse strongly focused in air can produce a highly symmetric damage pattern on glass. This damage pattern contains a series of near-perfect radial rings, with diameters much larger than the predicted focal spot diameter. These rings disappear when the experiment is conducted in vacuum, indicating atmospheric involvement. Surprisingly, the shape and size of the rings seem to be nearly independent of the shape of the generating laser beam, showing dramatic spatial mode cleaning. A "half moon" initial laser mode created by obscuring one side of the round beam produces rings of similar quality to those obtained with the unclipped beam. While spatial mode cleaning has previously been reported in filaments, this is the most dramatic demonstration of the effect that we are aware of. We argue that the effect is due primarily to ionization, in contrast to studies in longer filaments that attribute it to self-focusing.

  11. Laser focusing of high-energy charged-particle beams

    International Nuclear Information System (INIS)

    Channell, P.J.

    1986-01-01

    It is shown that laser focusing of high-energy charged-particle beams using the inverse Cherenkov effect is well suited for applications with large linear colliders. Very high gradient (>0.5 MG/cm) lenses result that can be added sequentially without AG cancellation. These lenses are swell understood, have small geometric aberrations, and offer the possibility of correlating phase and energy aberrations to produce an achromatic final focus

  12. Thermoacoustic focusing lens by symmetric Airy beams with phase manipulations

    Science.gov (United States)

    Liu, Chen; Xia, Jian-Ping; Sun, Hong-Xiang; Yuan, Shou-Qi

    2017-12-01

    We report the realization of broadband acoustic focusing lenses based on two symmetric thermoacoustic phased arrays of Airy beams, in which the units of thermoacoustic phase control are designed by employing air with different temperatures surrounded by rigid insulated boundaries and thermal insulation films. The phase delays of the transmitted and reflected units could cover a whole 2π interval, which arises from the change of the sound velocity of air induced by the variation of the temperature. Based on the units of phase control, we design the transmitted and reflected acoustic focusing lenses with two symmetric Airy beams, and verify the high self-healing focusing characteristic and the feasibility of the thermal insulation films. Besides, the influences of the bending angle of the Airy beam on the focusing performance are discussed in detail. The proposed acoustic lens has advantages of broad bandwidth (about 4.8 kHz), high focusing performance, self-healing feature, and simple structure, which enable it to provide more schemes for acoustic focusing. It has excellent potential applications in acoustic devices.

  13. Cavity-enhanced photoionization of an ultracold rubidium beam for application in focused ion beams

    Science.gov (United States)

    ten Haaf, G.; Wouters, S. H. W.; Mutsaers, P. H. A.; Vredenbregt, E. J. D.

    2017-11-01

    A two-step photoionization strategy of an ultracold rubidium beam for application in a focused ion beam instrument is analyzed and implemented. In this strategy the atomic beam is partly selected with an aperture after which the transmitted atoms are ionized in the overlap of a tightly cylindrically focused excitation laser beam and an ionization laser beam whose power is enhanced in a build-up cavity. The advantage of this strategy, as compared to without the use of a build-up cavity, is that higher ionization degrees can be reached at higher currents. Optical Bloch equations including the photoionization process are used to calculate what ionization degree and ionization position distribution can be reached. Furthermore, the ionization strategy is tested on an ultracold beam of 85Rb atoms. The beam current is measured as a function of the excitation and ionization laser beam intensity and the selection aperture size. Although details are different, the global trends of the measurements agree well with the calculation. With a selection aperture diameter of 52 μ m , a current of (170 ±4 ) pA is measured, which according to calculations is 63% of the current equivalent of the transmitted atomic flux. Taking into account the ionization degree the ion beam peak reduced brightness is estimated at 1 ×107 A/(m2sr eV ).

  14. Molecule-by-Molecule Writing Using a Focused Electron Beam

    DEFF Research Database (Denmark)

    Van Dorp, Willem F.; Zhang, Xiaoyan; Feringa, Ben L.

    2012-01-01

    atoms also be written with an electron beam? We verify this with focused electron-beam-induced deposition (FEBID), a direct-write technique that has the current record for the smallest feature written by (electron) optical lithography. We show that the deposition of an organometallic precursor...... on graphene can be followed molecule-by-molecule with FEBID. The results show that mechanisms that are inherent to the process inhibit a further increase in control over the process. Hence, our results present the resolution limit of (electron) optical lithography techniques. The writing of isolated...

  15. Fundamental limits to imaging resolution for focused ion beams

    International Nuclear Information System (INIS)

    Orloff, J.; Swanson, L.W.; Utlaut, M.

    1996-01-01

    This article investigates the limitations on the formation of focused ion beam images from secondary electrons. We use the notion of the information content of an image to account for the effects of resolution, contrast, and signal-to-noise ratio and show that there is a competition between the rate at which small features are sputtered away by the primary beam and the rate of collection of secondary electrons. We find that for small features, sputtering is the limit to imaging resolution, and that for extended small features (e.g., layered structures), rearrangement, redeposition, and differential sputtering rates may limit the resolution in some cases. copyright 1996 American Vacuum Society

  16. Effects of material properties of HFDFRCC Using recycled fine aggregate on shear strength of RC beam

    Science.gov (United States)

    Shiratori, Yuhei; Watanabe, Ken

    2017-11-01

    In this study, we performed loading tests on RC beam specimens made of high-fluidity ductile-fiber-reinforced cementitious composites incorporating recycled fine aggregate with different water-binder ratios. We also performed nonlinear finite element analyses to investigate the effects of water-binder ratios and shear reinforcement bars on RC beam shear strength. Additionally, for some factors, we investigated the influence of the presence or absence of shear reinforcement bars on the shear strength of R-HFDFRCC RC beams. We found that fluctuations in the maximum load of the RC beam specimens attributable to differences in the water-binder ratio can generally be predicted if we understand the differences in the material properties (mainly compressive strength, tensile strength and ultimate tensile strain) of the tough, highly fluid cement compound materials incorporating recycled fine aggregate.

  17. Energy analysis of the ion beam from plasma focus

    International Nuclear Information System (INIS)

    Kilic, H.; Nardi, V.; Prior, W.

    1984-01-01

    The authors have experimentally determined the energy spectrum of a deuteron beam in the energy interval 100 KeV ≤ E ≤ 10 MeV, with typical beam current I ≥ 1-2 A. A 5 kJ (15 kV, 49 μF) plasma focus machine is used to generate the ion beam at relatively low pressure 3-4 Torr D/sub 2/ (beam anode) and at higher pressure 6-8 Torr D/sub 2/ (high-neutron-yield mode). The spectrum is obtained from two different methods, i.e. from ion time of flight - by using time delays of Faraday cup signals with respect to hard x-ray signals - and from ion filtering, (mylar filter with different thickness from 2.5 μm up to 500 μm are used to cover the Faraday cup). The Faraday cup is located in a differentially pumed chamber (10/sup -4/ - 10/sup -5/ Torr) which is separated from the plasma focus chamber (8-3 Torr) by a 150 μm diam. pinhole (12.5 μm thick tungsten foil). The pinhole and Faraday cup are positioned on the gun axis at a distance of 15 cm and 25 cm from the end of the anode respectively

  18. Focused ion beam patterned Hall nano-sensors

    International Nuclear Information System (INIS)

    Candini, A.; Gazzadi, G.C.; Di Bona, A.; Affronte, M.; Ercolani, D.; Biasiol, G.; Sorba, L.

    2007-01-01

    By means of focused ion beam milling, we fabricate Hall magnetometers with active areas as small as 100x100nm 2 . The constituent material can either be metallic (Au), semimetallic (Bi) or doped bulk semiconducting (Si doped GaAs). We experimentally show that Au nano-probes can work from room temperature down to liquid helium with magnetic flux sensitivity -1 Φ 0

  19. Direct deposition of gold on silicon with focused ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Nebiker, P.W.; Doebeli, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Muehle, R. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-09-01

    Irradiation with ions at very low energies (below 500 eV) no longer induces a removal of substrate material, but the ions are directly deposited on the surface. In this way, gold has been deposited on silicon with focused ion beam exposure and the properties of the film have been investigated with atomic force microscopy and Auger electron spectroscopy. (author) 3 figs., 1 ref.

  20. Performance predictions of a focused ion beam from a laser cooled and compressed atomic beam

    Energy Technology Data Exchange (ETDEWEB)

    Haaf, G. ten; Wouters, S. H. W.; Vredenbregt, E. J. D.; Mutsaers, P. H. A. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Geer, S. B. van der [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands)

    2014-12-28

    Focused ion beams are indispensable tools in the semiconductor industry because of their ability to image and modify structures at the nanometer length scale. Here, we report on performance predictions of a new type of focused ion beam based on photo-ionization of a laser cooled and compressed atomic beam. Particle tracing simulations are performed to investigate the effects of disorder-induced heating after ionization in a large electric field. They lead to a constraint on this electric field strength which is used as input for an analytical model which predicts the minimum attainable spot size as a function of, amongst others, the flux density of the atomic beam, the temperature of this beam, and the total current. At low currents (I < 10 pA), the spot size will be limited by a combination of spherical aberration and brightness, while at higher currents, this is a combination of chromatic aberration and brightness. It is expected that a nanometer size spot is possible at a current of 1 pA. The analytical model was verified with particle tracing simulations of a complete focused ion beam setup. A genetic algorithm was used to find the optimum acceleration electric field as a function of the current. At low currents, the result agrees well with the analytical model, while at higher currents, the spot sizes found are even lower due to effects that are not taken into account in the analytical model.

  1. Focusing of relativistic electron beams by a solid cone

    International Nuclear Information System (INIS)

    Chen, M; Sheng, Z M; Ma, Y Y; Li, Y T; Yuan, X H; Zhang, J

    2008-01-01

    A scheme for focusing relativistic electron beams has been proposed by use of a solid cone based upon two dimensional particle-in-cell simulations. We compare the transport of hot electrons, produced during the interaction of ultra-intense laser pulse with the targets, through the cone shape target and a flat target. It is found that relativistic electrons can be confined and focused effectively in the cone target case, where both the electron density and temperature have been increased more significantly than the flat target case

  2. Electron Beam Final Focus System For Thomson Scattering At Elbe

    CERN Document Server

    Krämer, J.M.; Bødkera, F.; Irman, A.; Jochmann, A.; Kristensena, J.P.; Lehnert, U.; Michel, P.; Schramm, U.; 10.1016/j.nima.2015.10.067

    2016-01-01

    The design of an electron beam final focus system (FFS) aiming for high-flux laser-Thomson backscattering X-ray sources at ELBE is presented. A telescope system consisting of four permanent magnet based quadrupoles was found to have significantly less chromatic aberrations than a quadrupole doublet or triplet as commonly used. Focusing properties like the position of the focal plane and the spot size are retained for electron beam energies between 20 and 30 MeV by adjusting the position of the quadrupoles individually on a motorized stage. The desired ultra-short electron bunches require an increased relative energy spread up to a few percent and, thus, second order chromatic effects must be taken into account. We also present the design and test results of the permanent magnet quadrupoles. Adjustable shunts allow for correction of the field strength and compensation of deviations in the permanent magnet material. For a beam emittance of 13 mm mrad, we predict focal spot sizes of about 40 μm (rms) and diverg...

  3. Electron beam final focus system for Thomson scattering at ELBE

    CERN Document Server

    Krämer, J.M.; Bødker, F.; Irman, A.; .Jochmann A.; Kristensen, J.P.; Lehnert U., HZDR; Michel, P.; Schrammb, U.; 10.1016/j.nima.2015.10.067

    2016-01-01

    The design of an electron beam final focus system (FFS) aiming for high-flux laser-Thomson backscattering X-ray sources at ELBE is presented. A telescope system consisting of four permanent magnet based quadrupoles was found to have significantly less chromatic aberrations than a quadrupole doublet or triplet as commonly used. Focusing properties like the position of the focal plane and the spot size are retained for electron beam energies between 20 and 30 MeV by adjusting the position of the quadrupoles individually on a motorized stage. The desired ultra-short electron bunches require an increased relative energy spread up to a few percent and, thus, second order chromatic effects must be taken into account. We also present the design and test results of the permanent magnet quadrupoles. Adjustable shunts allow for correction of the field strength and compensation of deviations in the permanent magnet material. For a beam emittance of 13 mm mrad, we predict focal spot sizes of about 40 μm (rms) and diverg...

  4. Induced focusing and conversion of a Gaussian beam into an elliptic ...

    Indian Academy of Sciences (India)

    Among several important findings, the finding that a very week probe beam can be guided and focused when power of both beams are well below their individual threshold for self-focusing, is a noteworthy one. It has been found that induced focusing is not possible for laser beams of any wavelength and beam radius.

  5. Focused-ion-beam deposition for 3-D nanostructure fabrication

    Science.gov (United States)

    Matsui, Shinji

    2007-04-01

    Three-dimensional nanostructure fabrication has been demonstrated by 30 keV Ga+ focused-ion-beam chemical-vapor-deposition (FIB-CVD) using a phenanthrene (C14H10) source as a precursor. Microstructure plastic arts is advocated as a new field using micro-beam technology, presenting one example of micro-wine-glass with 2.75 μm external diameter and 12 μm height. The deposition film is a diamond like amorphous carbon. A large Young's modulus that exceeds 600 GPa seems to present great possibilities for various applications. Producing of three-dimensional nanostructure is discussed. Micro-coil, nanoelectrostatic actuator and nano-space-wiring with 0.1 μm dimension are demonstrated as parts of nanomechanical system. Furthermore, filtering tool is also fabricated as a novel nano-tool for the manipulation and analysis of subcellular organelles.

  6. Transverse centroid oscillations in solenoidially focused beam transport lattices

    International Nuclear Information System (INIS)

    Lund, Steven M.; Wootton, Christopher J.; Lee, Edward P.

    2009-01-01

    Transverse centroid oscillations are analyzed for a beam in a solenoid transport lattice. Linear equations of motion are derived that describe small-amplitude centroid oscillations induced by displacement and rotational misalignments of the focusing solenoids in the transport lattice, dipole steering elements, and initial centroid offset errors. These equations are analyzed in a local rotating Larmor frame to derive complex-variable 'alignment functions' and 'bending functions' that efficiently describe the characteristics of the centroid oscillations induced by both mechanical misalignments of the solenoids and dipole steering elements. The alignment and bending functions depend only on the properties of the ideal lattice in the absence of errors and steering, and have associated expansion amplitudes set by the misalignments and steering fields, respectively. Applications of this formulation are presented for statistical analysis of centroid oscillations, calculation of actual lattice misalignments from centroid measurements, and optimal beam steering.

  7. Improving the intensity of a focused laser beam

    Science.gov (United States)

    Haddadi, Sofiane; Fromager, Michael; Louhibi, Djelloul; Hasnaoui, Abdelkrim; Harfouche, Ali; Cagniot, Emmanuel; ńit-Ameur, Kamel

    2015-03-01

    Let us consider the family of symmetrical Laguerre-Gaus modes of zero azimuthal order which will be denoted as LGp0 . The latter is made up of central lobe surrounded by p concentric rings of light. The fundamental mode LG00 is a Gaussian beam of width W. The focusing of a LGp0 beam of power P by a converging lens of focal length f produces a focal spot keeping the LGp0 -shape and having a central intensity I0= 2PW2/(λf)2 whatever the value of the radial order p. Many applications of lasers (laser marking, laser ablation, …) seek nowadays for a focal laser spot with the highest as possible intensity. For a given power P, increasing intensity I0 can be achieved by increasing W and reducing the focal length f. However, this way of doing is in fact limited because the ratio W/f cannot increase indefinitely at the risk of introducing a huge truncation upon the edge of the lens. In fact, it is possible to produce a single-lobed focal spot with a central intensity of about p times the intensity I0. This result has been obtained by reshaping (rectification) a LGp0 beam thanks to a proper Binary Diffractive Optical Element (BDOE). In addition, forcing a laser cavity to oscillate upon a LGp0 can improve the power extract due to a mode volume increasing with the mode order p. This could allow envisaging an economy of scale in term of laser pumping power for producing a given intensity I0. In addition, we have demonstrated that a rectified LGp0 beam better stand the lens spherical aberration than the usual Gaussian beam.

  8. Analytical possibilities of highly focused ion beams in biomedical field

    Science.gov (United States)

    Ren, M. Q.; Ji, X.; Vajandar, S. K.; Mi, Z. H.; Hoi, A.; Walczyk, T.; van Kan, J. A.; Bettiol, A. A.; Watt, F.; Osipowicz, T.

    2017-09-01

    At the Centre for Ion Beam Applications (CIBA), a 3.5 MV HVEE Singletron™ accelerator serves to provide MeV ion beams (mostly protons or He+) to six state-of-the-art beam lines, four of which are equipped with Oxford triplet magnetic quadrupole lens systems. This facility is used for a wide range of research projects, many of which are in the field of biomedicine. Here we presented a discussion of currently ongoing biomedical work carried out using two beamlines: The Nuclear Microscopy (NM) beamline is mainly used for trace elemental quantitative mapping using a combination of Particle Induced X-ray Emission (PIXE), to measure the trace elemental concentration of inorganic elements, Rutherford Backscattering Spectrometry (RBS), to characterise the organic matrix, and Scanning Transmission Ion Microscopy (STIM) to provide information on the lateral areal density variations of the specimen. Typically, a 2.1 MeV proton beam, focused to 1-2 μm spot size with a current of 100 pA is used. The high resolution single cell imaging beamline is equipped with direct STIM to image the interior structure of single cells with proton and alpha particles of sub-50 nm beam spot sizes. Simultaneously, forward scattering transmission ion microscopy (FSTIM) is utilized to generate images with improved contrast of nanoparticles with higher atomic numbers, such as gold nanoparticles, and fluorescent nanoparticles can be imaged using Proton Induced Fluorescence (PIF). Lastly, in this facility, RBS has been included as an option if required to determine the depth distribution of nanoparticles in cells, albeit with reduced spatial resolution.

  9. Optical fiber sensors fabricated by the focused ion beam technique

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Wang, Fei; Bang, Ole

    2012-01-01

    crystal fiber (PCF). Using this technique we fabricate a highly compact fiber-optic Fabry-Pérot (FP) refractive index sensor near the tip of fiber taper, and a highly sensitive in-line temperature sensor in PCF. We also demonstrate the potential of using FIB to selectively fill functional fluid......Focused ion beam (FIB) is a highly versatile technique which helps to enable next generation of lab-on-fiber sensor technologies. In this paper, we demonstrate the use application of FIB to precisely mill the fiber taper and end facet of both conventional single mode fiber (SMF) and photonic...

  10. Cryo-focused-ion-beam applications in structural biology.

    Science.gov (United States)

    Rigort, Alexander; Plitzko, Jürgen M

    2015-09-01

    The ability to precisely control the preparation of biological samples for investigations by electron cryo-microscopy is becoming increasingly important for ultrastructural imaging in biology. Precision machining instruments such as the focused ion beam microscope (FIB) were originally developed for applications in materials science. However, today we witness a growing use of these tools in the life sciences mainly due to their versatility, since they can be used both as manipulation and as imaging devices, when complemented with a scanning electron microscope (SEM). The advent of cryo-preparation equipment and accessories made it possible to pursue work on frozen-hydrated biological specimens with these two beam (FIB/SEM) instruments. In structural biology, the cryo-FIB can be used to site-specifically thin vitrified specimens for transmission electron microscopy (TEM) and tomography. Having control over the specimen thickness is a decisive factor for TEM imaging, as the thickness of the object under scrutiny determines the attainable resolution. Besides its use for TEM preparation, the FIB/SEM microscope can be additionally used to obtain three-dimensional volumetric data from biological specimens. The unique combination of an imaging and precision manipulation tool allows sequentially removing material with the ion beam and imaging the milled block faces by scanning with the electron beam, an approach known as FIB/SEM tomography. This review covers both fields of cryo-FIB applications: specimen preparation for TEM cryo-tomography and volume imaging by cryo-FIB/SEM tomography. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. The optics of the Final Focus Test Beam

    International Nuclear Information System (INIS)

    Irwin, J.; Brown, K.; Bulos, F.; Burke, D.; Helm, R.; Roy, G.; Ruth, R.; Yamamoto, N.; Oide, K.

    1991-01-01

    The Final Focus Test Beam (FFTB), currently under construction at the end of the SLAC Linac, is being built by an international collaboration as a test bed for ideas and methods required in the design and construction of final focus systems for next generation e + e - linear colliders. The FFTB lattice shown is based on the previously developed principle of using sextupole pairs in a dispersive region to compensate chromaticity. The linear lattice was optimized for length, and implementation of diagnostic procedures. The transformations between sextupole pairs (CCX and CCY) are exactly -I, the matrix for the intermediate transformer (BX) is exactly diagonal, and the dispersion function has zero slope at the sextupoles and is thus zero at the minimum of the β x function in the intermediate transformer

  12. Evaluation of pulsed ion beam produced in plasmas focus device

    International Nuclear Information System (INIS)

    Kishimoto, R.; Ito, H.; Masugata, K.

    2013-01-01

    The characteristics of ion beams produced in a Mather-type plasma focus device have been studied. When a capacitor bank of 41.6 μF was charged to 30 kV, the discharge current reached a peak current of 450 kA, and after the current dip, an ion current density of 8 kA/cm 2 with a pulse width of 60 ns was obtained 110 mm downstream from the top of the anode on the axis. Ion beam was found to be emitted with very large spread of emission angle up to ±80deg. To evaluate the dependence of ion energy spectrum on the emission angle, we arrayed the incident angle resolved energy spectrometers simultaneously at different angular positions on a circumference of 110 mm in radius, centered at the focus. From the evaluation, we found that the ion energy was distributed from 0.1 MeV to 2 MeV and that ions with small emission angle have higher energy and wide spread of incidence angle. In addition, the ion energy and spread of incidence angle decrease with increasing emission angle. (author)

  13. Measuring micron size beams in the SLC final focus

    International Nuclear Information System (INIS)

    McCormick, D.; Ross, M.; DeBarger, S.

    1994-10-01

    A pair of high resolution wire scanners have been built and installed in the SLC final focus. The final focus optics uses a set of de-magnifying telescopes, and an ideal location for a beam size monitor is at one of the magnified image points of the interaction point. The image point chosen for these scanners is in the middle of a large bend magnet. The design beam spots here are about 2 microns in the vertical and 20 microns in the horizontal plane. The scanners presented a number of design challenges. In this paper we discuss the mechanical design of the scanner, and fabrication techniques of its ceramic wire support card which holds many 4 and 7 um carbon wires. Accurate motion of the wire during a scan is critical. In this paper we describe tests of stepper motors, gear combinations, and radiation hardened encoders needed to produce the required motion with a step resolution of 80 nanometers. Also presented here are the results of scattered radiation detector placement studies carried out to optimize the signal from the 4 micron wires. Finally, we present measurements from the scanner

  14. Pin cushion plasmonic device for polarization beam splitting, focusing, and beam position estimation.

    Science.gov (United States)

    Lerman, Gilad M; Levy, Uriel

    2013-03-13

    Great hopes rest on surface plasmon polaritons' (SPPs) potential to bring new functionalities and applications into various branches of optics. In this paper, we demonstrate a pin cushion structure capable of coupling light from free space into SPPs, split them based on the polarization content of the illuminating beam of light, and focus them into small spots. We also show that for a circularly or randomly polarized light, four focal spots will be generated at the center of each quarter circle comprising the pin cushion device. Furthermore, following the relation between the relative intensity of the obtained four focal spots and the relative position of the illuminating beam with respect to the structure, we propose and demonstrate the potential use of our structure as a miniaturized plasmonic version of the well-known four quadrant detector. Additional potential applications may vary from multichannel microscopy and multioptical traps to real time beam tracking systems.

  15. Production and focusing of high-currents beams of relativistic electrons up to high densities

    International Nuclear Information System (INIS)

    Gordeev, A.V.; Korolev, V.D.; Sidorov, Y.L.; Smirnov, V.P.

    1975-01-01

    The results of beam focusing experiments carried out on the ''MS'' and ''Triton'' accelerators are presented. The magnetic insulation of vacuum lines is described. Some experiments on beam focusing in the diode gap with a plasma filling are discussed. (MOW)

  16. Focused ion beam lithography for rapid prototyping of metallic films

    Energy Technology Data Exchange (ETDEWEB)

    Osswald, Patrick; Kiermaier, Josef; Becherer, Markus; Schmitt-Landsiedel, Doris [Lehrstuhl fuer Technische Elektronik, TU Muenchen, Munich (Germany)

    2010-07-01

    We present FIB-lithography methods for rapid and cost-effective prototyping of metal structures covering the deep-submicron- to the millimeter-range in a single lithography cycle. Focused ion beam (FIB) systems are widely used in semiconductor industry and research facilities for both analytical testing and prototyping. A typical application is to apply electrical contact to micron-sized sensors/particles by FIB induced metal deposition. However, as for E-beam lithography, patterning times for large area bonding pads are unacceptably long, resulting in cost-intensive prototyping. In this work, we optimized FIB lithography processing for negative and positive imaging mode to form metallic structures for large-areas down do the sub-100 nm range. For negative lithography features are defined by implanting Ga{sup +}-ions into a commercial photo resist, without affecting the underlying structures by impinging ions. The structures are highly suitable for following lift-off processing due to the undercut of the resist.Metallic feature size of down to 150 nm are achievable. For positive lithography a PMMA resist is exposed in FIB irradiation. Due to the very low dose (3.10{sup 12} ions/cm{sup 2}) the writing time for an e.g. 100 {mu}m x 100 {mu}m square is approx. 15 seconds. The developed resist is used for subsequent wet chemical etching, obtaining a 100 nm resolution in metal layers.

  17. The optics of the Final Focus Test Beam

    International Nuclear Information System (INIS)

    Irwin, J.; Brown, K.; Bulos, F.; Burke, D.; Helm, R.; Roy, G.; Ruth, R.; Yamamoto, N.; Oide, K.

    1991-05-01

    The Final Focus Test Beam (FFTB), currently under construction at the end of the SLAC Linac, is being built by an international collaboration as a test bed for ideas and methods required in the design and construction of final focus systems for next generation e + e - linear colliders. The FFTB lattice is based on the previously developed principle of using sextupole pairs in a dispersive region to compensate chromaticity. The linear lattice was optimized for length, and implementation of diagnostic procedures. The transformations between sextupole pairs (CCX and CCY) are exactly -I, the matrix for the intermediate transformer (BX) is exactly diagonal, and the dispersion function has zero slope at the sextupoles and is thus zero at the minimum of the β x function in the intermediate transformer. The introduction of sextupoles in final focus systems leads to the presence of additional optical aberrations, and synchrotron radiation in the dipoles also enlarges the final spot size. The important fourth-order optical aberrations which determine the main features of the design have been identified. Additional lower order aberrations arise in the implementation of these designs, since the real system is not the ideal design. We concentrate on these aberrations and describe strategies for their diagnosis and correction

  18. Introduction to focused ion beams instrumentation, theory, techniques and practice

    CERN Document Server

    Giannuzzi, Lucille A

    2005-01-01

    The focused ion beam (FIB) instrument has experienced an intensive period of maturation since its inception. Numerous new techniques and applications have been brought to fruition, and over the past few years, the FIB has gained acceptance as more than just an expensive sample preparation tool. It has taken its place among the suite of other instruments commonly available in analytical and forensic laboratories, universities, geological, medical and biological research institutions, and manufacturing plants. Although the utility of the FIB is not limited to the preparation of specimens for subsequent analysis by other analytical techniques, it has revolutionized the area of TEM specimen preparation. The FIB has also been used to prepare samples for numerous other analytical techniques, and offers a wide range of other capabilities. While the mainstream of FIB usage remains within the semiconductor industry, FIB usage has expanded to applications in metallurgy, ceramics, composites, polymers, geology, art, bio...

  19. Chemically Induced Phase Transformation in Austenite by Focused Ion Beam

    Science.gov (United States)

    Basa, Adina; Thaulow, Christian; Barnoush, Afrooz

    2014-03-01

    A highly stable austenite phase in a super duplex stainless steel was subjected to a combination of different gallium ion doses at different acceleration voltages. It was shown that contrary to what is expected, an austenite to ferrite phase transformation occurred within the focused ion beam (FIB) milled regions. Chemical analysis of the FIB milled region proved that the gallium implantation preceded the FIB milling. High resolution electron backscatter diffraction analysis also showed that the phase transformation was not followed by the typical shear and plastic deformation expected from the martensitic transformation. On the basis of these observations, it was concluded that the change in the chemical composition of the austenite and the local increase in gallium, which is a ferrite stabilizer, results in the local selective transformation of austenite to ferrite.

  20. Theoretical study on second-harmonic generation of focused vortex beams

    Science.gov (United States)

    Tang, Daolong; Wang, Jing; Ma, Jingui; Zhou, Bingjie; Yuan, Peng; Xie, Guoqiang; Zhu, Heyuan; Qian, Liejia

    2018-03-01

    Second-harmonic generation (SHG) provides a promising route for generating vortex beams of both short wavelength and large topological charge. Here we theoretically investigate the efficiency optimization and beam characteristics of focused vortex-beam SHG. Owing to the increasing beam divergence, vortex beams have distinct features in SHG optimization compared with a Gaussian beam. We show that, under the noncritical phase-matching condition, the Boyd and Kleinman prediction of the optimal focusing parameter for Gaussian-beam SHG remains valid for vortex-beam SHG. However, under the critical phase-matching condition, which is sensitive to the beam divergence, the Boyd and Kleinman prediction is no longer valid. In contrast, the optimal focusing parameter for maximizing the SHG efficiency strongly depends on the vortex order. We also investigate the effects of focusing and phase-matching conditions on the second-harmonic beam characteristics.

  1. Solenoidal Fields for Ion Beam Transport and Focusing

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Edward P.; Leitner, Matthaeus

    2007-11-01

    In this report we calculate time-independent fields of solenoidal magnets that are suitable for ion beam transport and focusing. There are many excellent Electricity and Magnetism textbooks that present the formalism for magnetic field calculations and apply it to simple geometries [1-1], but they do not include enough relevant detail to be used for designing a charged particle transport system. This requires accurate estimates of fringe field aberrations, misaligned and tilted fields, peak fields in wire coils and iron, external fields, and more. Specialized books on magnet design, technology, and numerical computations [1-2] provide such information, and some of that is presented here. The AIP Conference Proceedings of the US Particle Accelerator Schools [1-3] contain extensive discussions of design and technology of magnets for ion beams - except for solenoids. This lack may be due to the fact that solenoids have been used primarily to transport and focus particles of relatively low momenta, e.g. electrons of less than 50 MeV and protons or H- of less than 1.0 MeV, although this situation may be changing with the commercial availability of superconducting solenoids with up to 20T bore field [1-4]. Internal reports from federal laboratories and industry treat solenoid design in detail for specific applications. The present report is intended to be a resource for the design of ion beam drivers for Inertial Fusion Energy [1-5] and Warm Dense Matter experiments [1-6], although it should also be useful for a broader range of applications. The field produced by specified currents and material magnetization can always be evaluated by solving Maxwell's equations numerically, but it is also desirable to have reasonably accurate, simple formulas for conceptual system design and fast-running beam dynamics codes, as well as for general understanding. Most of this report is devoted to such formulas, but an introduction to the Tosca{copyright} code [1-7] and some

  2. Focused ion beam structuring of low melting polymeric materials

    International Nuclear Information System (INIS)

    Schmied, R.

    2014-01-01

    This thesis focuses on heating effects during focused ion beam (FIB) processing of low melting polymers. The combined approach using experiments and simulations identifies the in part massive local temperatures as a convolution between intrinsic ion-matter effects and a considerable, technically-induced heating component. While the former is invariable, the latter has been minimized by an alternative process strategy which massively improves the morphological stability and minimizes chemical damage during FIB processing, thus opening new possibilities for application on sensitive, low melting materials. The study starts with systematic experimental investigations which strongly suggested the existence of a technically-induced heating component as a consequence of classically-used serpentine or raster-like patterning strategies. Based on these results, a combined simulation approach of ion trajectories and thermal spike model calculations have been employed to get a deeper insight into spatial and temporal temperature evolution. The results were then combined with the thermodynamic behavior of polymers by means of melting and volatizing temperatures. The comparison of these simulationbased predictions with real FIB experiments revealed very good agreement, proving the applicability of the approach used to describe the temperature evolution from a fundamental point of view. As a next step, these simulations were then applied to the dierent scanning strategies which further con rmed the existence of a technically-induced heating component via classically-used patterning approaches. Due to the deep insight gained via simulations, an alternative patterning strategy was developed, which was expected to minimize these avoidable influences. This new strategy was then evaluated using a multi-technique approach, which revealed strongly reduced chemical damage together with increasing morphological stabilities even for temperature-sensitive polymers. Finally, this alternative

  3. Editorial: Focus on Laser- and Beam-Driven Plasma Accelerators

    Science.gov (United States)

    Joshi, Chan; Malka, Victor

    2010-04-01

    The ability of short but intense laser pulses to generate high-energy electrons and ions from gaseous and solid targets has been well known since the early days of the laser fusion program. However, during the past decade there has been an explosion of experimental and theoretical activity in this area of laser-matter interaction, driven by the prospect of realizing table-top plasma accelerators for research, medical and industrial uses, and also relatively small and inexpensive plasma accelerators for high-energy physics at the frontier of particle physics. In this focus issue on laser- and beam-driven plasma accelerators, the latest advances in this field are described. Focus on Laser- and Beam-Driven Plasma Accelerators Contents Slow wave plasma structures for direct electron acceleration B D Layer, J P Palastro, A G York, T M Antonsen and H M Milchberg Cold injection for electron wakefield acceleration X Davoine, A Beck, A Lifschitz, V Malka and E Lefebvre Enhanced proton flux in the MeV range by defocused laser irradiation J S Green, D C Carroll, C Brenner, B Dromey, P S Foster, S Kar, Y T Li, K Markey, P McKenna, D Neely, A P L Robinson, M J V Streeter, M Tolley, C-G Wahlström, M H Xu and M Zepf Dose-dependent biological damage of tumour cells by laser-accelerated proton beams S D Kraft, C Richter, K Zeil, M Baumann, E Beyreuther, S Bock, M Bussmann, T E Cowan, Y Dammene, W Enghardt, U Helbig, L Karsch, T Kluge, L Laschinsky, E Lessmann, J Metzkes, D Naumburger, R Sauerbrey, M. Scḧrer, M Sobiella, J Woithe, U Schramm and J Pawelke The optimum plasma density for plasma wakefield excitation in the blowout regime W Lu, W An, M Zhou, C Joshi, C Huang and W B Mori Plasma wakefield acceleration experiments at FACET M J Hogan, T O Raubenheimer, A Seryi, P Muggli, T Katsouleas, C Huang, W Lu, W An, K A Marsh, W B Mori, C E Clayton and C Joshi Electron trapping and acceleration on a downward density ramp: a two-stage approach R M G M Trines, R Bingham, Z Najmudin

  4. Focused beam reflectance measurement to monitor nimodipine precipitation process.

    Science.gov (United States)

    Xu, Xiaoming; Siddiqui, Akhtar; Khan, Mansoor A

    2013-11-18

    Crystallization of nimodipine in liquid-filled soft gelatin capsule during storage was reported for some commercial products, resulting in product recalls due to product quality and more importantly safety concerns. In this study, a real time particle monitoring tool, focused beam reflectance measurement, was used to evaluate the precipitation conditions of nimodipine in co-solvents. Upon water addition, two particle populations were discovered, appearing at different percentage of water content. Two transitions (i.e. sudden increase in particle counts) were observed, possibility related to nucleation and crystal growth of nimodipine. Furthermore, lowering storage temperature increased the tendency of nimodipine precipitation. Most critically, it was determined that with certain excipient, the drug precipitation occurred at approximately 7% (w/w) water content. Considering that all the orally administered liquid filled soft gelatin capsule shells contain residue water content as plasticizer, moisture transfer from the shell to the formulation may occur during long term storage, resulting in drug precipitation, particularly under cold temperature conditions. Published by Elsevier B.V.

  5. Dwell time adjustment for focused ion beam machining

    International Nuclear Information System (INIS)

    Taniguchi, Jun; Satake, Shin-ichi; Oosumi, Takaki; Fukushige, Akihisa; Kogo, Yasuo

    2013-01-01

    Focused ion beam (FIB) machining is potentially useful for micro/nano fabrication of hard brittle materials, because the removal method involves physical sputtering. Usually, micro/nano scale patterning of hard brittle materials is very difficult to achieve by mechanical polishing or dry etching. Furthermore, in most reported examples, FIB machining has been applied to silicon substrates in a limited range of shapes. Therefore, a versatile method for FIB machining is required. We previously established the dwell time adjustment for mechanical polishing. The dwell time adjustment is calculated by using a convolution model derived from Preston’s hypothesis. More specifically, the target removal shape is a convolution of the unit removal shape, and the dwell time is calculated by means of one of four algorithms. We investigate these algorithms for dwell time adjustment in FIB machining, and we found that a combination a fast Fourier transform calculation technique and a constraint-type calculation is suitable. By applying this algorithm, we succeeded in machining a spherical lens shape with a diameter of 2.93 μm and a depth of 203 nm in a glassy carbon substrate by means of FIB with dwell time adjustment

  6. Beam-based alignment and tuning procedures for e+e- collider final focus systems

    International Nuclear Information System (INIS)

    Bulos, F.; Burke, D.; Helm, R.; Irwin, J.; Odian, A.; Roy, G.; Ruth, R.; Yamamoto

    1991-01-01

    For future linear colliders, with very small emittances and beam sizes and demanding tolerances on final focus system alignment and magnet errors, it becomes increasingly important to use the beam as a diagnostic tool. The authors report here procedures they have identified and will be implemented in the Final Focus Test Beam at SLAC incorporating (1) quadrupole strength changes, (2) central orbit modifications, (3) spot size measurements, and (4) beam stability monitoring

  7. Beam-based alignment and tuning procedures for e+e- collider final focus systems

    International Nuclear Information System (INIS)

    Bulos, F.; Burke, D.; Helm, R.; Irwin, J.; Odian, A.; Roy, G.; Ruth, R.; Yamamoto, N.

    1991-05-01

    For future linear colliders, with very small emittances and beam sizes and demanding tolerances on final focus system alignment and magnet errors, it becomes increasingly important to use the beam as a diagnostic tool. We report here procedures we have identified and will be implemented in the Final Focus Test Beam at SLAC incorporating (1) quadrupole strength changes, (2) central orbit modifications, (3) spot size measurements, and (4) beam stability monitoring. 3 refs., 4 figs., 3 tabs

  8. Editorial: Focus on X-ray Beams with High Coherence

    Science.gov (United States)

    Robinson, Ian; Gruebel, Gerhard; Mochrie, Simon

    2010-03-01

    This editorial serves as the preface to a special issue of New Journal of Physics, which collects together solicited papers on a common subject, x-ray beams with high coherence. We summarize the issue's content, and explain why there is so much current interest both in the sources themselves and in the applications to the study of the structure of matter and its fluctuations (both spontaneous and driven). As this collection demonstrates, the field brings together accelerator physics in the design of new sources, particle physics in the design of detectors, and chemical and materials scientists who make use of the coherent beams produced. Focus on X-ray Beams with High Coherence Contents Femtosecond pulse x-ray imaging with a large field of view B Pfau, C M Günther, S Schaffert, R Mitzner, B Siemer, S Roling, H Zacharias, O Kutz, I Rudolph, R Treusch and S Eisebitt The FERMI@Elettra free-electron-laser source for coherent x-ray physics: photon properties, beam transport system and applications E Allaria, C Callegari, D Cocco, W M Fawley, M Kiskinova, C Masciovecchio and F Parmigiani Beyond simple exponential correlation functions and equilibrium dynamics in x-ray photon correlation spectroscopy Anders Madsen, Robert L Leheny, Hongyu Guo, Michael Sprung and Orsolya Czakkel The Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS) Sébastien Boutet and Garth J Williams Dynamics and rheology under continuous shear flow studied by x-ray photon correlation spectroscopy Andrei Fluerasu, Pawel Kwasniewski, Chiara Caronna, Fanny Destremaut, Jean-Baptiste Salmon and Anders Madsen Exploration of crystal strains using coherent x-ray diffraction Wonsuk Cha, Sanghoon Song, Nak Cheon Jeong, Ross Harder, Kyung Byung Yoon, Ian K Robinson and Hyunjung Kim Coherence properties of the European XFEL G Geloni, E Saldin, L Samoylova, E Schneidmiller, H Sinn, Th Tschentscher and M Yurkov Fresnel coherent diffractive imaging: treatment and analysis of data G J

  9. Literature in focus: Particle beams from theory to practice

    CERN Multimedia

    2003-01-01

    Wednesday 1st October 16 h00 - Central Library CERN's Frank Zimmermann and DESY's Michiko G. Minty had their book 'Measurement and control of charged particle beams' published a few months ago by Springer. Frank Zimmermann, a young but already well established accelerator physicist, was awarded the European Accelerator Prize by the Interdivisional Group on Accelerators of the European Physical Society last year. Mr. Zimmermann was particularly cited for his significant contribution to the understanding of fast ion and electron cloud instabilities. The book is the first comprehensive and systematic review of all methods used for the measurement, correction, and control of the beam dynamics of modern particle accelerators and is intended for graduate students starting research or work in the field of beam physics. Specific techniques and methods for relativistic beams are illustrated by examples from operational accelerators, like CERN, DESY, SLAC, KEK, LBNL, and FNAL. Problems and solutions enhance the book...

  10. Performance verification of focus variation and confocal microscopes measuring tilted ultra-fine surfaces

    DEFF Research Database (Denmark)

    Quagliotti, Danilo; Baruffi, Federico; Tosello, Guido

    2016-01-01

    The behaviour of two optical instruments, scilicet a laser scanning confocal microscope and a focus-variation microscope, was investigated considering measurements of tilted surfaces. The measured samples were twelve steel artefacts for mould surface finish reference, covering Sa roughness...... parameter in the range (101—103) nm. The 3D surface texture parameters considered were Sa, Sq and Sdq. The small working distance of the confocal microscope objectives influenced the measurement setup, preventing from selecting a high tilting angle. The investigation was carried out comparing measurements...... of flat surfaces (0° tilt) with measurements of 12.5° tilted surfaces. The confocal microscope results showed a high sensitivity to tilting due to the laser beam reflection on the metal surfaces. The focus variation microscope results were more robust with respect to the considered angular variation...

  11. Induced focusing and conversion of a Gaussian beam into an elliptic ...

    Indian Academy of Sciences (India)

    We have presented an investigation of the induced focusing in Kerr media of two laser beams, the pump beam and ... in nonlinear media has been confined to cylindrical Gaussian beams. In a few re- cent publications .... Inserting suitable chosen trial functions in the variational principle, we can obtain a reduced variational ...

  12. Focusing of submicron beams for TeV-scale e+e- linear colliders

    International Nuclear Information System (INIS)

    Balakin, V.; Alexandrov, V.A.; Mikhailichenko, A.; Floettmann, K.; Peters, F.; Voss, G.; Bharadwaj, V.; Halling, M.; Holt, J.A.; Buon, J.; Jeanjean, J.; LeDiberder, F.; Lepeltier, V.; Puzo, P.; Heimlinger, G.; Settles, R.; Stierlin, U.; Hayano, H.; Ishihara, N.; Nakayama, H.; Oide, K.; Shintake, T.; Takeuchi, Y.; Yamamoto, N.; Bulos, F.; Burke, D.; Field, R.; Hartman, S.; Helm, R.; Irwin, J.; Iverson, R.; Rokni, S.; Roy, G.; Spence, W.; Tenenbaum, P.; Wagner, S.R.; Walz, D.; Williams, S.

    1995-01-01

    First experimental results from the final focus test beam (FFTB) are reported. The vertical dimension of a 47-GeV electron beam from the SLAC linac has been reduced at the focal point of the FFTB by a demagnification of 320 to a beam height of approximately 70 nm

  13. Demonstrating H- beam focusing using an elliptical einzel lens

    Science.gov (United States)

    Lawrie, S. R.; Faircloth, D. C.; Letchford, A. P.; Whitehead, M. O.; Wood, T.

    2017-08-01

    H- ion source research is being performed at the ISIS spallation neutron and muon facility on a dedicated Vessel for Extraction and Source Plasma Analyses (VESPA). The ion extraction and optics system presently being used on ISIS is centered on a combined-function sector dipole magnet. This traps cesium vapor escaping the ion source; mass-separates co-extracted electrons and stripped neutrals, and weak-focusses the highly asymmetric slit-shaped ion beam. Unfortunately the added drift length through the magnet under strong space-charge forces means up to 50% of the beam is collimated on the magnet. The VESPA has shown that the ISIS ion source actually produces 80 mA of beam current at standard settings, but because of magnet collimation only 55 mA is injected into the solenoid Low Energy Beam Transport (LEBT). A new purely electrostatic post-extraction system incorporating an einzel lens with an elliptical aperture is currently under test. This allows much greater flexibility of perveance and phase space matching for injection into the LEBT and Radio Frequency Quadrupole (RFQ). This paper discusses high voltage breakdown mitigation strategies and presents the first results of the novel elliptical transport system. So far, 70 mA of beam has been transported through the new system with a normalized transverse RMS emittance of 0.2 π mm mrad.

  14. Kinetic equilibrium of space charge dominated beams in a misaligned quadrupole focusing channel

    International Nuclear Information System (INIS)

    Goswami, A.; Sing Babu, P.; Pandit, V. S.

    2013-01-01

    The dynamics of intense beam propagation through the misaligned quadrupole focusing channel has been studied in a self-consistent manner using nonlinear Vlasov-Maxwell equations. The equations of motion of the beam centroid have been developed and found to be independent of any specific beam distribution. A Vlasov equilibrium distribution and beam envelope equations have been obtained, which provide us a theoretical tool to investigate the dynamics of intense beam propagating in a misaligned quadrupole focusing channel. It is shown that the displaced quadrupoles only cause the centroid of the beam to wander off axis. The beam envelope around the centroid obeys the familiar Kapchinskij-Vladimirskij envelope equation that is independent of the centroid motion. However, the rotation of the quadrupole about its optical axis affects the beam envelope and causes an increase in the projected emittances in the two transverse planes due to the inter-plane coupling

  15. Micro-patterns fabrication using focused proton beam lithography

    Czech Academy of Sciences Publication Activity Database

    Cutroneo, Mariapompea; Havránek, Vladimír; Macková, Anna; Semián, Vladimír; Torrisi, L.; Calcagno, L.

    2016-01-01

    Roč. 371, MAR (2016), s. 344-349 ISSN 0168-583X. [22nd International conference on Ion Beam Analysis (IBA). Opatija, 14.06.2015-19.06.2015] R&D Projects: GA MŠk(CZ) LM2011019; GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:61389005 Keywords : ion-micro-beam * STIM analysis * pattern in PMMA Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.109, year: 2016

  16. Equilibrium and stability of off-axis periodically focused particle beams

    International Nuclear Information System (INIS)

    Moraes, J.S.; Pakter, R.; Rizzato, F.B.

    2004-01-01

    A general equation for the centroid motion of free, continuous, intense beams propagating off axis in solenoidal periodic focusing fields is derived. The centroid equation is found to be independent of the specific beam distribution and may exhibit unstable solutions. A new Vlasov equilibrium for off-axis beam propagation is also obtained. The properties of the equilibrium and the relevance of centroid motion to beam confinement are discussed

  17. Fabrication of nano structures in thin membranes with focused ion beam technology

    NARCIS (Netherlands)

    Gadgil, V.J.; Tong, D.H.; Cesa, Y.; Bennink, Martin L.

    2009-01-01

    In recent years, Focused Ion Beam (FIB) technology has emerged as an important tool for nanotechnology [V.J. Gadgil, F. Morrissey, Encyclopaedia of Nanoscience and Nanotechnology, vol. 1, American Science Publishers, ISBN: 1-58883-057-8, 2004, p101.]. In this paper, applications of focused ion beam

  18. Fridge: Focused fine-tuning of ridge regression for personalized predictions.

    Science.gov (United States)

    Hellton, Kristoffer H; Hjort, Nils Lid

    2018-04-15

    Statistical prediction methods typically require some form of fine-tuning of tuning parameter(s), with K-fold cross-validation as the canonical procedure. For ridge regression, there exist numerous procedures, but common for all, including cross-validation, is that one single parameter is chosen for all future predictions. We propose instead to calculate a unique tuning parameter for each individual for which we wish to predict an outcome. This generates an individualized prediction by focusing on the vector of covariates of a specific individual. The focused ridge-fridge-procedure is introduced with a 2-part contribution: First we define an oracle tuning parameter minimizing the mean squared prediction error of a specific covariate vector, and then we propose to estimate this tuning parameter by using plug-in estimates of the regression coefficients and error variance parameter. The procedure is extended to logistic ridge regression by using parametric bootstrap. For high-dimensional data, we propose to use ridge regression with cross-validation as the plug-in estimate, and simulations show that fridge gives smaller average prediction error than ridge with cross-validation for both simulated and real data. We illustrate the new concept for both linear and logistic regression models in 2 applications of personalized medicine: predicting individual risk and treatment response based on gene expression data. The method is implemented in the R package fridge. Copyright © 2018 John Wiley & Sons, Ltd.

  19. Drift compression and final focus for intense heavy ion beams with nonperiodic, time-dependent lattice

    Directory of Open Access Journals (Sweden)

    Hong Qin

    2004-10-01

    Full Text Available In the currently envisioned configurations for heavy ion fusion, it is necessary to longitudinally compress the beam bunches by a large factor after the acceleration phase. Because the space-charge force increases as the beam is compressed, the beam size in the transverse direction will increase in a periodic quadrupole lattice. If an active control of the beam size is desired, a larger focusing force is needed to confine the beam in the transverse direction, and a nonperiodic quadrupole lattice along the beam path is necessary. In this paper, we describe the design of such a focusing lattice using the transverse envelope equations. A drift compression and final focus lattice should focus the entire beam pulse onto the same focal spot on the target. This is difficult with a fixed lattice, because different slices of the beam may have different perveance and emittance. Four time-dependent magnets are introduced in the upstream of drift compression to focus the entire pulse onto the same focal spot. Drift compression and final focusing schemes are developed for a typical heavy ion fusion driver and for the integrated beam experiment being designed by the Heavy Ion Fusion Virtual National Laboratory.

  20. The Next Generation Focusing Lenses for Proton Beam Writing

    Science.gov (United States)

    2009-07-28

    Microbeams . The target chamber is under construction and the system is expected to be assembled in October 2009. The PI has shown initial test on PBW for Ni...conducted 13 guest lectures and conference seminars on proton beam writing. At all these seminars work was presented that was partially supported by...Frontiers of Nano-Science & Nano-technology, Nanocore& NUSNNI, NUS, Singapore. 5 Invited Oral presentation: 2008 June at the 25th Conference of

  1. Space lattice focusing on the way to extremely low accelerated beam divergence

    CERN Document Server

    Kushin, V V

    1999-01-01

    It is widely known the multiple channel acceleration is the most adequate way to save initial beam parameters due to the possibility of decreasing Coulomb forces in intensive input beams. To keep beam initial emittance and divergence for high enough specific value of the injection ion beam during acceleration the input beam should be split on multiple beams and every the micro beam must be screened from each other as much as possible. On the other hand, it is very much desirable to keep the total macro beam rather compact transversally and try to accelerate all the micro beams within the same accelerator structure at the same RF field. Attempts to use conventional quadruple focusing channels both RF and electrostatic for multiple beam acceleration usually lead to extremely complicate and bulky construction of the structure. We suppose multiple beam linac channels with alternating phase focusing (APF) as more adequate for the purpose while they are limited by less values of beam capture into acceleration proce...

  2. Multi-slit triode ion optical system with ballistic beam focusing

    Energy Technology Data Exchange (ETDEWEB)

    Davydenko, V., E-mail: V.I.Davydenko@inp.nsk.su; Amirov, V.; Gorbovsky, A.; Deichuli, P.; Ivanov, A.; Kolmogorov, A.; Kapitonov, V.; Mishagin, V.; Shikhovtsev, I.; Sorokin, A.; Stupishin, N. [Budker Institute of Nuclear Physics, Novosibirsk 630090 (Russian Federation); Karpushov, A. N. [Ecole Polytechnique Fédérale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland); Smirnov, A. [Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States); Uhlemann, R. [Institute of Energy and Climate Research-Plasma Physics, Research Center Juelich, 52425 Juelich (Germany)

    2016-02-15

    Multi-slit triode ion-optical systems with spherical electrodes are of interest for formation of intense focused neutral beams for plasma heating. At present, two versions of focusing multi-slit triode ion optical system are developed. The first ion optical system forms the proton beam with 15 keV energy, 140 A current, and 30 ms duration. The second ion optical system is intended for heating neutral beam injector of Tokamak Configuration Variable (TCV). The injector produces focused deuterium neutral beam with 35 keV energy, 1 MW power, and 2 s duration. In the later case, the angular beam divergence of the neutral beam is 20-22 mrad in the direction across the slits of the ion optical system and 12 mrad in the direction along the slits.

  3. Designing Neutralized Drift Compression for Focusing of Intense Ion Beam Pulses in a Background Plasma

    International Nuclear Information System (INIS)

    Kaganovich, I.D.; Davidson, R.C.; Dorf, M.; Startsev, E.A.; Barnard, J.J.; Friedman, A.; Lee, E.P.; Lidia, S.M.; Logan, B.G.; Roy, P.K.; Seidl, P.A.; Welch, D.R.; Sefkow, A.B.

    2009-01-01

    Neutralized drift compression offers an effective method for particle beam focusing and current amplification. In neutralized drift compression, a linear radial and longitudinal velocity drift is applied to a beam pulse, so that the beam pulse compresses as it drifts in the drift-compression section. The beam intensity can increase more than a factor of 100 in both the radial and longitudinal directions, resulting in more than 10,000 times increase in the beam number density during this process. The self-electric and self-magnetic fields can prevent tight ballistic focusing and have to be neutralized by supplying neutralizing electrons. This paper presents a survey of the present theoretical understanding of the drift compression process and plasma neutralization of intense particle beams. The optimal configuration of focusing and neutralizing elements is discussed in this paper.

  4. Active echolocation beam focusing in the false killer whale, Pseudorca crassidens.

    Science.gov (United States)

    Kloepper, Laura N; Nachtigall, Paul E; Donahue, Megan J; Breese, Marlee

    2012-04-15

    The odontocete sound production system is highly complex and produces intense, directional signals that are thought to be focused by the melon and the air sacs. Because odontocete echolocation signals are variable and the emitted click frequency greatly affects the echolocation beam shape, investigations of beam focusing must account for frequency-related beam changes. In this study we tested whether the echolocation beam of a false killer whale changed depending on target difficulty and distance while also accounting for frequency-related changes in the echolocation beam. The data indicate that the false killer whale changes its beam size according to target distance and difficulty, which may be a strategy of maximizing the energy of the target echo. We propose that the animal is using a strategy of changing the focal region according to target distance and that this strategy is under active control.

  5. Transverse characterization of focused Bessel beams with angular momentum applied to study degree of coherence

    International Nuclear Information System (INIS)

    He, Xi; Wu, Fengtie; Chen, Ziyang; Pu, Jixiong; Chavez-Cerda, Sabino

    2016-01-01

    The transverse focusing properties at the ‘pseudo-focal’ plane of coherent Bessel beams with angular momentum are analyzed in detail. The transverse magnification of the central dark region of Bessel beams at this pseudo-focal plane is derived for the first time by calculating the ratio of the magnitude of the transverse components of the corresponding wave vectors before and after the focusing lens. We test our results experimentally with coherent laser Bessel beams and excellent agreement is observed. Then, an LED light source is used to generate Bessel beams. By modifying the coherence of the LED light source, we observe that by reducing coherence a smaller and shallower central dark region of Bessel beams with angular momentum is produced at the pseudo-focal plane. This technique can be used as a method to characterize the degree of coherence of vortex beams. (paper)

  6. Electron beam propagation in the ion-focused and resistive regimes

    International Nuclear Information System (INIS)

    Hubbard, R.F.; Lampe, M.; Fernsler, R.; Slinker, S.P.

    1993-01-01

    Pinched propagation of intense relativistic electron beams occurs in several distinct pressure regimes. In low density gases (∼ 1-100 mtorr), the beam propagates in the ion-focused regime (IFR). The beam ionizes the neutral gas, and plasma electrons are ejected, leaving behind a positive ion column which pinches the beam electrostatically. At gas densities near 1 atm, the beam-generated plasma is resistive and the pinch effect is provided by the self-magnetic field of the beam. Beam transport experiments in both regimes have been performed on the Advanced Test Accelerator (ATA) at Lawrence Livermore National Lab. and on SuperIBEX at the Naval Research Lab. IFR methods have been employed in both experiments to transport the beam prior to injection into the air and to introduce a head-to-tail taper in the beam radius. IFR simulations have shown how the resulting beam radius and emittance profiles are influenced by gas density, chamber dimensions and entrance and exit foils. Beam propagation in dense gas is subject to disruption by the resistive hose instability. However, both experiments and simulations have shown that the emittance variation introduced by IFR transport can substantially reduce the growth of the hose instability. Both experiments have also propagated beams in reduced-density channels. Simulations predict that the channel may in some cases produce a moderate stabilizing and tracking effect arising from plasma currents flowing at the edge of the channel

  7. Matching bunched beams to alternating gradient focusing systems

    International Nuclear Information System (INIS)

    Lysenko, W.P.

    1980-07-01

    A numerical procedure for generating phase-space distributions matched to alternating gradient focusing systems has been tested. For a smooth-focusing system a matched distribution can be calculated. With a particle tracing simulation code such a distribution can be followed while adiabatically deforming the focusing forces until an alternating gradient configuration is reached. The distribution remains matched; that is, the final distribution is periodic with the structure period. This method is useful because it can produce distributions matched to nonlinear forces. This is a feature that elliptical distributions, with ellipse parameters obtained from the Courant-Snyder theory, do not have. External nonlinearities, including nonlinear couplings, were included in our examples but space charge was not. This procedure is expected to work with space charge but will require a three-dimensional space charge calculation in the simulation code

  8. About possibilities of obtaining focused beams of thermal neutrons of radionuclide source

    International Nuclear Information System (INIS)

    Aripov, G.A.; Kurbanov, B.I.; Sulaymanov, N.T.; Ergashev, A.

    2004-01-01

    Full text: In the last years significant progress is achieved in development of neutron focusing methods (concentrating neutrons in a given direction and a small area). In this, main attention is given to focusing of neutron beams of reactor, particularly cold neutrons and their applications. [1,2]. However, isotope sources also let obtain intensive neutron beams and solve quite important (tasks) problems (e.g. neutron capture therapy for malignant tumors) [3], and an actual problems is focusing of neutrons. We developed a device on the basis of californium source of neutrons, allowing to obtain focused (preliminarily) beam of thermal neutrons with the aid of respective choice of moderators, reflectors and geometry of their disposition. Here, fast neutrons and gamma rays in the beam are minimized. With the aid of the model we developed on the basis of Monte-Carlo method, it is possible to modify aforementioned device and dynamics of output neutrons in wide energy range and analyze ways of optimization of neutron beams of isotope sources with different neutron outputs. Device of preliminary focusing of thermal neutrons can serve as a basis for further focus of neutrons using micro- and nano-capillar systems. It is known that, capillary systems performed with certain technology can form beam of thermal neutrons increasing its density by more than two orders of magnitude and effectively divert beams up to 20 o with length of system 15 cm

  9. Effects of dispersion and longitudinal chromatic aberration on the focusing of isodiffracting pulsed Gaussian light beam

    International Nuclear Information System (INIS)

    Deng Dongmei; Guo Hong; Han Dingan; Liu Mingwei; Li Changfu

    2005-01-01

    Taking into account the dispersion and the longitudinal chromatic aberration (LCA) of the material of the lens, focusing of isodiffracting pulsed Gaussian light beam through single lens is analyzed. The smaller the cycle number of the isodiffracting pulsed Gaussian light beam is, the higher the order of the material dispersion should be considered

  10. Imperative function of electron beams in low-energy plasma focus ...

    Indian Academy of Sciences (India)

    A 2.2 kJ plasma focus device was analysed as an electron beam and an X-ray source that operates with argon gas refilled at a specific pressure. Time-resolved X-ray signals were observed using an array of PIN diode detectors, and the electron beam energy was detected using a scintillator-assisted photomultiplier tube.

  11. Remote nano-optical beam focusing lens by illusion optics

    Science.gov (United States)

    Margousi, David; Shoorian, Hamed Reza

    2014-08-01

    In this paper, as a new application of illusion optics, a nano-optical plasmonic focusing lens structure is proposed to manipulate the light remotely by employing illusion optics theory. Plasmonic nano-optic lenses that enable super-focusing beyond the diffraction limit have been proposed as an alternative to the conventional dielectric-based refractive lenses. In the presence of an illusion device, the electromagnetic plane-waves can penetrate into a metal layer and a clear focus appears. When the illusion device is removed, waves are blocked to transmit through the metal wall. In comparison with conventional methods, our proposed method avoids any physical changes or damages in the original structure. The proposed structure can be realized by isotropic layered materials, using effective medium theory. The special feature of the proposed structure and the device concepts introduced in this work gives it an opportunity to be used as a flexible element in ultrahigh nano-scale integrated circuits for miniaturization and tuning purposes.

  12. Development of nanometer resolution C-Band radio frequency beam position monitors in the Final Focus Test Beam

    Energy Technology Data Exchange (ETDEWEB)

    Slaton, T.; Mazaheri, G. [Stanford Univ., CA (US). Stanford Linear Accelerator Center; Shintake, T. [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

    1998-08-01

    Using a 47 GeV electron beam, the Final Focus Test Beam (FFTB) produces vertical spot sizes around 70 nm. These small beam sizes introduce an excellent opportunity to develop and test high resolution Radio Frequency Beam Position Monitors (RF-BPMs). These BPMs are designed to measure pulse to pulse beam motion (jitter) at a theoretical resolution of approximately 1 nm. The beam induces a TM{sub 110} mode with an amplitude linearly proportional to its charge and displacement from the BPM's (cylindrical cavity) axis. The C-band (5,712 MHz) TM{sub 110} signal is processed and converted into beam position for use by the Stanford Linear Collider (SLC) control system. Presented are the experimental procedures, acquisition, and analysis of data demonstrating resolution of jitter near 25 nm. With the design of future e{sup +}e{sup -} linear colliders requiring spot sizes close to 3 nm, understanding and developing RF-BPMs will be essential in resolving and controlling jitter.

  13. Estimation of blood velocity vectors using transverse ultrasound beam focusing and cross-correlation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Lacasa, Isabel Rodriguez

    1999-01-01

    Modern ultrasound scanners estimate the blood velocity by tracking the movement of the blood scatterers along the ultrasound beam. This is done by emitting pulsed ultrasound fields and finding the shift in position from pulse to pulse by correlating the received signals. Only the velocity component...... in a correlation estimator to find the velocity across the beam. This approach is extended in this paper by making beamforming along the direction of the flow. A fairly broad beam is emitted and the received signal is then focused along a selected direction. This direction can be along the ultrasound beam...

  14. Three-dimensional light distribution near the focus of a tightly focused beam of few-cycle optical pulses

    International Nuclear Information System (INIS)

    Romallosa, Kristine Marie; Bantang, Johnrob; Saloma, Caesar

    2003-01-01

    Via the Richards-Wolf vector diffraction theory, we analyze the three-dimensional intensity distribution of the focal volume that is produced by a strongly focused 750-nm beam of ultrafast, Gaussian-shaped optical pulses (10 -9 s≥ pulse width τ≥1 fs=10 -15 s). Knowledge of the three-dimensional distribution near focus is essential in determining the diffraction-limited resolution of an optical microscope. The optical spectrum of a short pulse is characterized by side frequencies about the carrier frequency. The effect of spectral broadening on the focused intensity distribution is evaluated via the Linfoot's criteria of fidelity, structural content, and correlation quality and with reference to a 750-nm cw focused beam. Different values are considered for τ and numerical aperture of the focusing lens (0.1≤X NA ≤1.2). At X NA =0.8, rapid deterioration of the focused intensity distribution is observed at τ=1.2 fs. This happens because a 750-nm optical pulse with τ=1.2 fs has an associated coherence length of 359.7 nm which is less than the Nyquist sampling interval of 375 nm that is required to sample 750 nm sinusoid without loss of information. The ill-effects of spectral broadening is weaker in two-photon excitation microscope than in its single-photon counterpart for the same focusing lens and light source

  15. Theoretical and Computational Investigation of Periodically Focused Intense Charged-Particle Beams

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chiping [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center

    2013-06-26

    The purpose of this report is to summarize results of theoretical and computational investigations of periodically focused intense charged-particle beams in parameter regimes relevant to the development of advanced high-brightness, high-power accelerators for high-energy physics research. The breakthroughs and highlights in our research in the period from April 1, 2010 to March 30, 2013 were: a) Theory and simulation of adiabatic thermal Child-Langmuir flow; b) Particle-in-cell simulations of adiabatic thermal beams in periodic solenoidal focusing field; c)Dynamics of charged particles in an adiabatic thermal beam equilibrium in a periodic solenoidal focusing field; d) Training of undergraduate researchers and graduate student in accelerator and beam physics. A brief introduction and summary is presented. Detailed descriptions of research results are provided in an appendix of publications at the end of the report.

  16. Beam profile control of line focus for x-ray laser experiment

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, G.Y.; Jitsuno, T.; Nakatsuka, M.; Daido, H.; Kato, Y.; Nakai, S. [Osaka Univ., Suita, Osaka (Japan). Inst. of Laser Engineering

    1995-12-31

    A high aspect ratio line focus on a target for the x-ray laser experiments is required for obtaining a high gain-length product. A new line focus system is developed to generate a uniform line focus. The system consists of a deformable mirror of a continuous faceplate type which provides an appropriate wavefront distribution for compensating an aberration of a line focus optics. The width and intensity distribution of 18.2mm long line focus have been improved on 2 times diffraction limit. As other application, a rectangular beam shaping from a circular defocused beam is investigated by the experiment and the diffraction calculation. The controllability of intensity distribution of laser beam by deformable mirror has been demonstrated.

  17. Controlling the optical fiber output beam profile by focused ion beam machining of a phase hologram on fiber tip.

    Science.gov (United States)

    Han, Jiho; Sparkes, Martin; O'Neill, William

    2015-02-01

    A phase hologram was machined on an optical fiber tip using a focused ion beam (FIB) system so that a ring-shaped beam emerges from the fiber tip. The fiber used for this work was a commercial single-mode optical fiber patch cable for a design wavelength of 633 nm with a germanosilicate core. The ring-shaped beam was chosen to ensure a simple geometry in the required phase hologram, though the Gerchberg-Saxton algorithm can be used to calculate a hologram for an arbitrary beam shape. The FIB machining took approximately 45 min at 30 kV and 200 pA. The radius of the resulting ring beam was 0.083 m at 1 m standoff, as compared to 0.1 m as was initially desired. Results suggest that this imaging technique may provide a basis for a beam-shaping method with several advantages over the current commercial solutions, having permanent alignment, compactness, and mechanical robustness. However, it would appear that minimizing the speckle pattern will remain a critical challenge for this technique to become widely implemented.

  18. Electron Acceleration by Beating of Two Intense Cross-Focused Hollow Gaussian Laser Beams in Plasma

    Science.gov (United States)

    Mahmoud, Saleh T.; Gauniyal, Rakhi; Ahmad, Nafis; Rawat, Priyanka; Purohit, Gunjan

    2018-01-01

    This paper presents propagation of two cross-focused intense hollow Gaussian laser beams (HGBs) in collisionless plasma and its effect on the generation of electron plasma wave (EPW) and electron acceleration process, when relativistic and ponderomotive nonlinearities are simultaneously operative. Nonlinear differential equations have been set up for beamwidth of laser beams, power of generated EPW, and energy gain by electrons using WKB and paraxial approximations. Numerical simulations have been carried out to investigate the effect of typical laser-plasma parameters on the focusing of laser beams in plasmas and further its effect on power of excited EPW and acceleration of electrons. It is observed that focusing of two laser beams in plasma increases for higher order of hollow Gaussian beams, which significantly enhanced the power of generated EPW and energy gain. The amplitude of EPW and energy gain by electrons is found to enhance with an increase in the intensity of laser beams and plasma density. This study will be useful to plasma beat wave accelerator and in other applications requiring multiple laser beams. Supported by United Arab Emirates University for Financial under Grant No. UPAR (2014)-31S164

  19. Electron beam propagation in the ion focused regime (IFR) with the experimental test accelerator (ETA)

    International Nuclear Information System (INIS)

    Struve, K.W.; Lauer, E.J.; Chambers, F.W.

    1983-01-01

    The IFR is a well-known stable, low pressure (0.10 to 0.120 torr in air) propagation window. Secondary electrons created by collisions of beam electrons with gas atoms are rapidly expelled by the strong radial electric field of the beam charge. The ions that remain inside the beam partially neutralize the electric field, allowing magnetic pinch forces to focus the beam. Experiments with the ETA beam have re-verified this stable window and are reported. Image forces from a close wall IFR propagation tank are also experimentally shown to center the beam and damp transverse oscillations. Results of experiments using 5 and 15 cm dia beam tubes are reported. For p tau > 2 torr-nsec (gas pressure x time into pulse the beam charge becomes completely neutralized by the ions, allowing a build up of plasma and resultant beam-plasma instabilities. The onset of these instabilities has been measured using rf pickup loops (0 to 2 GHz) and microwave detectors (6 to 40 GHz), and are also reported

  20. Optical simulation of laser beam phase-shaping focusing optimization in biological tissues

    Science.gov (United States)

    Gomes, Ricardo; Vieira, Pedro; Coelho, João. M. P.

    2013-11-01

    In this paper we report the development of an optical simulator that can be used in the development of methodologies for compensate/decrease the light scattering effect of most biological tissues through phase-shaping methods. In fact, scattering has long been a major limitation for the medical applications of lasers where in-depth tissues concerns due to the turbid nature of most biological media in the human body. In developing the simulator, two different approaches were followed: one using multiple identical beams directed to the same target area and the other using a phase-shaped beam. In the multiple identical beams approach (used mainly to illustrate the limiting effect of scattering on the beam's propagation) there was no improvement in the beam focus at 1 mm compared to a single beam layout but, in phase-shaped beam approach, a 8x improvement on the radius of the beam at the same depth was achieved. The models were created using the optical design software Zemax and numerical algorithms created in Matlab programming language to shape the beam wavefront. A dedicated toolbox allowed communication between both programs. The use of the two software's proves to be a simple and powerful solution combining the best of the two and allowing a significant potential for adapting the simulations to new systems and thus allow to assess their response and define critical engineering parameters prior to laboratorial implementation.

  1. Present Status And First Results of the Final Focus Beam Line at the KEK Accelerator Test Facility

    Energy Technology Data Exchange (ETDEWEB)

    Bambade, P.; /Orsay /KEK, Tsukuba; Alabau Pons, M.; /Valencia U., IFIC; Amann, J.; /SLAC; Angal-Kalinin, D.; /Daresbury; Apsimon, R.; /Oxford U., JAI; Araki, S.; Aryshev, A.; /KEK, Tsukuba; Bai, S.; /Beijing, Inst. High Energy Phys.; Bellomo, P.; /SLAC; Bett, D.; /Oxford U., JAI; Blair, G.; /Royal Holloway, U. of London; Bolzon, B.; /Savoie U.; Boogert, S.; Boorman, G.; /Royal Holloway, U. of London; Burrows, P.N.; Christian, G.; Coe, P.; Constance, B.; /Oxford U., JAI; Delahaye, Jean-Pierre; /CERN; Deacon, L.; /Royal Holloway, U. of London; Elsen, E.; /DESY /Valencia U., IFIC /KEK, Tsukuba /Beijing, Inst. High Energy Phys. /Savoie U. /Fermilab /Ecole Polytechnique /KEK, Tsukuba /Kyungpook Natl. U. /KEK, Tsukuba /Pohang Accelerator Lab. /Kyoto U., Inst. Chem. Res. /Savoie U. /Daresbury /Tokyo U. /Royal Holloway, U. of London /Kyungpook Natl. U. /Pohang Accelerator Lab. /Tokyo U. /KEK, Tsukuba /SLAC /University Coll. London /KEK, Tsukuba /SLAC /Royal Holloway, U. of London /KEK, Tsukuba /Tokyo U. /SLAC /Tohoku U. /KEK, Tsukuba /Tokyo U. /Pohang Accelerator Lab. /Brookhaven /SLAC /Oxford U., JAI /SLAC /Orsay /KEK, Tsukuba /Oxford U., JAI /Orsay /Fermilab /Tohoku U. /Manchester U. /CERN /SLAC /Tokyo U. /KEK, Tsukuba /Oxford U., JAI /Hiroshima U. /KEK, Tsukuba /CERN /KEK, Tsukuba /Oxford U., JAI /Ecole Polytechnique /SLAC /Oxford U., JAI /Fermilab /SLAC /Liverpool U. /SLAC /Tokyo U. /SLAC /Tokyo U. /KEK, Tsukuba /SLAC /CERN

    2011-11-11

    ATF2 is a final-focus test beam line which aims to focus the low emittance beam from the ATF damping ring to a vertical size of about 37 nm and to demonstrate nanometer level beam stability. Several advanced beam diagnostics and feedback tools are used. In December 2008, construction and installation were completed and beam commissioning started, supported by an international team of Asian, European, and U.S. scientists. The present status and first results are described.

  2. Three-Dimensional Simulations of Electron Beams Focused by Periodic Permanent Magnets

    Science.gov (United States)

    Kory, Carol L.

    1999-01-01

    A fully three-dimensional (3D) model of an electron beam focused by a periodic permanent magnet (PPM) stack has been developed. First, the simulation code MAFIA was used to model a PPM stack using the magnetostatic solver. The exact geometry of the magnetic focusing structure was modeled; thus, no approximations were made regarding the off-axis fields. The fields from the static solver were loaded into the 3D particle-in-cell (PIC) solver of MAFIA where fully 3D behavior of the beam was simulated in the magnetic focusing field. The PIC solver computes the time-integration of electromagnetic fields simultaneously with the time integration of the equations of motion of charged particles that move under the influence of those fields. Fields caused by those moving charges are also taken into account; thus, effects like space charge and magnetic forces between particles are fully simulated. The electron beam is simulated by a number of macro-particles. These macro-particles represent a given charge Q amounting to that of several million electrons in order to conserve computational time and memory. Particle motion is unrestricted, so particle trajectories can cross paths and move in three dimensions under the influence of 3D electric and magnetic fields. Correspondingly, there is no limit on the initial current density distribution of the electron beam, nor its density distribution at any time during the simulation. Simulation results including beam current density, percent ripple and percent transmission will be presented, and the effects current, magnetic focusing strength and thermal velocities have on beam behavior will be demonstrated using 3D movies showing the evolution of beam characteristics in time and space. Unlike typical beam optics models, this 3D model allows simulation of asymmetric designs such as non- circularly symmetric electrostatic or magnetic focusing as well as the inclusion of input/output couplers.

  3. Ion beam analysis techniques for the elemental fingerprinting of fine particle smoke from vegetation burning in NSW

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, D. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1996-12-31

    Accelerator based ion beam analysis (IBA) techniques, including PIXE, PIGME, RBS and PESA, have been used to analyse elemental compositions of airborne particles covering a 60,000 square kilometres area of Wollongong, Sydney and Newcastle. These IBA techniques provide elemental concentrations for over 20 different elements from hydrogen to lead, they include H, C, N, O, F, Na, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Cu, Ni, Zn, Br and Pb. The four ion beam techniques are performed simultaneously on the 3MV Van de Graaff accelerator at ANSTO and have been described in detail elsewhere. They are sufficiently sensitive to analyse for many of these elements to levels around 10 ng/m{sup 3} or less in about five minutes of accelerator running time per filter. This is more than adequate for aerosol analyses as most filters contain around 150 {mu}g/cm{sup 2} of material which corresponds to about 10{mu}g/m{sup 3} of fine particles in the atmosphere. For this work fine particles are those with diameters less than 2.5{mu}m. Fine particle data has been collected twice a week and analysed for each of the above elements by ANSTO since 1991 at more than 25 different sites throughout NSW. This large dataset set allows us to not only determine the composition of fine particles and to look for signature elements for particular sources but also to use multivariate statistics to define elemental source fingerprints and then to determine the percentage contributions of these fingerprints to the total fine particle mass in the atmosphere. This paper describes the application of these techniques to the study of domestic wood fires and vegetation burning in NSW over a two year period from 1992-93. It also presents, for the first time, fine particle data related to the January 1994 bushfires in NSW. 6 refs., 1 tab., 5 figs.

  4. Ion beam analysis techniques for the elemental fingerprinting of fine particle smoke from vegetation burning in NSW

    International Nuclear Information System (INIS)

    Cohen, D.

    1996-01-01

    Accelerator based ion beam analysis (IBA) techniques, including PIXE, PIGME, RBS and PESA, have been used to analyse elemental compositions of airborne particles covering a 60,000 square kilometres area of Wollongong, Sydney and Newcastle. These IBA techniques provide elemental concentrations for over 20 different elements from hydrogen to lead, they include H, C, N, O, F, Na, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Cu, Ni, Zn, Br and Pb. The four ion beam techniques are performed simultaneously on the 3MV Van de Graaff accelerator at ANSTO and have been described in detail elsewhere. They are sufficiently sensitive to analyse for many of these elements to levels around 10 ng/m 3 or less in about five minutes of accelerator running time per filter. This is more than adequate for aerosol analyses as most filters contain around 150 μg/cm 2 of material which corresponds to about 10μg/m 3 of fine particles in the atmosphere. For this work fine particles are those with diameters less than 2.5μm. Fine particle data has been collected twice a week and analysed for each of the above elements by ANSTO since 1991 at more than 25 different sites throughout NSW. This large dataset set allows us to not only determine the composition of fine particles and to look for signature elements for particular sources but also to use multivariate statistics to define elemental source fingerprints and then to determine the percentage contributions of these fingerprints to the total fine particle mass in the atmosphere. This paper describes the application of these techniques to the study of domestic wood fires and vegetation burning in NSW over a two year period from 1992-93. It also presents, for the first time, fine particle data related to the January 1994 bushfires in NSW. 6 refs., 1 tab., 5 figs

  5. Bunch-length and beam-timing monitors in the SLC final focus

    International Nuclear Information System (INIS)

    Zimmermann, F.; Yocky, G.; Whittum, D.H.; Seidel, M.; Ng, C.K.; McCormick, D.; Bane, K.L.F.

    1998-07-01

    During the 1997/98 luminosity run of the Stanford Linear Collider (SLC), two novel RF-based detectors were brought into operation, in order to monitor the interaction-point (IP) bunch lengths and fluctuations in the relative arrival time of the two colliding beams. Both bunch length and timing can strongly affect the SLC luminosity and had not been monitored in previous years. The two new detectors utilize a broad-band microwave signal, which is excited by the beam through a ceramic gap in the final-focus beam pipe and transported outside of the beam line vault by a 160-ft long X-Band waveguide. The authors describe the estimated luminosity reduction due to bunch-length drift and IP timing fluctuation, the monitor layout, the expected responses and signal levels, calibration measurements, and beam observations

  6. Fine structure of modal focusing effect in a three dimensional plasma-sheath-lens formed by disk electrodes

    DEFF Research Database (Denmark)

    Stamate, Eugen; Yamaguchi, Masahito

    2015-01-01

    Modal and discrete focusing effects associated with three-dimensional plasma-sheath-lenses show promising potential for applications in ion beam extraction, mass spectrometry, plasma diagnostics and for basic studies of plasma sheath. The ion focusing properties can be adjusted by controlling the...... to the sheath thickness and can be used to monitor very small changes in plasma parameters. Three dimensional simulations are found to be in very good agreement with experiments....

  7. Time-resolved characteristics of deuteron-beam generated by plasma focus discharge

    Science.gov (United States)

    Bradley, D. A.

    2018-01-01

    The plasma focus device discussed herein is a Z-pinch pulsed-plasma arrangement. In this, the plasma is heated and compressed into a cylindrical column, producing a typical density of > 1025 particles/m3 and a temperature of (1–3) × 107 oC. The plasma focus has been widely investigated as a radiation source, including as ion-beams, electron-beams and as a source of x-ray and neutron production, providing considerable scope for use in a variety of technological situations. Thus said, the nature of the radiation emission depends on the dynamics of the plasma pinch. In this study of the characteristics of deuteron-beam emission, in terms of energy, fluence and angular distribution were analyzed. The 2.7 kJ plasma focus discharge has been made to operate at a pressure of less than 1 mbar rather than at its more conventional operating pressure of a few mbar. Faraday cup were used to determine deuteron-beam energy and deuteron-beam fluence per shot while CR-39 solid-state nuclear track detectors were employed in studying the angular distribution of deuteron emission. Beam energy and deuteron-beam fluence per shot have been found to be pressure dependent. The largest value of average deuteron energy measured for present conditions was found to be (52 ± 7) keV, while the deuteron-beam fluence per shot was of the order of 1015 ions/m2 when operated at a pressure of 0.2 mbar. The deuteron-beam emission is in the forward direction and is observed to be highly anisotropic. PMID:29309425

  8. Collective Focusing of Intense Ion Beam Pulses for High-energy Density Physics Applications

    International Nuclear Information System (INIS)

    Dorf, Mikhail A.; Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.

    2011-01-01

    The collective focusing concept in which a weak magnetic lens provides strong focusing of an intense ion beam pulse carrying a neutralizing electron background is investigated by making use of advanced particle-in-cell simulations and reduced analytical models. The original analysis by Robertson Phys. Rev. Lett. 48, 149 (1982) is extended to the parameter regimes of particular importance for several high-energy density physics applications. The present paper investigates (1) the effects of non-neutral collective focusing in a moderately strong magnetic field; (2) the diamagnetic effects leading to suppression of the applied magnetic field due to the presence of the beam pulse; and (3) the influence of a finite-radius conducting wall surrounding the beam cross-section on beam neutralization. In addition, it is demonstrated that the use of the collective focusing lens can significantly simplify the technical realization of the final focusing of ion beam pulses in the Neutralized Drift Compression Experiment-I (NDCX-I), and the conceptual designs of possible experiments on NDCX-I are investigated by making use of advanced numerical simulations.

  9. Note: Optical fiber milled by focused ion beam and its application for Fabry-Pérot refractive index sensor

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Wang, Fei; Savenko, Alexey

    2011-01-01

    We introduce a highly compact fiber-optic Fabry-Pérot refractive index sensor integrated with a fluid channel that is fabricated directly near the tip of a 32 μm in diameter single-mode fiber taper. The focused ion beam technique is used to efficiently mill the microcavity from the fiber side...... and finely polish the end facets of the cavity with a high spatial resolution. It is found that a fringe visibility of over 15 dB can be achieved and that the sensor has a sensitivity of ∼1731 nm/RIU (refractive index units) and a detection limit of ∼5.78 × 10−6 RIU. This miniature integrated all-in-fiber...

  10. Development of Focused Ion Beam technique for high speed steel 3D-SEM artefact fabrication

    DEFF Research Database (Denmark)

    Carli, Lorenzo; MacDonald, A. Nicole; De Chiffre, Leonardo

    2009-01-01

    The work describes preliminary manufacture by grinding, followed by machining on a Focused Ion Beam (FIB), of a high speed steel step artefact for 3D-SEM calibration. The FIB is coupled with a SEM in the so called dual beam instrument. The milling capabilities of FIB were checked from a qualitative...... point of view, using the dual beam SEM imaging, and quantitatively using a reference stylus instrument, to establish traceability. A triangular section having a depth of about 10 μm was machined, where the 50 μm curvature radius due to grinding was reduced to about 2 μm by FIB milling...

  11. Comparing different approaches to characterization of focused X-ray laser beams

    Czech Academy of Sciences Publication Activity Database

    Chalupský, Jaromír; Boháček, Pavel; Hájková, Věra; Hau-Riege, S.P.; Heimann, P.A.; Juha, Libor; Krzywinski, J.; Messerschmidt, M.; Moeller, S.P.; Nagler, B.; Rowen, M.; Schlotter, W.F.; Swiggers, M.L.; Turner, J.J.

    2011-01-01

    Roč. 631, č. 1 (2011), s. 130-133 ISSN 0168-9002 R&D Projects: GA AV ČR KAN300100702; GA MŠk LC510; GA MŠk(CZ) LC528; GA ČR GAP208/10/2302; GA MŠk LA08024; GA AV ČR IAAX00100903; GA MŠk(CZ) ME10046 Institutional research plan: CEZ:AV0Z10100523 Keywords : X-ray laser * X-ray ablation * beam focusing * beam characterization * beam profile measurement Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.207, year: 2011

  12. Simulation of topography evolution and damage formation during TEM sample preparation using focused ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Boxleitner, W. E-mail: wini@hobbit.fke.tuwien.ac.at; Hobler, G.; Klueppel, V.; Cerva, H

    2001-04-01

    Our recently developed simulation code FIBSIM is applied to topics related to transmission electron microscopy (TEM) sample preparation using focused ion beams (FIB). FIBSIM combines dynamic Monte Carlo simulation of collision cascades with two-dimensional, cell-based topography simulation. The influence of the scanning mode and of the beam current profile on the evolution of the surface contour is investigated. Furthermore, amorphous zones in silicon samples and damaged regions are predicted for different beam energies of 10, 30 and 50 keV. The thickness of the predicted amorphous regions is in good agreement with experimental TEM data.

  13. Focused transport of intense charged particle beams. Final technical report FY/93

    International Nuclear Information System (INIS)

    1997-01-01

    Many recent developments in accelerator technology have increased the need for a better understanding of the physics of intense-beam transport. Of particular interest to the work described here is the appearance, as beam intensities are increased, of a class of nonlinear phenomena which involve the collective interaction of the beam particles. Beam intensity, used as a measure of the importance of space-charge collective behavior, depends on the ratio of current to emittance. The nonlinear beam dynamics, and any resulting emittance growth, which are characteristic of the intense-beam regime, can therefore occur even at low currents in any accelerator system with sufficiently high intensity, especially in the low beta section. Furthermore, since emittance of a beam is difficult to reduce, the ultimate achievement of necessary beam luminosities requires the consideration of possible causes of longitudinal and transverse emittance growth at every stage of the beam lifetime. The research program described here has addressed the fundamental physics which comes into play during the transport, acceleration and focusing of intense beams. Because of the long term and ongoing nature of the research program discussed here, this report is divided into two sections. The first section constitutes a long term revue of the accomplishments which have resulted from the research effort reported, especially in pioneering the use of particle-in-cell (PIC) computer simulation techniques for simulation of the dynamics of space-charge-dominated beams in particle accelerators. The following section emphasizes, in more detail, the accomplishments of the FY 92/93 period immediately prior to the termination of this particular avenue of support. 41 refs

  14. Focusing and bunching of ion beam in axial injection channel of IPHC cyclotron TR24

    Science.gov (United States)

    Adam, T.; Ivanenko, I.; Kazarinov, N.; Osswald, F.; Traykov, E.

    2017-07-01

    The CYRCe cyclotron (CYclotron pour la ReCherche et l’Enseignement) is used at IPHC (Institut Pluridisciplinaire Hubert Curien) for the production of radio-isotopes for diagnostics, medical treatments and fundamental research in radiobiology. The TR24 cyclotron produced and commercialized by ACSI (Canada) delivers a 16-25 MeV proton beam with intensity from few nA up to 500 μA. The solenoidal focusing instead of existing quadrupole one is proposed in this report. The changing of the focusing elements will give the better beam matching with the acceptance of the spiral inflector of the cyclotron. The parameters of the focusing solenoid are found. Additionally, the main parameters of the bunching system are evaluated in the presence of the beam space charge. This system consists of the buncher installed in the axial injection beam line of the cyclotron. The using of the grid-less multi harmonic buncher may increase the accelerated beam current and will give the opportunity to new proton beam applications.

  15. Needle-like focus generation by radially polarized halo beams emitted by photonic-crystal ring-cavity laser

    Science.gov (United States)

    Kitamura, Kyoko; Nishimoto, Masaya; Sakai, Kyosuke; Noda, Susumu

    2012-11-01

    Focused fields that possess a small spot size and long depth of focus (DOF) are expected to lead to the further development of optical applications. Here, we develop a photonic-crystal ring-cavity laser that emits a beam with a radially polarized halo shape (rinner/router > 0.9). This beam has a needle-like focus with a spot size of less than 0.4λ and a depth of focus longer than 10 λ for a 0.9 numerical aperture objective lens. We evaluate the focusing properties of the emitted beam and demonstrate that it has a longer depth of focus than conventional beams.

  16. Design of titania nanotube structures by focused laser beam direct writing

    International Nuclear Information System (INIS)

    Enachi, Mihai; Stevens-Kalceff, Marion A.; Sarua, Andrei; Ursaki, Veaceslav; Tiginyanu, Ion

    2013-01-01

    In this work, we report on electrochemical fabrication of titania films consisting of nanotubes (NTs) and their treatment by focused laser beam. The results of sample characterization by optical and scanning electron microscopy, cathodoluminescence imaging, and Raman scattering scanning spectroscopy are compared to those inherent to specimens subjected to thermal treatment in a furnace. The obtained data demonstrate possibilities for controlling crystallographic structure of TiO 2 NTs by focused laser beam direct writing. These findings open new prospects for the design and fabrication of spatial architectures based on titania nanotubes

  17. Motion-free hybrid design laser beam propagation analyzer using a digital micromirror device and a variable focus liquid lens.

    Science.gov (United States)

    Sheikh, Mumtaz; Riza, Nabeel A

    2010-06-01

    To the best of our knowledge, we propose the first motion-free laser beam propagation analyzer with a hybrid design using a digital micromirror device (DMD) and a liquid electronically controlled variable focus lens (ECVFL). Unlike prior analyzers that require profiling the beam at multiple locations along the light propagation axis, the proposed analyzer profiles the beam at the same plane for multiple values of the ECVFL focal length, thus eliminating beam profiler assembly motion. In addition to measuring standard Gaussian beam parameters, the analyzer can also be used to measure the M(2) beam propagation parameter of a multimode beam. Proof-of-concept beam parameter measurements with the proposed analyzer are successfully conducted for a 633 nm laser beam. Given the all-digital nature of the DMD-based profiling and all-analog motion-free nature of the ECVFL beam focus control, the proposed analyzer versus prior art promises better repeatability, speed, and reliability.

  18. Pink-beam focusing with a one-dimensional compound refractive lens.

    Science.gov (United States)

    Dufresne, Eric M; Dunford, Robert W; Kanter, Elliot P; Gao, Yuan; Moon, Seoksu; Walko, Donald A; Zhang, Xusheng

    2016-09-01

    The performance of a cooled Be compound refractive lens (CRL) has been tested at the Advanced Photon Source (APS) to enable vertical focusing of the pink beam and permit the X-ray beam to spatially overlap with an 80 µm-high low-density plasma that simulates astrophysical environments. Focusing the fundamental harmonics of an insertion device white beam increases the APS power density; here, a power density as high as 500 W mm(-2) was calculated. A CRL is chromatic so it does not efficiently focus X-rays whose energies are above the fundamental. Only the fundamental of the undulator focuses at the experiment. A two-chopper system reduces the power density on the imaging system and lens by four orders of magnitude, enabling imaging of the focal plane without any X-ray filter. A method to measure such high power density as well as the performance of the lens in focusing the pink beam is reported.

  19. Aberrations due to solenoid focusing of a multiply charged high-current ion beam

    CERN Document Server

    Grégoire, G; Lisi, N; Schnuriger, J C; Scrivens, R; Tambini, J

    2000-01-01

    At the output of a laser ion source, a high current of highly charged ions with a large range of charge states is available. The focusing of such a beam by magnetic elements causes a nonlinear space-charge field to develop which can induce large aberrations and emittance growth in the beam. Simulation of the beam from the CERN laser ion source will be presented for an ideal magnetic and electrostatic system using a radially symmetric model. In addition, the three dimensional software KOBRA3 is used for the simulation of the solenoid line. The results of these simulations will be compared with experiments performed on the CERN laser ion source with solenoids (resulting in a hollow beam) and a series of gridded electrostatic lenses. (5 refs).

  20. Design of a wiggler-focused, sheet beam X band klystron

    International Nuclear Information System (INIS)

    Eppley, K.R.; Herrmannsfeldt, W.B.; Miller, R.H.

    1987-02-01

    An X band klystron using a sheet beam and wiggler focusing was simulated using the 2 + 1/2 dimensional particle in cell code MASK. Simulation of the rf cavities was by means of the port approximation used in modelling of standard klystrons. The wigglers, which would need permanent magnets to achieve the required field strengths, were modelled using an idealized analytic expression with an exponential rise and a linear taper superimposed on a sinusoidal variation. Cavity locations and tunings were varied for maximum output power. Beam voltage and current were also varied to explore the effect on efficiency. Both an idealized laminar beam and a more realistic beam from a gun design code were studied. For a voltage of 200 kV and current of 20 amp per linear cm efficiencies of approximately 50% were calculated

  1. Processes in a dense long-pulse electron beam focused on a solid target

    International Nuclear Information System (INIS)

    Arkhipov, A.V.; Sominskij, G.G.

    1996-01-01

    The results obtained in beam-target experiments with dense medium-energy electron beam in the regime of long single pulses are presented. The measured power density of the focused beam at the target reached 20 MW/cm 2 in these experiments. The processes caused by dense flows of secondary particles and by a dense target ablation plasma were studied in detail. Substantial target shielding occurs when the energy density at the target exceeds the value of about 1 kJ/cm 2 . The target plasma and the sputtered matter that is responsible for shielding affects also the beam structure, as well as the target etching rates. (J.U.). 3 figs., 5 refs

  2. Design of optics for the final focus test beam at SLAC

    International Nuclear Information System (INIS)

    Oide, Katsunobu.

    1989-05-01

    The goal of the Final Focus Test Beam experiment (FFTB) is to produce an electron beam spot of 1 μm by 60 nm in transverse dimensions. In the future linear collider of TeV region (TLC), a typical spot size of 100 nm by 1 nm at the interaction point is required to get luminosity of 1 /times/ 10 34 cm/sup /minus/2/s/sup /minus/1/. This spot size is about 1/1000 of the SLC in the vertical dimension, and is demanding for an optics design, alignments, beam diagnostics, and tuning procedures. The spot size of the FFTB will be an important next step from the SLC toward the TLC. This paper describes the design of the beam optics. 11 refs., 2 figs., 1 tab

  3. Measurements of the evaporation and hygroscopic response of single fine-mode aerosol particles using a Bessel beam optical trap.

    Science.gov (United States)

    Cotterell, Michael I; Mason, Bernard J; Carruthers, Antonia E; Walker, Jim S; Orr-Ewing, Andrew J; Reid, Jonathan P

    2014-02-07

    A single horizontally-propagating zeroth order Bessel laser beam with a counter-propagating gas flow was used to confine single fine-mode aerosol particles over extended periods of time, during which process measurements were performed. Particle sizes were measured by the analysis of the angular variation of light scattered at 532 nm by a particle in the Bessel beam, using either a probe beam at 405 nm or 633 nm. The vapour pressures of glycerol and 1,2,6-hexanetriol particles were determined to be 7.5 ± 2.6 mPa and 0.20 ± 0.02 mPa respectively. The lower volatility of hexanetriol allowed better definition of the trapping environment relative humidity profile over the measurement time period, thus higher precision measurements were obtained compared to those for glycerol. The size evolution of a hexanetriol particle, as well as its refractive index at wavelengths 532 nm and 405 nm, were determined by modelling its position along the Bessel beam propagation length while collecting phase functions with the 405 nm probe beam. Measurements of the hygroscopic growth of sodium chloride and ammonium sulfate have been performed on particles as small as 350 nm in radius, with growth curves well described by widely used equilibrium state models. These are the smallest particles for which single-particle hygroscopicity has been measured and represent the first measurements of hygroscopicity on fine mode and near-accumulation mode aerosols, the size regimes bearing the most atmospheric relevance in terms of loading, light extinction and scattering. Finally, the technique is contrasted with other single particle and ensemble methods, and limitations are assessed.

  4. Low emittance design of the electron gun and the focusing channel of the Compact Linear Collider drive beam

    Directory of Open Access Journals (Sweden)

    M. Dayyani Kelisani

    2017-04-01

    Full Text Available For the Compact Linear Collider project at CERN, the power for the main linacs is extracted from a drive beam generated from a high current electron source. The design of the electron source and its subsequent focusing channel has a great impact on the beam dynamic considerations of the drive beam. We report the design of a thermionic electron source and the subsequent focusing channels with the goal of production of a high quality beam with a very small emittance.

  5. An inexpensive electron beam annealing apparatus with line focus, made from a converted electron welding machine

    International Nuclear Information System (INIS)

    Krimmel, E.F.; Lutsch, AG.K.; Meyer, H.P.; Theron, S.B.K.

    1985-01-01

    Electron beam annealing has, after an active period of research, become an established technology in the production of semiconductor devices, since high quality restoration practically without out-diffusion, can be achieved. Many universities and research institutions cannot afford to purchase a dedicated electron beam annealing apparatus. In the following a conversion of an industrial electron beam welding apparatus into an annealing apparatus with line focus is described, which could easily be copied by interested institutions. A magnetic quadrupole-lens is described which converts the point into a line focus. Standard-TV deflections with a special generator circuit for the X and Y deflection are used. Electron currents of 4 to 5 mA cause silicon to melt (1415 deg C). Annealing results obtained with the apparatus are discussed. (author)

  6. Determination of Cross-Sectional Area of Focused Picosecond Gaussian Laser Beam

    Science.gov (United States)

    Ledesma, Rodolfo; Fitz-Gerald, James; Palmieri, Frank; Connell, John

    2018-01-01

    Measurement of the waist diameter of a focused Gaussian-beam at the 1/e(sup 2) intensity, also referred to as spot size, is key to determining the fluence in laser processing experiments. Spot size measurements are also helpful to calculate the threshold energy and threshold fluence of a given material. This work reports an application of a conventional method, by analyzing single laser ablated spots for different laser pulse energies, to determine the cross-sectional area of a focused Gaussian-beam, which has a nominal pulse width of approx. 10 ps. Polished tungsten was used as the target material, due to its low surface roughness and low ablation threshold, to measure the beam waist diameter. From the ablative spot measurements, the ablation threshold fluence of the tungsten substrate was also calculated.

  7. High-resolution direct-write patterning using focused ion beams

    NARCIS (Netherlands)

    Ocola, L.E.; Rue, C.; Maas, D.J.

    2014-01-01

    Over the last few years, significant improvements in sources, columns, detectors, control software, and accessories have enabled a wealth of new focused ion beam applications. In addition, modeling has provided many insights into ion-sample interactions and the resultant effects on the sample. With

  8. Focused-ion-beam nano-structuring of photonic cavities in dielectric materials

    NARCIS (Netherlands)

    Ay, F.; Pollnau, Markus

    Focused ion beam (FIB) milling is an emerging technology that enables fast, reliable and well-controlled nanometer-size feature definition. In this work we will discuss applications of the tool in the area of photonics. The FIB technique can be adapted and optimized almost for any material system

  9. Performance of Focused Ion Beam Trimmed Yoke-Type Magnetoresistive Heads for Magnetic Microscopy

    NARCIS (Netherlands)

    Phillips, G.N.; Eisenberg, M.; Eisenberg, Martin; Draaisma, Eddie A.; Abelmann, Leon; Lodder, J.C.

    2002-01-01

    Thin-film yoke-type magnetoresistive (MR) tape heads with eight channels have been used for scanning mag-netoresistance microscopy. The NiFe read flux guides of the channels have been trimmed down from 12 um to widths varying between 5 um and 100 nm by focused ion-beam milling with Ga+ions. The

  10. Charging effects during focused electron beam induced deposition of silicon oxide

    NARCIS (Netherlands)

    de Boer, Sanne K.; van Dorp, Willem F.; De Hosson, Jeff Th. M.

    2011-01-01

    This paper concentrates on focused electron beam induced deposition of silicon oxide. Silicon oxide pillars are written using 2, 4, 6, 8, 10-pentamethyl-cyclopenta-siloxane (PMCPS) as precursor. It is observed that branching of the pillar occurs above a minimum pillar height. The branching is

  11. Portable test bench for the studies concerning ion sources and ion beam extraction and focusing systems

    International Nuclear Information System (INIS)

    Cordero Lopez, F.

    1961-01-01

    A portable test bench is described, which was designed to check ion sources, ion beam extraction and focusing systems before its use in a 600 KeV Cockcroft-Walton accelerator. The vacuum possibilities of the system are specially analyzed in connection with its particular use. The whole can be considered as a portable accelerator of low energy (50 keV). (Author)

  12. Radial focusing of a relativistic electron beam in a bipotential electrostatic lens

    International Nuclear Information System (INIS)

    Genoni, T.C.

    1994-01-01

    The focusing of a relativistic electron beam in a bipotential electrostatic lens is discussed. An iterative scheme for the solution of the paraxial ray equation is used to derive approximate analytic formulas for the lens parameters and lens transfer matrix elements. The formulas are compared to results of direct numerical integration of the paraxial ray equation

  13. In Situ Tuning of Focused-Ion-Beam Defined Nanomechanical Resonators Using Joule Heating

    DEFF Research Database (Denmark)

    Homann, Lasse Vinther; Booth, Tim; Lei, Anders

    2011-01-01

    Nanomechanical resonators have a huge potential for a variety of applications, including high-resolution mass sensing. In this paper, we demonstrate a novel rapid prototyping method for fabricating nanoelectromechanical systems using focused-ion-beam milling as well as in situ electromechanical c...

  14. Ultrahigh resolution focused electron beam induced processing: the effect of substrate thickness

    DEFF Research Database (Denmark)

    van Dorp, Willem F; Lazic, Ivan; Beyer, André

    2011-01-01

    It is often suggested that the growth in focused electron beam induced processing (FEBIP) is caused not only by primary electrons, but also (and even predominantly) by secondary electrons (SEs). If that is true, the growth rate for FEBIP can be changed by modifying the SE yield. Results from our ...

  15. Dynamics of cavitation clouds within a high-intensity focused ultrasonic beam

    NARCIS (Netherlands)

    Lu, Yuan; Katz, Joseph; Prosperetti, Andrea

    2013-01-01

    In this experimental study, we generate a 500 kHz high-intensity focused ultrasonic beam, with pressure amplitude in the focal zone of up to 1.9 MPa, in initially quiescent water. The resulting pressure field and behavior of the cavitation bubbles are measured using high-speed digital in-line

  16. Imperative function of electron beams in low-energy plasma focus ...

    Indian Academy of Sciences (India)

    2015-04-12

    Apr 12, 2015 ... cylinder as the anode with 1.9 cm diameter and 18 cm effective length. The hollow anode was used in the experiment to observe the energetic electron beam in the plasma focus device. The outer electrode consisted of a group of six copper rods that formed a shape of a squirrel cage with an inner diameter ...

  17. Acceleration and Focusing of Electrons and Positrons Using a 30 GeV Drive Beam

    International Nuclear Information System (INIS)

    Hogan, Mark J

    2003-01-01

    A series of plasma wakefield acceleration (PWFA) experiments are being conducted with a 30 GeV drive beam from the Stanford Linear Accelerator Center (SLAC). These experiments continue to address the application of meter-scale plasmas to focus and accelerate electrons and positrons in the context of future applications to high-energy accelerators

  18. Focused Ion Beam Nanotomography of ruthenium-bearing nickel-base superalloys with focus on cast-microstructure and phase stability; Focused Ion Beam Nanotomographie von rutheniumhaltigen Nickelbasis-Superlegierungen mit Fokus auf Gussgefuege und Phasenstabilitaet

    Energy Technology Data Exchange (ETDEWEB)

    Cenanovic, Samir

    2012-12-03

    The influence of rhenium and ruthenium on the multi component system nickel-base superalloy is manifold and complex. An experimental nickel-base superalloy containing rhenium and ruthenium within defined contents, named Astra, was used to investigate the influences of these two elements on the alloy system. The last stage solidification of nickel-base superalloys after Bridgman casting and the high temperature phase stability of these alloys, could be explored with the aid of focused ion beam nanotomography. FIB-nt therefore was introduced and realized at the chair of General Materials Properties of the University Erlangen-Nuremberg. Cast Astra alloys are like other nickel-base superalloys morphologically very inhomogeneous and affected by segregation. In the interdendritic region different structures with huge γ' precipitates are formed. These inhomogeneities and remaining eutectics degrade the mechanical properties, witch makes an understanding of the subsiding processes at solidification of residual melt important for the casting process and the heat treatment. This is why the last stage solidification in the interdendritic region was analyzed. With the help of focused ion beam nanotomography, three different structures identified from 2-D sections could be assigned to one original 3-D structure. It was pointed out, that only the orientation of the plane of the 2-D cut influences the appearance in the 2-D section. The tomography information was used to explain the development during solidification and to create a model of last stage solidification. The interdendritic region is solidifying under the development of eutectic islands. The structure nucleates eutectically epitaxially at primary dendrite arms, with formation of fine γ/γ' precipitates. During solidification the γ' precipitates coarsen in a rod-like structure, and end up in large γ' precipitates. Simulations and other investigations could approve this model. First three

  19. Controlled fabrication of nanopores using a direct focused ion beam approach with back face particle detection.

    Science.gov (United States)

    Patterson, N; Adams, D P; Hodges, V C; Vasile, M J; Michael, J R; Kotula, P G

    2008-06-11

    We report a direct, ion drilling technique that enables the reproducible fabrication and placement of nanopores in membranes of different thickness. Using a 30 keV focused Ga ion beam column combined with an in situ, back face, multi-channelplate particle detector, nanopores are sputtered in Si(3)N(4) and W/Si(3)N(4) to have diameters as small as 12 nm. Transmission electron microscopy shows that focused ion beam-drilled holes are near-conical with the diameter decreasing from entry to exit side. By monitoring the detector signal during ion exposure, the drilled hole width can be minimized such that the exit-side diameter is smaller than the full width at half-maximum of the nominally Gaussian-shaped incident beam. Judicious choice of the beam defining aperture combined with back face particle detection allows for reproducible exit-side hole diameters between 18 and 100 nm. The nanopore direct drilling technique does not require potentially damaging broad area exposure to tailor hole sizes. Moreover, this technique successfully achieves breakthrough despite the effects of varying membrane thickness, redeposition, polycrystalline grain structure, and slight ion beam current fluctuations.

  20. Generation and focusing of electron beams with initial transverse-longitudinal correlation

    Energy Technology Data Exchange (ETDEWEB)

    Harris, J. R. [Colorado State Univ., Fort Collins, CO (United States) Dept. of Electrical and Computer Engineering.; Lewellen, J. W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Poole, B. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-10-07

    In charged particle beams, one of the roles played by space charge is to couple the transverse and longitudinal dynamics of the beam. This can lead to very complex phenomena which are generally studied using computer simulations. However, in some cases models based on phenomenological or analytic approximations can provide valuable insight into the system behavior. In this paper, we employ such approximations to investigate the conditions under which all the slices of a space charge dominated electron beam with slowly varying current could be focused to a waist with the same radius and at the same location, independent of slice current, and show that this can be accomplished approximately if the initial transverse-longitudinal correlation introduced onto the beam by the electron gun is chosen to compensate for the transverse-longitudinal correlation introduced onto the beam in the drift section. The validity of our approximations is assessed by use of progressively more realistic calculations. We also consider several design elements of electron guns that affect the initial correlations in the beams they generate.

  1. The theory and simulation of relativistic electron beam transport in the ion-focused regime

    International Nuclear Information System (INIS)

    Swanekamp, S.B.; Holloway, J.P.; Kammash, T.; Gilgenbach, R.M.

    1992-01-01

    Several recent experiments involving relativistic electron beam (REB) transport in plasma channels show two density regimes for efficient transport; a low-density regime known as the ion-focused regime (IFR) and a high-pressure regime. The results obtained in this paper use three separate models to explain the dependency of REB transport efficiency on the plasma density in the IFR. Conditions for efficient beam transport are determined by examining equilibrium solutions of the Vlasov--Maxwell equations under conditions relevant to IFR transport. The dynamic force balance required for efficient IFR transport is studied using the particle-in-cell (PIC) method. These simulations provide new insight into the transient beam front physics as well as the dynamic approach to IFR equilibrium. Nonlinear solutions to the beam envelope are constructed to explain oscillations in the beam envelope observed in the PIC simulations but not contained in the Vlasov equilibrium analysis. A test particle analysis is also developed as a method to visualize equilibrium solutions of the Vlasov equation. This not only provides further insight into the transport mechanism but also illustrates the connections between the three theories used to describe IFR transport. Separately these models provide valuable information about transverse beam confinement; together they provide a clear physical understanding of REB transport in the IFR

  2. THERMAL SHOCK ANALYSIS OF WINDOWS INTERACTING WITH ENERGETIC, FOCUSED BEAM OF THE BNL MUON TARGET EXPERIMENT

    International Nuclear Information System (INIS)

    SIMOS, N.; KIRK, H.; PRIGL, R.; BROWN, K.; MCDONALD, K.

    2001-01-01

    In this paper, issues associated with the interaction of a proton beam with windows designed for the muon targetry experiment E951 at BNL are explored. Specifically, a 24 GeV proton beam up to 16 TP per pulse and a pulse length of 100 ns is tightly focused (to 0.5 mm rms radius) on an experimental target. The need to maintain an enclosed environment around the target implies the use of beam windows that will survive the passage of the proton beam. The required beam parameters in such a setting will induce very high thermal, quasi-static and shock stresses in the window structure that exceed the strength of most common materials. In this effort, a detailed analysis of the thermal/shock response of beam windows is attempted through a transient thermal and stress wave propagation formulation that incorporates energy deposition rates calculated the by hadron interaction code MARS. The thermal response of the window structure and the subsequent stress wave generation and propagation are computed using the finite element analysis procedures of the ANSYS code. This analysis attempts to address issues pertaining to an optimal combination of material, window thickness and pulse structure that will allow for a window to safely survive the extreme demands of the experiment

  3. An angled nano-tunnel fabricated on poly(methyl methacrylate) by a focused ion beam

    International Nuclear Information System (INIS)

    Her, Eun Kyu; Chung, Hee-Suk; Oh, Kyu Hwan; Moon, Myoung-Woon

    2009-01-01

    Angled nano-scale tunnels with high aspect ratio were fabricated on poly(methyl methacrylate) (PMMA) using a focused ion beam (FIB). The fabrication parameters such as ion fluence, incidence angle, and acceleration voltage of the Ga + ion beam were first studied on the PMMA surface to explore the formation of the nano-scale configurations such as nano-holes and cones with diameter in the range of 50-150 nm at an ion beam acceleration voltage of 5-20 kV. It was also found that the PMMA surface exposed to FIB was changed into an amorphous graphitic structure. Angled nano-scale tunnels were fabricated with high aspect ratio of 700-1500 nm in depth and 60 nm in mean diameter at an ion beam acceleration voltage of 5 kV and under a specific ion beam current. The angle of the nano-tunnels was found to follow the incident angle of the ion beam tilted from 0 0 to 85 0 , which has the potential for creating a mold for anisotropic adhesives by mimicking the hairs on a gecko's feet.

  4. In situ micro-focused X-ray beam characterization with a lensless camera using a hybrid pixel detector

    International Nuclear Information System (INIS)

    Kachatkou, Anton; Marchal, Julien; Silfhout, Roelof van

    2014-01-01

    Position and size measurements of a micro-focused X-ray beam, using an X-ray beam imaging device based on a lensless camera that collects radiation scattered from a thin foil placed in the path of the beam at an oblique angle, are reported. Results of studies on micro-focused X-ray beam diagnostics using an X-ray beam imaging (XBI) instrument based on the idea of recording radiation scattered from a thin foil of a low-Z material with a lensless camera are reported. The XBI instrument captures magnified images of the scattering region within the foil as illuminated by the incident beam. These images contain information about beam size, beam position and beam intensity that is extracted during dedicated signal processing steps. In this work the use of the device with beams for which the beam size is significantly smaller than that of a single detector pixel is explored. The performance of the XBI device equipped with a state-of-the-art hybrid pixel X-ray imaging sensor is analysed. Compared with traditional methods such as slit edge or wire scanners, the XBI micro-focused beam characterization is significantly faster and does not interfere with on-going experiments. The challenges associated with measuring micrometre-sized beams are described and ways of optimizing the resolution of beam position and size measurements of the XBI instrument are discussed

  5. Calculation of the illuminance distribution in the focal spot of a focusing system taking into account aberrations in this system and divergence of a focused laser beam

    International Nuclear Information System (INIS)

    Gitin, Andrey V

    2007-01-01

    The dependence of the focal-spot size of a 'deep' parabolic mirror reflector on the laser-beam divergence is analysed by the method of elementary reflections. The dependence of the focal-beam diameter of an ideal focusing optical system on the laser-beam parameters is described. The expression is obtained for calculating the illumination distribution in the focal spot of a 'deep' mirror reflector which takes into account both aberrations and light-gathering power of the reflector and the divergence of a focused laser beam. (optical systems)

  6. Production of tightly focused E-beam with high-current accelerators

    International Nuclear Information System (INIS)

    Poukey, J.W.; Mazarakis, M.G.; Frost, C.A.; Ramirez, J.J.

    1991-01-01

    Using numerical modeling the authors study several approaches to the problem of designing an injector to produce a 3-30 kA, 2-4 mm diameter electron beam in the energy range 10-20 MeV. The cathode may be small in diameter and immersed in a strong magnetic field, producing an equilibrium beam for transport to a target (the immersed case). This approach appears to be the most promising for applications such as radiography, and the authors shall emphasize it in this paper. The alternative is the conventional non-immersed cathode, in which the beam from a larger-radius, cold-beam cathode is focused with magnetic lenses to a small spot on the target. Because the non-immersed cathode, in which the beam from a larger-radius, cold-beam cathode is focused with a magnetic lenses to a small spot on the target. Because the non-immersed case has been extensively studied, and because it has advantages for these purposes, the authors shall only discuss a few of the non-immersed-cathode injector studies, primarily for purposes of comparison. Either type of diode is to be powered by an inductive voltage adder based on the successful SABRE/Hermes III/RADLAC (SMILE) magnetically-insulated-transmission-line design concepts. A possible variation uses a re-entrant geometry with low electric stresses so that only the cathode face emits. The authors discuss issues such as dumping excess current and voltage dependence of the focus

  7. Fabrication of photonic crystals on several kinds of semiconductor materials by using focused-ion beam method

    International Nuclear Information System (INIS)

    Xu Xingsheng; Chen Hongda; Xiong Zhigang; Jin Aizi; Gu Changzhi; Cheng Bingying; Zhang Daozhong

    2007-01-01

    In this paper, we introduced the fabrication of photonic crystals on several kinds of semiconductor materials by using focused-ion beam machine, it shows that the method of focused-ion beam can fabricate two-dimensional photonic crystal and photonic crystal device efficiently, and the quality of the fabricated photonic crystal is high. Using the focused-ion beam method, we fabricate photonic crystal wavelength division multiplexer, and its characteristics are analyzed

  8. Titanium dioxide fine structures by RF magnetron sputter method deposited on an electron-beam resist mask

    Science.gov (United States)

    Hashiba, Hideomi; Miyazaki, Yuta; Matsushita, Sachiko

    2013-09-01

    Titanium dioxide (TiO2) has been draw attention for wide range of applications from photonic crystals for visible light range by its catalytic characteristics to tera-hertz range by its high refractive index. We present an experimental study of fabrication of fine structures of TiO2 with a ZEP electron beam resist mask followed by Ti sputter deposition techniques. A TiO2 thin layer of 150 nm thick was grown on an FTO glass substrate with a fine patterned ZEP resist mask by a conventional RF magnetron sputter method with Ti target. The deposition was carried out with argon-oxygen gases at a pressure of 5.0 x 10 -1 Pa in a chamber. During the deposition, ratio of Ar-O2 gas was kept to the ratio of 2:1 and the deposition ratio was around 0.5 Å/s to ensure enough oxygen to form TiO2 and low temperature to avoid deformation of fine pattern of the ZPU resist mask. Deposited TiO2 layers are white-transparent, amorphous, and those roughnesses are around 7 nm. Fabricated TiO2 PCs have wider TiO2 slabs of 112 nm width leaving periodic 410 x 410 nm2 air gaps. We also studied transformation of TiO2 layers and TiO2 fine structures by baking at 500 °C. XRD measurement for TiO2 shows that the amorphous TiO2 transforms to rutile and anatase forms by the baking while keeping the same profile of the fine structures. Our fabrication method can be one of a promising technique to optic devices on researches and industrial area.

  9. Coordinate transformation based cryo-correlative methods for electron tomography and focused ion beam milling

    International Nuclear Information System (INIS)

    Fukuda, Yoshiyuki; Schrod, Nikolas; Schaffer, Miroslava; Feng, Li Rebekah; Baumeister, Wolfgang; Lucic, Vladan

    2014-01-01

    Correlative microscopy allows imaging of the same feature over multiple length scales, combining light microscopy with high resolution information provided by electron microscopy. We demonstrate two procedures for coordinate transformation based correlative microscopy of vitrified biological samples applicable to different imaging modes. The first procedure aims at navigating cryo-electron tomography to cellular regions identified by fluorescent labels. The second procedure, allowing navigation of focused ion beam milling to fluorescently labeled molecules, is based on the introduction of an intermediate scanning electron microscopy imaging step to overcome the large difference between cryo-light microscopy and focused ion beam imaging modes. These methods make it possible to image fluorescently labeled macromolecular complexes in their natural environments by cryo-electron tomography, while minimizing exposure to the electron beam during the search for features of interest. - Highlights: • Correlative light microscopy and focused ion beam milling of vitrified samples. • Coordinate transformation based cryo-correlative method. • Improved correlative light microscopy and cryo-electron tomography

  10. Exploring a new strategy for nanofabrication: deposition by scattered Ga ions using focused ion beam.

    Science.gov (United States)

    Tripathi, Sarvesh K; Shukla, Neeraj; Kulkarni, Vishwas N

    2009-02-18

    We report a new strategy of nanofabrication using the focused ion beam (FIB)-based chemical vapor deposition method. It utilizes scattered Ga ions to decompose organometallic molecules of the precursor gas for depositing the metallic element on a surface with the advantage of producing uniform metallic coats on those surfaces of nanostructures which are not directly accessible to the primary beam. The method can be used to provide electrical contacts on inaccessible regions of prototype nanodevices, such as ion batteries, electrophoresis cells, cantilevers, etc, which have been demonstrated and explained by depositing Pt and W on different surfaces of 3D nanostructures.

  11. Laser-cooled atoms as a focused ion-beam source

    International Nuclear Information System (INIS)

    Hanssen, J. L.; McClelland, J. J.; Dakin, E. A.; Jacka, M.

    2006-01-01

    The evolving field of nanofabrication demands that more precise fabrication and evaluation tools be developed. We describe a method for creating a high quality focused ion beam with enhanced capabilities using an ion source based on laser-cooled neutral atoms in a magneto-optical trap. This technique will improve resolution and brightness beyond the current state of the art, can be used with the full range of atomic species that can be laser cooled and trapped, and will allow unprecedented control over the ion emission, allowing, for example, the production of single ions ''on demand.'' We give estimates for the emittance and present a realistic ray tracing analysis of a basic focusing system demonstrating the feasibility of focusing the beam to a spot size of less than 10 nm

  12. On production and asymmetric focusing of flat electron beams using rectangular capillary discharge plasmas

    Science.gov (United States)

    Bagdasarov, G. A.; Bobrova, N. A.; Boldarev, A. S.; Olkhovskaya, O. G.; Sasorov, P. V.; Gasilov, V. A.; Barber, S. K.; Bulanov, S. S.; Gonsalves, A. J.; Schroeder, C. B.; van Tilborg, J.; Esarey, E.; Leemans, W. P.; Levato, T.; Margarone, D.; Korn, G.; Kando, M.; Bulanov, S. V.

    2017-12-01

    A method for the asymmetric focusing of electron bunches, based on the active plasma lensing technique, is proposed. This method takes advantage of the strong inhomogeneous magnetic field generated inside the capillary discharge plasma to focus on the ultrarelativistic electrons. The plasma and magnetic field parameters inside the capillary discharge are described theoretically and modeled with dissipative magnetohydrodynamic computer simulations enabling analysis of the capillaries of rectangle cross-sections. Large aspect ratio rectangular capillaries might be used to transport electron beams with high emittance asymmetries, as well as assist in forming spatially flat electron bunches for final focusing before the interaction point.

  13. Envelope model for passive magnetic focusing of an intense proton or ion beam propagating through thin foils

    Directory of Open Access Journals (Sweden)

    Steven M. Lund

    2013-04-01

    Full Text Available Ion beams (including protons with low emittance and high space-charge intensity can be propagated with normal incidence through a sequence of thin metallic foils separated by vacuum gaps of order the characteristic transverse beam extent to transport/collimate the beam or to focus it to a small transverse spot. Energetic ions have sufficient range to pass through a significant number of thin foils with little energy loss or scattering. The foils reduce the (defocusing radial electric self-field of the beam while not altering the (focusing azimuthal magnetic self-field of the beam, thereby allowing passive self-beam focusing if the magnetic field is sufficiently strong relative to the residual electric field. Here we present an envelope model developed to predict the strength of this passive (beam generated focusing effect under a number of simplifying assumptions including relatively long pulse duration. The envelope model provides a simple criterion for the necessary foil spacing for net focusing and clearly illustrates system focusing properties for either beam collimation (such as injecting a laser-produced proton beam into an accelerator or for magnetic pinch focusing to a small transverse spot (for beam driven heating of materials. An illustrative example is worked for an idealization of a recently performed laser-produced proton-beam experiment to provide guidance on possible beam focusing and collimation systems. It is found that foils spaced on the order of the characteristic transverse beam size desired can be employed and that envelope divergence of the initial beam entering the foil lens must be suppressed to limit the total number of foils required to practical values for pinch focusing. Relatively modest proton-beam current at 10 MeV kinetic energy can clearly demonstrate strong magnetic pinch focusing achieving a transverse rms extent similar to the foil spacing (20–50  μm gaps in beam propagation distances of tens of mm

  14. Beam dynamics in the final focus section of the future linear collider

    CERN Document Server

    AUTHOR|(SzGeCERN)739431; TOMAS, Rogelio

    The exploration of new physics in the ``Tera electron-Volt''~(TeV) scale with precision measurements requires lepton colliders providing high luminosities to obtain enough statistics for the particle interaction analysis. In order to achieve design luminosity values, linear colliders feature nanometer beam spot sizes at the Interaction~Point~(IP).\\par In addition to several effects affecting the luminosity, three main issues to achieve the beam size demagnification in the Final Focus Section (FFS) of the accelerator are the chromaticity correction, the synchrotron radiation effects and the correction of the lattice errors.\\par This thesis considers two important aspects for linear colliders: push the limits of linear colliders design, in particular the chromaticity correction and the radiation effects at 3~TeV, and the instrumentation and experimental work on beam stabilization in a test facility.\\par The current linear collider projects, CLIC~\\cite{CLICdes} and ILC~\\cite{ILCdes}, have lattices designed using...

  15. Phase-transition oscillations induced by a strongly focused laser beam.

    Science.gov (United States)

    Devailly, Clémence; Crauste-Thibierge, Caroline; Petrosyan, Artyom; Ciliberto, Sergio

    2015-11-01

    We report the observation of a surprising phenomenon consisting in a oscillating phase transition which appears in a binary mixture when this is enlightened by a strongly focused infrared laser beam. The mixture is poly-methyl-meth-acrylate (PMMA)-3-octanone, which has an upper critical solution temperature at T(c)=306.6K and volume fraction ϕ(c)=12.8% [Crauste et al., arXiv:1310.6720, 2013]. We describe the dynamical properties of the oscillations, which are produced by a competition between various effects: the local accumulation of PMMA produced by the laser beam, thermophoresis, and nonlinear diffusion. We show that the main properties of this kind of oscillations can be reproduced in the Landau theory for a binary mixture in which a local driving mechanism, simulating the laser beam, is introduced.

  16. Spectral study of the electron beam emitted from a 3 kJ plasma focus

    International Nuclear Information System (INIS)

    Patran, A; Tan, L C; Stoenescu, D; Rafique, M S; Rawat, R S; Springham, S V; Tan, T L; Lee, P; Zakaullah, M; Lee, S

    2005-01-01

    In a 3 kJ Mather-type plasma focus device operated in neon, the electron beam emission is investigated using both a magnetic electron energy analyser (in the 30-660 keV range) and a Rogowski coil (coupled with an appropriate RC passive integrator). Several electron emission features are identified and correlated with the x-ray emission in different energy ranges. The electron beam output shows very strong correlation with the general plasma dynamics (breakdown, axial and radial acceleration, pinch and post-pinch phases). The electrons' energy spectra showed most of the electron emission concentrating below 200 keV and negligible emission with energy above 350 keV. At 4 mbar neon, the electron emission, as well as the beam energy, is the highest and has a good shot-to-shot reproducibility

  17. Spot size, depth-of-focus, and diffraction ring intensity formulas for truncated Gaussian beams.

    Science.gov (United States)

    Urey, Hakan

    2004-01-20

    Simple polynomial formulas to calculate the FWHM and full width at 1/e2 intensity diffraction spot size and the depth of focus at a Strehl ratio of 0.8 and 0.5 as a function of a Gaussian beam truncation ratio and a system f-number are presented. Formulas are obtained by use of the numerical integration of a Huygens-Fresnel diffraction integral and can be used to calculate the number of resolvable spots, the modulation transfer function, and the defocus tolerance of optical systems that employ laser beams. I also derived analytical formulas for the diffraction ring intensity as a function of the Gaussian beam truncation ratio and the system f-number. Such formulas can be used to estimate the diffraction-limited contrast of display and imaging systems.

  18. Supersonic Fe beam source for chromatic aberration-free laser focusing of atoms

    CERN Document Server

    Bosch, R C M; Van der Straten, P; Leeuwen, K A H

    2002-01-01

    A monochromatic Fe beam is generated by heated supersonic expansion of argon seeded with Fe vapor. At a nozzle temperature of 1930 K and 800 torr argon inlet pressure the Fe beam has an axial velocity spread of 8% and intensity of 3 x 10 sup 1 sup 5 s sup - sup 1 sr sup - sup 1 , corresponding to a deposition rate of 10 nm/h at 150 mm from the nozzle. The two-chamber alumina crucibles are chemically stable for liquid Fe. With 400 mm sup 3 Fe we have operated for more than 200 hours without reloading. The power consumption at 1930 K is 750 W. Temperature stability at constant power (without feedback) is better than 30 K. The source is intended for deposition of nano-structures by laser focusing of the Fe beam. The small axial velocity spread virtually eliminates the increase in focal spot size due to chromatic aberration. (authors)

  19. Comparison of technologies for nano device prototyping with a special focus on ion beams: A review

    Science.gov (United States)

    Bruchhaus, L.; Mazarov, P.; Bischoff, L.; Gierak, J.; Wieck, A. D.; Hövel, H.

    2017-03-01

    Nano device prototyping (NDP) is essential for realizing and assessing ideas as well as theories in the form of nano devices, before they can be made available in or as commercial products. In this review, application results patterned similarly to those in the semiconductor industry (for cell phone, computer processors, or memory) will be presented. For NDP, some requirements are different: thus, other technologies are employed. Currently, in NDP, for many applications direct write Gaussian vector scan electron beam lithography (EBL) is used to define the required features in organic resists on this scale. We will take a look at many application results carried out by EBL, self-organized 3D epitaxy, atomic probe microscopy (scanning tunneling microscope/atomic force microscope), and in more detail ion beam techniques. For ion beam techniques, there is a special focus on those based upon liquid metal (alloy) ion sources, as recent developments have significantly increased their applicability for NDP.

  20. Superposition of nonparaxial vectorial complex-source spherically focused beams: Axial Poynting singularity and reverse propagation

    Science.gov (United States)

    Mitri, F. G.

    2016-08-01

    In this work, counterintuitive effects such as the generation of an axial (i.e., long the direction of wave motion) zero-energy flux density (i.e., axial Poynting singularity) and reverse (i.e., negative) propagation of nonparaxial quasi-Gaussian electromagnetic (EM) beams are examined. Generalized analytical expressions for the EM field's components of a coherent superposition of two high-order quasi-Gaussian vortex beams of opposite handedness and different amplitudes are derived based on the complex-source-point method, stemming from Maxwell's vector equations and the Lorenz gauge condition. The general solutions exhibiting unusual effects satisfy the Helmholtz and Maxwell's equations. The EM beam components are characterized by nonzero integer degree and order (n ,m ) , respectively, an arbitrary waist w0, a diffraction convergence length known as the Rayleigh range zR, and a weighting (real) factor 0 ≤α ≤1 that describes the transition of the beam from a purely vortex (α =0 ) to a nonvortex (α =1 ) type. An attractive feature for this superposition is the description of strongly focused (or strongly divergent) wave fields. Computations of the EM power density as well as the linear and angular momentum density fluxes illustrate the analysis with particular emphasis on the polarization states of the vector potentials forming the beams and the weight of the coherent beam superposition causing the transition from the vortex to the nonvortex type. Should some conditions determined by the polarization state of the vector potentials and the beam parameters be met, an axial zero-energy flux density is predicted in addition to a negative retrograde propagation effect. Moreover, rotation reversal of the angular momentum flux density with respect to the beam handedness is anticipated, suggesting the possible generation of negative (left-handed) torques. The results are particularly useful in applications involving the design of strongly focused optical laser

  1. Source-to-target simulation of simultaneous longitudinal and transverse focusing of heavy ion beams

    Directory of Open Access Journals (Sweden)

    D. R. Welch

    2008-06-01

    Full Text Available Longitudinal bunching factors in excess of 70 of a 300-keV, 27-mA K^{+} ion beam have been demonstrated in the neutralized drift compression experiment [P. K. Roy et al., Phys. Rev. Lett. 95, 234801 (2005PRLTAO0031-900710.1103/PhysRevLett.95.234801] in rough agreement with particle-in-cell source-to-target simulations. A key aspect of these experiments is that a preformed plasma provides charge neutralization of the ion beam in the last one meter drift region where the beam perveance becomes large. The simulations utilize the measured ion source temperature, diode voltage, and induction-bunching-module voltage waveforms in order to determine the initial beam longitudinal phase space which is critical to accurate modeling of the longitudinal compression. To enable simultaneous longitudinal and transverse compression, numerical simulations were used in the design of the solenoidal focusing system that compensated for the impact of the applied velocity tilt on the transverse phase space of the beam. Complete source-to-target simulations, that include detailed modeling of the diode, magnetic transport, induction bunching module, and plasma neutralized transport, were critical to understanding the interplay between the various accelerator components in the experiment. Here, we compare simulation results with the experiment and discuss the contributions to longitudinal and transverse emittance that limit the final compression.

  2. Multi-beamlet focusing of intense negative ion beams by aperture displacement technique

    Energy Technology Data Exchange (ETDEWEB)

    Takeiri, Y.; Kaneko, O.; Oka, Y.; Tsumori, K.; Asano, E.; Akiyama, R.; Kawamoto, T.; Kuroda, T.; Ando, A.

    1995-08-01

    Multi-beamlet focusing of an intense negative ion beam has been performed using the beamlet steering by the aperture displacement. The apertures of the grounded grid were displaced as all beamlets of 270 (18 x 15) in the area of 25 cm x 26 cm would be steered to a common point (a focal point) in both the two-stage and the single-stage accelerators. The multi-beamlets were successfully focused and the e-folding half width of 10 cm was achieved 11.2 m downstream from the ion source in both the accelerators. The corresponding gross divergence angle is 9 mrad. The negative ion beamlets are deflected by the magnetic field for the electron deflection at the extraction grid and the deflection direction oppositely changes line by line, resulting in the beam split in the deflection direction. This beamlet deflection was well compensated also using the beamlet steering by the aperture displacement of the grounded grid. The beam acceleration properties related with the beam divergence and the H{sup -} ion current were nearly the same for both the two-stage and the single-stage accelerators, and were dependent on the ratio of the extraction to the acceleration electric fields. (author).

  3. Improved Light Extraction Efficiency by Photonic Crystal Arrays on Transparent Contact Layer Using Focused Ion Beams

    International Nuclear Information System (INIS)

    Wu, G.M.; Tsai, B.H.; Kung, S.F.; Wu, C.F.

    2011-01-01

    Nitride-based thin-film materials have become increasingly important for the high brightness light-emitting diode applications. The improvements in light extraction and lower power consumption are highly desired. Although the internal quantum efficiency of GaN-based LED has been relatively high, only a small fraction of light can be extracted. In this study, a new design of two-dimensional photonic crystal array has been prepared on the top transparent contact layer of indium-tin oxide film to improve the light extraction efficiency using focused ion beam. The acceleration voltage of the Ga dual-beam nanotechnology system SMI 3050 was 30 kV and the ion beam current was 100 pA. The cylindrical air holes had the diameter of 150 nm and depth of 100 nm. The micro photoluminescence analysis results showed that the light output intensity could be 1.5 times of that of the non-patterned control sample. In addition, the structural damage from the focused ion beam drilling of GaN step could be eliminated. The excellent I-V characteristics have been maintained, and the external light extraction efficiency would be still improved for the LED devices. (author)

  4. Ion beam focusing by the atomic chains of a crystal lattice

    International Nuclear Information System (INIS)

    Shulga, V.I.

    1975-01-01

    A study is made of the focusing of a parallel ion beam by a pair of close packed atomic chains of a crystal. The focal length of this system has been calculated to the approximation of continuous potential of chain in the general form and also for a number of specific potentials of ion-atom interactions. Ar ion beam focusing by a Cu chain pair is discusssed in detail. For this case, the focal length has been calculated as a function of ion energy using the method of computer simulation of ion trajectories in the chain field. The calculations were made on the basis of the Born-Mayer potential with various constants. A pronounced dependence of focal length on the constant in this potential has been found. (author)

  5. Selective filling of photonic crystal fibers using focused ion beam milled microchannels

    DEFF Research Database (Denmark)

    Wang, Fei; Yuan, Scott Wu; Hansen, Ole

    2011-01-01

    We introduce a versatile, robust, and integrated technique to selectively fill fluid into a desired pattern of air holes in a photonic crystal fiber (PCF). Focused ion beam (FIB) is used to efficiently mill a microchannel on the end facet of a PCF before it is spliced to a single-mode fiber (SMF)......). Selected air holes are therefore exposed to the atmosphere through the microchannel for fluid filling. A low-loss in-line tunable optical hybrid fiber device is demonstrated by using such a technique. (C) 2011 Optical Society of America......We introduce a versatile, robust, and integrated technique to selectively fill fluid into a desired pattern of air holes in a photonic crystal fiber (PCF). Focused ion beam (FIB) is used to efficiently mill a microchannel on the end facet of a PCF before it is spliced to a single-mode fiber (SMF...

  6. The freely localized microwave discharge in air in the focused beam of the electromagnetic energy

    International Nuclear Information System (INIS)

    Alexandrov, A.F.; Kuzovnikov, A.A.; Shibkov, V.M.

    1995-01-01

    The successfull use of the microwave discharge in many applications make it necessary to research the physics of a new kind of discharge - the electrodeless microwave discharge in the focused beam, in the free space and to search for ways to optimize this discharge parameters. The breakdown was performed in a discharge chamber at approximately free space conditions: R/λ much-gt 1, where R = 1 m is the discharge chamber's dimension, λ = 2 divided-by 10 cm is the wavelength of the microwave radiation. The focused electromagnetic beam was formed by a trumped-lens antenna. The electric field E≤6 kV/cm, the density of energy flow S≤10 5 W/cm 2 , the wave is linearity polarized. The microwave pulse duration could be changed from 1 μs to 1 ms. The gas pressure (nitrogen, air) is varied from 1 to 760 torr

  7. Single Bunch Electron Cloud Effects in the NLC Beam Delivery System(LCC-0126)

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D

    2003-12-08

    A positron beam passing through a linear collider beam delivery beam line is finely focused to desired specifications during collimation and especially in Final Focusing (FFS). Undesired additional focusing is generated by beam-electron cloud interactions, which typically leads to beam size increases at high cloud densities. This paper examines the severity of the electron cloud effects and assesses the critical cloud density.

  8. Focused-ion beam patterning of organolead trihalide perovskite for subwavelength grating nanophotonic applications

    KAUST Repository

    Alias, Mohd Sharizal

    2015-07-30

    The coherent amplified spontaneous emission and high photoluminescence quantum efficiency of organolead trihalide perovskite have led to research interest in this material for use in photonic devices. In this paper, the authors present a focused-ion beam patterning strategy for methylammonium lead tribromide (MAPbBr3) perovskite crystal for subwavelength grating nanophotonic applications. The essential parameters for milling, such as the number of scan passes, dwell time, ion dose, ion current, ion incident angle, and gas-assisted etching, were experimentally evaluated to determine the sputtering yield of the perovskite. Based on our patterning conditions, the authors observed that the sputtering yield ranged from 0.0302 to 0.0719 μm3/pC for the MAPbBr3 perovskite crystal. Using XeF2 for the focused-ion beam gas-assisted etching, the authors determined that the etching rate was reduced to between 0.40 and 0.97, depending on the ion dose, compared with milling with ions only. Using the optimized patterning parameters, the authors patterned binary and circular subwavelength grating reflectors on the MAPbBr3 perovskite crystal using the focused-ion beam technique. Based on the computed grating structure with around 97% reflectivity, all of the grating dimensions (period, duty cycle, and grating thickness) were patterned with nanoscale precision (>±3 nm), high contrast, and excellent uniformity. Our results provide a platform for utilizing the focused-ion beam technique for fast prototyping of photonic nanostructures or nanodevices on organolead trihalide perovskite.

  9. Nano-fabrication of diffractive optics for soft X-ray and atom beam focusing

    International Nuclear Information System (INIS)

    Rehbein, S.

    2002-01-01

    Nano-structuring processes are described for manufacturing diffractive optics for the condenser-monochromator set-up of the transmission X-ray microscope (TXM) and for the scanning transmission X-ray microscope (STXM) at the BESSY II electron storage ring in Berlin. Furthermore, a process for manufacturing free-standing nickel zone plates for helium atom beam focusing experiments is presented. (author)

  10. Combined centroid-envelope dynamics of intense, magnetically focused charged beams surrounded by conducting walls

    International Nuclear Information System (INIS)

    Fiuza, K.; Rizzato, F.B.; Pakter, R.

    2006-01-01

    In this paper we analyze the combined envelope-centroid dynamics of magnetically focused high-intensity charged beams surrounded by conducting walls. Similar to the case where conducting walls are absent, it is shown that the envelope and centroid dynamics decouple from each other. Mismatched envelopes still decay into equilibrium with simultaneous emittance growth, but the centroid keeps oscillating with no appreciable energy loss. Some estimates are performed to analytically obtain characteristics of halo formation seen in the full simulations

  11. Using an energized oxygen micro-jet for improved graphene etching by focused electron beam

    International Nuclear Information System (INIS)

    Kim, Songkil; Henry, Mathias; Fedorov, Andrei G.

    2015-01-01

    We report on an improved Focused Electron Beam Induced Etching (FEBIE) process, which exploits heated oxygen delivery via a continuous supersonic micro-jet resulting in faster graphene patterning and better etch feature definition. Positioning a micro-jet in close proximity to a graphene surface with minimal jet spreading due to a continuous regime of gas flow at the exit of the 10 μm inner diameter capillary allows for focused exposure of the surface to reactive oxygen at high mass flux and impingement energy of a supersonic gas stream localized to a small etching area exposed to electron beam. These unique benefits of focused supersonic oxygen delivery to the surface enable a dramatic increase in the etch rate of graphene with no parasitic carbon “halo” deposition due to secondary electrons from backscattered electrons (BSE) in the area surrounding the etched regions. Increase of jet temperature via local nozzle heating provides means for enhancing kinetic energy of impinging oxygen molecules, which further speed up the etch, thus minimizing the beam exposure time and required electron dose, before parasitic carbon film deposition due to BSE mediated decomposition of adsorbed hydrocarbon contaminants has a measurable impact on quality of graphene etched features. Interplay of different physical mechanisms underlying an oxygen micro-jet assisted FEBIE process is discussed with support from experimental observations

  12. Using an energized oxygen micro-jet for improved graphene etching by focused electron beam

    Science.gov (United States)

    Kim, Songkil; Henry, Mathias; Fedorov, Andrei G.

    2015-12-01

    We report on an improved Focused Electron Beam Induced Etching (FEBIE) process, which exploits heated oxygen delivery via a continuous supersonic micro-jet resulting in faster graphene patterning and better etch feature definition. Positioning a micro-jet in close proximity to a graphene surface with minimal jet spreading due to a continuous regime of gas flow at the exit of the 10 μm inner diameter capillary allows for focused exposure of the surface to reactive oxygen at high mass flux and impingement energy of a supersonic gas stream localized to a small etching area exposed to electron beam. These unique benefits of focused supersonic oxygen delivery to the surface enable a dramatic increase in the etch rate of graphene with no parasitic carbon "halo" deposition due to secondary electrons from backscattered electrons (BSE) in the area surrounding the etched regions. Increase of jet temperature via local nozzle heating provides means for enhancing kinetic energy of impinging oxygen molecules, which further speed up the etch, thus minimizing the beam exposure time and required electron dose, before parasitic carbon film deposition due to BSE mediated decomposition of adsorbed hydrocarbon contaminants has a measurable impact on quality of graphene etched features. Interplay of different physical mechanisms underlying an oxygen micro-jet assisted FEBIE process is discussed with support from experimental observations.

  13. Applied Focused Ion Beam Techniques for Sample Preparation of Astromaterials for Integrated Nano-Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Graham, G A; Teslich, N E; Kearsley, A T; Stadermann, F J; Stroud, R M; Dai, Z R; Ishii, H A; Hutcheon, I D; Bajt, S; Snead, C J; Weber, P K; Bradley, J P

    2007-02-20

    Sample preparation is always a critical step in study of micrometer sized astromaterials available for study in the laboratory, whether their subsequent analysis is by electron microscopy or secondary ion mass spectrometry. A focused beam of gallium ions has been used to prepare electron transparent sections from an interplanetary dust particle, as part of an integrated analysis protocol to maximize the mineralogical, elemental, isotopic and spectroscopic information extracted from one individual particle. In addition, focused ion beam techniques have been employed to extract cometary residue preserved on the rims and walls of micro-craters in 1100 series aluminum foils that were wrapped around the sample tray assembly on the Stardust cometary sample collector. Non-ideal surface geometries and inconveniently located regions of interest required creative solutions. These include support pillar construction and relocation of a significant portion of sample to access a region of interest. Serial sectioning, in a manner similar to ultramicrotomy, is a significant development and further demonstrates the unique capabilities of focused ion beam microscopy for sample preparation of astromaterials.

  14. Correlative Raman spectroscopy and focused ion beam for targeted phase boundary analysis of titania polymorphs

    Energy Technology Data Exchange (ETDEWEB)

    Mangum, John S.; Chan, Lisa H.; Schmidt, Ute; Garten, Lauren M.; Ginley, David S.; Gorman, Brian P.

    2018-05-01

    Site-specific preparation of specimens using focused ion beam instruments for transmission electron microscopy is at the forefront of targeting regions of interest for nanoscale characterization. Typical methods of pinpointing desired features include electron backscatter diffraction for differentiating crystal structures and energy-dispersive X-Ray spectroscopy for probing compositional variations. Yet there are situations, notably in the titanium dioxide system, where these techniques can fail. Differentiating between the brookite and anatase polymorphs of titania is either excessively laborious or impossible with the aforementioned techniques. However, due to differences in bonding structure, Raman spectroscopy serves as an ideal candidate for polymorph differentiation. In this work, a correlative approach utilizing Raman spectroscopy for targeted focused ion beam specimen preparation was employed. Dark field imaging and diffraction in the transmission electron microscope confirmed the region of interest located via Raman spectroscopy and demonstrated the validity of this new method. Correlative Raman spectroscopy, scanning electron microscopy, and focused ion beam is shown to be a promising new technique for identifying site-specific preparation of nanoscale specimens in cases where conventional approaches do not suffice.

  15. Treatment of toluene and its by-products using an electron beam/ultra-fine bubble hybrid system

    Science.gov (United States)

    Son, Youn-Suk; Kim, Tae-Hun; Choi, Chang Yong; Park, Jun-Hyeong; Ahn, Ji-Won; Dinh, Trieu-Vuong

    2018-03-01

    Although, until quite recently, many technologies (electron beam (EB), plasma, and ultraviolet) have been studied to overcome disadvantages of conventional methods (such as absorption, adsorption, biofiltration and incineration) for treatment of volatile organic compounds (VOCs), their techniques still have some problems such as formation of a by-product. Generally, it is reported that various by-products are generated from the EB irradiation process to remove VOCs. Therefore, we developed an electron beam/ultra-fine bubble (EB/UB) hybrid system to enhance removal efficiency of a VOC (toluene) and to reduce its by-products formed by electron beam irradiation. As a result, the removal efficiency of toluene (30 ppm) by only EB (10 kGy) was 80.1%. However, the removal efficiency of toluene using the hybrid system (water temperature: 5 ℃) was increased up to 17% when compared to only EB (10 kGy). Additionally, the 65.2% of ozone formed from the EB process was removed in UB reactor. In case of other trace by-products such as undesired VOCs and aldehydes, the levels were lowered down to the below detection limit by the subsequent UB reactor. We also found that the amount of toluene collected and solubilized into water is affected by the water temperature in the UB reactor.

  16. Plasmonic resonance scattering from silver nanowire illuminated by tightly focused singular beam.

    Science.gov (United States)

    Normatov, Alexander; Spektor, Boris; Leviatan, Yehuda; Shamir, Joseph

    2010-08-15

    We investigate scattering features of tightly focused singular beams by placing a cylindrical nanowire in the vicinity of a line phase singularity. Applying an illumination wavelength corresponding to silver cylinder plasmonic resonance, we compare the scattering response with that of a perfect conductor. The rigorous modeling employs a 2D version of the Richards-Wolf focusing method and the source model technique. It is found that a cylinder with a plasmonic resonance produces a strong scattering response by deflecting the power flow toward the optical singularity region, where otherwise the power approaches zero.

  17. TOPICAL REVIEW: Nanofabrication by advanced electron microscopy using intense and focused beam

    Directory of Open Access Journals (Sweden)

    Kazuo Furuya

    2008-01-01

    Full Text Available The nanogrowth and nanofabrication of solid substances using an intense and focused electron beam are reviewed in terms of the application of scanning and transmission electron microscopy (SEM, TEM and STEM to control the size, position and structure of nanomaterials. The first example discussed is the growth of freestanding nanotrees on insulator substrates by TEM. The growth process of the nanotrees was observed in situ and analyzed by high-resolution TEM (HRTEM and was mainly controlled by the intensity of the electron beam. The second example is position- and size-controlled nanofabrication by STEM using a focused electron beam. The diameters of the nanostructures grown ranged from 4 to 20 nm depending on the size of the electron beam. Magnetic nanostructures were also obtained using an iron-containing precursor gas, Fe(CO5. The freestanding iron nanoantennas were examined by electron holography. The magnetic field was observed to leak from the nanostructure body which appeared to act as a 'nanomagnet'. The third example described is the effect of a vacuum on the size and growth process of fabricated nanodots containing W in an ultrahigh-vacuum field-emission TEM (UHV-FE-TEM. The size of the dots can be controlled by changing the dose of electrons and the partial pressure of the precursor. The smallest particle size obtained was about 1.5 nm in diameter, which is the smallest size reported using this method. Finally, the importance of a smaller probe and a higher electron-beam current with atomic resolution is emphasized and an attempt to develop an ultrahigh-vacuum spherical aberration corrected STEM (Cs-corrected STEM at NIMS is reported.

  18. Drift Compression and Final Focus for Intense Heavy Ion Beams with Non-periodic, Time-dependent Lattice

    International Nuclear Information System (INIS)

    Hong Qin; Davidson, Ronald C.; Barnard, John J.; Lee, Edward P.

    2005-01-01

    In the currently envisioned configurations for heavy ion fusion, it is necessary to longitudinally compress the beam bunches by a large factor after the acceleration phase. Because the space-charge force increases as the beam is compressed, the beam size in the transverse direction will increase in a periodic quadrupole lattice. If an active control of the beam size is desired, a larger focusing force is needed to confine the beam in the transverse direction, and a non-periodic quadrupole lattice along the beam path is necessary. In this paper, we describe the design of such a focusing lattice using the transverse envelope equations. A drift compression and final focus lattice should focus the entire beam pulse onto the same focal spot on the target. This is difficult with a fixed lattice, because different slices of the beam may have different perveance and emittance. Four time-dependent magnets are introduced in the upstream of drift compression to focus the entire pulse onto the sam e focal spot. Drift compression and final focusing schemes are developed for a typical heavy ion fusion driver and for the Integrated Beam Experiment (IBX) being designed by the Heavy Ion Fusion Virtual National Laboratory

  19. Evaluating Red Reflex and Surgeon Preference Between Nearly-Collimated and Focused Beam Microscope Illumination Systems.

    Science.gov (United States)

    Cionni, Robert J; Pei, Ron; Dimalanta, Ramon; Lubeck, David

    2015-08-01

    To evaluate the intensity and stability of the red reflex produced by ophthalmic surgical microscopes with nearly-collimated versus focused illumination systems and to assess surgeon preference in a simulated surgical setting. This two-part evaluation consisted of postproduction surgical video analysis of red reflex intensity and a microscope use and preference survey completed by 13 experienced cataract surgeons. Survey responses were based on bench testing and experience in a simulated surgical setting. A microscope with nearly-collimated beam illumination and two focused beam microscopes were assessed. Red reflex intensity and stability were greater with the nearly-collimated microscope illumination system. In the bench testing survey, surgeons reported that the red reflex was maintained over significantly greater distances away from pupillary center, and depth of focus was numerically greater with nearly-collimated illumination relative to focused illumination. Most participating surgeons (≥64%) reported a preference for the microscope with nearly-collimated illumination with regard to red reflex stability, depth of focus, visualization, surgical working distance, and perceived patient comfort. The microscope with nearly-collimated illumination produced a more intense and significantly more stable red reflex and was preferred overall by more surgeons. This is the first report of an attempt to quantify red reflex intensity and stability and to evaluate surgically-relevant parameters between microscope systems. The data and methods presented here may provide a basis for future studies attempting to quantify differences between surgical microscopes that may affect surgeon preference and microscope use in ophthalmic surgery.

  20. Chemical degradation and morphological instabilities during focused ion beam prototyping of polymers.

    Science.gov (United States)

    Orthacker, A; Schmied, R; Chernev, B; Fröch, J E; Winkler, R; Hobisch, J; Trimmel, G; Plank, H

    2014-01-28

    Focused ion beam processing of low melting materials, such as polymers or biological samples, often leads to chemical and morphological instabilities which prevent the straight-forward application of this versatile direct-write structuring method. In this study the behaviour of different polymer classes under ion beam exposure is investigated using different patterning parameters and strategies with the aim of (i) correlating local temperatures with the polymers' chemistry and its morphological consequences; and (ii) finding a way of processing sensitive polymers with lowest chemical degradation while maintaining structuring times. It is found that during processing of polymers three temperature regimes can be observed: (1) at low temperatures all polymers investigated show stable chemical and morphological behaviour; (2) very high temperatures lead to strong chemical degradation which entails unpredictable morphologies; and (3) in the intermediate temperature regime the behaviour is found to be strongly material dependent. A detailed look reveals that polymers which rather cross-link in the proximity of the beam show stable morphologies in this intermediate regime, while polymers that rather undergo chain scission show tendencies to develop a creeping phase, where material follows the ion beam movement leading to instable and unpredictable morphologies. Finally a simple, alternative patterning strategy is suggested, which allows stable processing conditions with lowest chemical damage even for challenging polymers undergoing chain scission.

  1. Fabrication of phonon-based metamaterial structures using focused ion beam patterning

    Science.gov (United States)

    Bassim, Nabil D.; Giles, Alexander J.; Ocola, Leonidas E.; Caldwell, Joshua D.

    2018-02-01

    The focused ion beam (FIB) is a powerful tool for rapid prototyping and machining of functional nanodevices. It is employed regularly to fabricate test metamaterial structures but, to date, has been unsuccessful in fabricating metamaterial structures with features at the nanoscale that rely on surface phonons as opposed to surface plasmons because of the crystalline damage that occurs with the collision cascade associated with ion sputtering. In this study, we employ a simple technique of protecting the crystalline substrate in single-crystal 4H-SiC to design surface phonon polariton-based optical resonance structures. By coating the material surface with a thin film of chromium, we have placed a material of high sputter resistance on the surface, which essentially absorbs the energy in the beam tails. When the beam ultimately punches through the Cr film, the hard walls in the film have the effect of channeling the beam to create smooth sidewalls. This demonstration opens the possibility of further rapid-prototyping of metamaterials using FIB.

  2. Focused particle beam nano-machining: the next evolution step towards simulation aided process prediction

    International Nuclear Information System (INIS)

    Plank, Harald

    2015-01-01

    During the last decade, focused ion beam processing has been developed from traditionally used Ga + liquid ion sources towards higher resolution gas field ion sources (He + and Ne + ). Process simulations not only improve the fundamental understanding of the relevant ion–matter interactions, but also enable a certain predictive power to accelerate advances. The historic ‘gold’ standard in ion–solid simulations is the SRIM/TRIM Monte Carlo package released by Ziegler, Ziegler and Biersack 2010 Nucl. Instrum. Methods B 268 1818–23. While SRIM/TRIM is very useful for a myriad of applications, it is not applicable for the understanding of the nanoscale evolution associated with ion beam nano-machining as the substrate does not evolve with the sputtering process. As a solution for this problem, a new, adapted simulation code is briefly overviewed and finally addresses these contributions. By that, experimentally observed Ne + beam sputter profiles can be explained from a fundamental point of view. Due to their very good agreement, these simulations contain the potential for computer aided optimization towards predictable sputter processes for different nanotechnology applications. With these benefits in mind, the discussed simulation approach represents an enormous step towards a computer based master tool for adaptable ion beam applications in the context of industrial applications. (viewpoint)

  3. Bright focused ion beam sources based on laser-cooled atoms

    Energy Technology Data Exchange (ETDEWEB)

    McClelland, J. J.; Wilson, T. M. [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Steele, A. V.; Knuffman, B.; Schwarzkopf, A. [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); zeroK NanoTech, Gaithersburg, Maryland 20878 (United States); Twedt, K. A. [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Maryland Nanocenter, University of Maryland, College Park, Maryland 20742 (United States)

    2016-03-15

    Nanoscale focused ion beams (FIBs) represent one of the most useful tools in nanotechnology, enabling nanofabrication via milling and gas-assisted deposition, microscopy and microanalysis, and selective, spatially resolved doping of materials. Recently, a new type of FIB source has emerged, which uses ionization of laser cooled neutral atoms to produce the ion beam. The extremely cold temperatures attainable with laser cooling (in the range of 100 μK or below) result in a beam of ions with a very small transverse velocity distribution. This corresponds to a source with extremely high brightness that rivals or may even exceed the brightness of the industry standard Ga{sup +} liquid metal ion source. In this review, we discuss the context of ion beam technology in which these new ion sources can play a role, their principles of operation, and some examples of recent demonstrations. The field is relatively new, so only a few applications have been demonstrated, most notably low energy ion microscopy with Li ions. Nevertheless, a number of promising new approaches have been proposed and/or demonstrated, suggesting that a rapid evolution of this type of source is likely in the near future.

  4. Tunable magic wavelengths for trapping with focused Laguerre-Gaussian beams

    Science.gov (United States)

    Bhowmik, Anal; Dutta, Narendra Nath; Majumder, Sonjoy

    2018-02-01

    We present in this paper a theory of dynamic polarizability for an atomic state due to an external field of nonparaxial Laguerre-Gaussian (LG) beam using the sum-over-states technique. A highly correlated relativistic coupled-cluster theory is used to evaluate the most important and correlation-sensitive parts of the sum. The theory is applied on Sr+ to determine the magic wavelengths for 5 s1 /2→4 d3 /2,4 d5 /2 transitions. Results show the variation of magic wavelengths with the choice of orbital and spin angular momenta of the incident LG beam. Also, the tunability of the magic wavelengths is studied by using the focusing angle of the LG beam and its efficiency in the near-infrared region is observed. Evaluations of the wide spectrum of magic wavelengths from infrared to ultraviolet have substantial importance to experimentalists for carrying out high-precision measurements in fundamental physics. These magic wavelengths can be used to confine the atom or ion at the dark central node or at the high-intensity ring of the LG beam.

  5. Bright focused ion beam sources based on laser-cooled atoms

    Science.gov (United States)

    McClelland, J. J.; Steele, A. V.; Knuffman, B.; Twedt, K. A.; Schwarzkopf, A.; Wilson, T. M.

    2016-01-01

    Nanoscale focused ion beams (FIBs) represent one of the most useful tools in nanotechnology, enabling nanofabrication via milling and gas-assisted deposition, microscopy and microanalysis, and selective, spatially resolved doping of materials. Recently, a new type of FIB source has emerged, which uses ionization of laser cooled neutral atoms to produce the ion beam. The extremely cold temperatures attainable with laser cooling (in the range of 100 μK or below) result in a beam of ions with a very small transverse velocity distribution. This corresponds to a source with extremely high brightness that rivals or may even exceed the brightness of the industry standard Ga+ liquid metal ion source. In this review we discuss the context of ion beam technology in which these new ion sources can play a role, their principles of operation, and some examples of recent demonstrations. The field is relatively new, so only a few applications have been demonstrated, most notably low energy ion microscopy with Li ions. Nevertheless, a number of promising new approaches have been proposed and/or demonstrated, suggesting that a rapid evolution of this type of source is likely in the near future. PMID:27239245

  6. 3D micro-optical elements for generation of tightly focused vortex beams

    Directory of Open Access Journals (Sweden)

    Balčytis Armandas

    2015-01-01

    Full Text Available Orbital angular momentum carrying light beams are usedfor optical trapping and manipulation. This emerging trend provides new challenges involving device miniaturization for improved performance and enhanced functionality at the microscale. Here we discus a new fabrication method based on combining the additive 3D structuring capability laser photopolymerization and the substractive sub-wavelength resolution patterning of focused ion beam lithography to produce micro-optical elements capable of compound functionality. As a case in point of this approach binary spiral zone pattern based high numerical aperture micro-lenses capable of generating topological charge carrying tightly focused vortex beams in a single wavefront transformation step are presented. The devices were modelled using finite-difference time-domain simulations, and the theoretical predictions were verified by optically characterizing the propagation properties of light transmitted through the fabricated structures. The resulting devices had focal lengths close to the predicted values of f = 18 µm and f = 13 µm as well as topological charge ℓ dependent vortex focal spot sizes of ~ 1:3 µm and ~ 2:0 µm for ℓ = 1 and ℓ = 2 respectively.

  7. Applications of focused MeV light ion beams for high resolution channeling contrast imaging

    Energy Technology Data Exchange (ETDEWEB)

    Jamieson, D.N.; Breese, M.B.H.; Prawer, S.; Dooley, S.P.; Allen, M.G.; Bettiol, A.A.; Saint, A. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Ryan, C.G. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), North Ryde, NSW (Australia). Div. of Exploration Geoscience

    1993-12-31

    The technique of Nuclear Microscopy, utilizing a focused ion probe of typically MeV H{sup +} or He{sup +} ions, can produce images where the contrast depends on typical Ion Beam Analysis (lBA) processes. The probe forming lens system usually utilizes strong focusing, precision magnetic quadrupole lenses and the probe is scanned over the target to produce images. Originally, this imaging technique was developed to utilize backscattered particles with incident beam currents typically of a few nA, and the technique became known as Channeling Contrast Microscopy (CCM). Recently, the technique has been developed further to utilize the forward scattering of ions incident along a major crystal axis in thin crystals. This technique is known as Channeling Scanning Transmission Ion Microscopy (CSTIM). Since nearly all incident ions are detected, CSTIM is highly efficient and very low beam currents are sufficient for imaging, typically as low as a few fA. This allows probes as small as 50 nm to be used. In this paper we briefly review the recent applications of these emerging techniques to a variety of single crystal materials (authors). 13 refs., 5 figs.

  8. Shaping symmetric Airy beam through binary amplitude modulation for ultralong needle focus

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Zhao-Xiang; Gong, Lei [Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei 230026 (China); Ren, Yu-Xuan, E-mail: yxren@ustc.edu.cn [National Center for Protein Sciences Shanghai, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Shanghai 200031 (China); Vaveliuk, Pablo [Centro de Investigaciones Opticas (CONICET La Plata-CIC), Cno. Centenario y 506, P.O. Box 3, 1897 Gonnet, La Plata, Pcia. de Buenos Aires (Argentina); Chen, Yue; Lu, Rong-De, E-mail: lrd@ustc.edu.cn [Physics Experiment Teaching Center, School of Physical Sciences, University of Science and Technology of China, Hefei 230026 (China)

    2015-11-28

    Needle-like electromagnetic field has various advantages for the applications in high-resolution imaging, Raman spectroscopy, as well as long-distance optical transportation. The realization of such field often requires high numerical aperture (NA) objective lens and the transmission masks. We demonstrate an ultralong needle-like focus in the optical range produced with an ordinary lens. This is achieved by focusing a symmetric Airy beam (SAB) generated via binary spectral modulation with a digital micromirror device. Such amplitude modulation technique is able to shape traditional Airy beams, SABs, as well as the dynamic transition modes between the one-dimensional and two-dimensional (2D) symmetric Airy modes. The created 2D SAB was characterized through measurement of the propagating fields with one of the four main lobes blocked by an opaque mask. The 2D SAB was verified to exhibit self-healing property against propagation with the obstructed major lobe reconstructed after a certain distance. We further produced an elongated focal line by concentrating the SAB via lenses with different NAs and achieved an ultralong longitudinal needle focus. The produced long needle focus will be applied in optical, chemical, and biological sciences.

  9. High-gradient microelectromechanical system quadrupole electromagnets for particle beam focusing and steering

    Directory of Open Access Journals (Sweden)

    Jere Harrison

    2015-02-01

    Full Text Available Recent advancements in microelectromechanical system (MEMS fabrication techniques have enabled the batch-fabrication of quadrupole MEMS electromagnets producing 100 mT-scale field across sub-mm gaps with the potential for transformational advances in the field of compact high performance charged particle focusing and steering optics. The footprint of these in-vacuum focusing and steering optics can be as small as 3  mm×3  mm×0.5  mm. The low electromagnet impedance (58  mΩ, 32 nH per pole facilitates power-efficient operation and continuous or low duty cycle operation, and the individually controlled electromagnets allow combined dipole-quadrupole fields. Here we report on an experiment where these miniature devices have been used to focus and steer a 34 keV electron beam from a DC photogun, demonstrating the first application of magnetic MEMS to particle beam focusing.

  10. Self-consistent beam halo studies ampersand halo diagnostic development in a continuous linear focusing channel

    International Nuclear Information System (INIS)

    Jameson, R.A.

    1994-01-01

    Beam halos are formed via self-consistent motion of the beam particles. Interactions of single particles with time-varying density distributions of other particles are a major source of halo. Aspects of these interactions are studied for an initially equilibrium distribution in a radial, linear, continuous focusing system. When there is a mismatch, it is shown that in the self-consistent system, there is a threshold in space-charge and mismatch, above which a halo is formed that extends to ∼1.5 times the initial maximum mismatch radius. Tools are sought for characterizing the halo dynamics. Testing the particles against the width of the mismatch driving resonance is useful for finding a conservative estimate of the threshold. The exit, entering and transition times, and the time evolution of the halo, are also explored using this technique. Extension to higher dimensions is briefly discussed

  11. High resolution laser beam induced current focusing for photoactive surface characterization

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Lorenzo, C. [Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Cadiz, Apartado de Correos 40, 11510 Puerto Real, Cadiz (Spain)]. E-mail: concha.fernandez@uca.es; Poce-Fatou, J.A. [Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Cadiz, Apartado de Correos 40, 11510 Puerto Real, Cadiz (Spain); Alcantara, R. [Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Cadiz, Apartado de Correos 40, 11510 Puerto Real, Cadiz (Spain); Navas, J. [Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Cadiz, Apartado de Correos 40, 11510 Puerto Real, Cadiz (Spain); Martin, J. [Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Cadiz, Apartado de Correos 40, 11510 Puerto Real, Cadiz (Spain)

    2006-12-15

    The micro-characterization of several surface properties of the solar cells can be accomplished using high-resolution laser beam induced current images. For obtaining these images, a very precise laser beam focusing on the photoactive surface is required. For this purpose, a methodology for obtaining the best focalization associated to the maximum of a peak curve has been developed. In this paper, a data set, obtained from the inner photoconversion properties of the system, has been evaluated with three different numerical analysis techniques: (a) derivative (b) length and (c) Fourier Transform, in order to get the finest possible peak distribution. Then, an amount of 13 analytical peak curves using the Levenberg Marquardt algorithm to find the best curve that adjusts the data distribution have been analyzed.

  12. Preparation and Analysis of Atom Probe Tips by Xenon Focused Ion Beam Milling.

    Science.gov (United States)

    Estivill, Robert; Audoit, Guillaume; Barnes, Jean-Paul; Grenier, Adeline; Blavette, Didier

    2016-06-01

    The damage and ion distribution induced in Si by an inductively coupled plasma Xe focused ion beam was investigated by atom probe tomography. By using predefined patterns it was possible to prepare the atom probe tips with a sub 50 nm end radius in the ion beam microscope. The atom probe reconstruction shows good agreement with simulated implantation profiles and interplanar distances extracted from spatial distribution maps. The elemental profiles of O and C indicate co-implantation during the milling process. The presence of small disc-shaped Xe clusters are also found in the three-dimensional reconstruction. These are attributed to the presence of Xe nanocrystals or bubbles that open during the evaporation process. The expected accumulated dose points to a loss of >95% of the Xe during analysis, which escapes undetected.

  13. Ultraviolet Beam Focusing in Gallium Arsenide by Direct Excitation of Surface Plasmon Polaritons

    Directory of Open Access Journals (Sweden)

    Senfeng Lai

    2015-01-01

    Full Text Available This paper proposed that ultraviolet beam could be focused by gallium arsenide (GaAs through direct excitation of surface plasmon polaritons. Both theoretical analysis and computer simulation showed that GaAs could be a reasonably good plasmonic material in the air in the deep ultraviolet waveband. With a properly designed bull’s eye structure etched in GaAs, the ultraviolet electric field could be enhanced to as high as 20 times the incident value, and the full-width-half-maximum (FWHM of the light beam could be shrunk from ~48° to ~6°. As a plasmonic material, GaAs was compared to Ag and Al. Within the studied ultraviolet waveband, the field enhancement in GaAs was much stronger than Ag but not as high as Al.

  14. A novel beam focus control at the entrance to the ANU 14UD accelerator

    Directory of Open Access Journals (Sweden)

    De Cesare M.

    2013-12-01

    Full Text Available Tandem electrostatic accelerators often require the flexibility to operate at variety of terminal voltages to cater for various user needs. However beam transmission will only be optimal for a limited range of terminal voltages. This paper describes a focussing system that greatly expands the range of terminal voltages for optimal transmission. This is achieved by controlling the gradient of the entrance of the low-energy tube providing an additional controllable focusing element. Up to 150 kV is applied to the fifth electrode of the first unit of the accelerator tube giving control of the tube entrance lens strength. Beam tests to confirm the efficacy of the lens have been performed. These tests demonstrate that the entrance lens control eliminates the need to short out sections of the tube for low terminal voltage operation.

  15. Measurements of fast electron beams and soft X-ray emission from plasma-focus experiments

    Directory of Open Access Journals (Sweden)

    Surała Władysław

    2016-06-01

    Full Text Available The paper reports results of the recent experimental studies of pulsed electron beams and soft X-rays in plasma-focus (PF experiments carried out within a modified PF-360U facility at the NCBJ, Poland. Particular attention was focused on time-resolved measurements of the fast electron beams by means of two different magnetic analyzers, which could record electrons of energy ranging from about 41 keV to about 715 keV in several (6 or 8 measuring channels. For discharges performed with the pure deuterium filling, many strong electron signals were recorded in all the measuring channels. Those signals were well correlated with the first hard X-ray pulse detected by an external scintillation neutron-counter. In some of the analyzer channels, electron spikes (lasting about dozens of nanoseconds and appearing in different instants after the current peculiarity (so-called current dip were also recorded. For several discharges, fast ion beams, which were emitted along the z-axis and recorded with nuclear track detectors, were also investigated. Those measurements confirmed a multibeam character of the ion emission. The time-integrated soft X-ray images, which were taken side-on by means of a pinhole camera and sensitive X-ray films, showed the appearance of some filamentary structures and so-called hot spots. The application of small amounts of admixtures of different heavy noble gases, i.e. of argon (4.8% volumetric, krypton (1.6% volumetric, or xenon (0.8% volumetric, decreased intensity of the recorded electron beams, but increased intensity of the soft X-ray emission and showed more distinct and numerous hot spots. The recorded electron spikes have been explained as signals produced by quasi-mono-energetic microbeams emitted from tiny sources (probably plasma diodes, which can be formed near the observed hot spots.

  16. Focusing a laser beam by means of an off-centre parabolic mirror

    International Nuclear Information System (INIS)

    Rostaing, Michel.

    In this study particular attention was paid to defining and optimizing a focusing system for concentrating a CO 2 laser beam (wave length lambda = 10.6 μm) on to a target containing a deuterium and tritium mixture. A digital study of the focusing of a spherical wave, in conjunction with the examination of the properties of reflecting surfaces led to the development of a focusing device using an off-centre parabolic mirror. Despite an aberration of 6 μm in the mirror, the lighting achieved experimentally in the plane of the circle of least scattering is 1.6 times greater than that achieved during the use of an NaCl spherical plane lense [fr

  17. Super-resolution longitudinally polarized light needle achieved by tightly focusing radially polarized beams

    Science.gov (United States)

    Shi, Chang-kun; Nie, Zhong-quan; Tian, Yan-ting; Liu, Chao; Zhao, Yong-chuang; Jia, Bao-hua

    2018-01-01

    Based on the vector diffraction theory, a super-resolution longitudinally polarized optical needle with ultra-long depth of focus ( DOF) is generated by tightly focusing a radially polarized beam that is modulated by a self-designed ternary hybrid (phase/amplitude) filter (THF). Both the phase and the amplitude patterns of THF are judiciously optimized by the versatile particle swarm optimization (PSO) searching algorithm. For the focusing configuration with a combination of a high numerical aperture ( NA) and the optimized sine-shaped THFs, an optical needle with the full width at half maximum ( FWHM) of 0.414λ and the DOF of 7.58λ is accessed, which corresponds to an aspect ratio of 18.3. The demonstrated longitudinally polarized super-resolution light needle with high aspect ratio opens up broad applications in high-density optical data storage, nano-photolithography, super-resolution imaging and high-efficiency particle trapping.

  18. Countering beam divergence effects with focused segmented scintillators for high DQE megavoltage active matrix imagers.

    Science.gov (United States)

    Liu, Langechuan; Antonuk, Larry E; Zhao, Qihua; El-Mohri, Youcef; Jiang, Hao

    2012-08-21

    The imaging performance of active matrix flat-panel imagers designed for megavoltage imaging (MV AMFPIs) is severely constrained by relatively low x-ray detection efficiency, which leads to a detective quantum efficiency (DQE) of only ∼1%. Previous theoretical and empirical studies by our group have demonstrated the potential for addressing this constraint through the utilization of thick, two-dimensional, segmented scintillators with optically isolated crystals. However, this strategy is constrained by the degradation of high-frequency DQE resulting from spatial resolution loss at locations away from the central beam axis due to oblique incidence of radiation. To address this challenge, segmented scintillators constructed so that the crystals are individually focused toward the radiation source are proposed and theoretically investigated. The study was performed using Monte Carlo simulations of radiation transport to examine the modulation transfer function and DQE of focused segmented scintillators with thicknesses ranging from 5 to 60 mm. The results demonstrate that, independent of scintillator thickness, the introduction of focusing largely restores spatial resolution and DQE performance otherwise lost in thick, unfocused segmented scintillators. For the case of a 60 mm thick BGO scintillator and at a location 20 cm off the central beam axis, use of focusing improves DQE by up to a factor of ∼130 at non-zero spatial frequencies. The results also indicate relatively robust tolerance of such scintillators to positional displacements, of up to 10 cm in the source-to-detector direction and 2 cm in the lateral direction, from their optimal focusing position, which could potentially enhance practical clinical use of focused segmented scintillators in MV AMFPIs.

  19. Perspective: Extremely fine tuning of doping enabled by combinatorial molecular-beam epitaxy

    Directory of Open Access Journals (Sweden)

    J. Wu

    2015-06-01

    Full Text Available Chemical doping provides an effective method to control the electric properties of complex oxides. However, the state-of-art accuracy in controlling doping is limited to about 1%. This hampers elucidation of the precise doping dependences of physical properties and phenomena of interest, such as quantum phase transitions. Using the combinatorial molecular beam epitaxy, we improve the accuracy in tuning the doping level by two orders of magnitude. We illustrate this novel method by two examples: a systematic investigation of the doping dependence of interface superconductivity, and a study of the competing ground states in the vicinity of the insulator-to-superconductor transition.

  20. On the feasibility of the Chevron Notch Beam method to measure fracture toughness of fine-grained zirconia ceramics.

    Science.gov (United States)

    Kailer, Andreas; Stephan, Marc

    2016-10-01

    The fracture toughness determination of fine-grained zirconia ceramics using the chevron notched beam method (CNB) was investigated to assess the feasibility of this method for quality assurance and material characterization. CNB tests were performed using four different yttria-stabilized zirconia ceramics under various testing modes and conditions, including displacement-controlled and load-rate-controlled four point bending to assess the influence of slow crack growth and identify most suitable test parameters. For comparison, tests using single-edge V-notch beams (SEVNB) were conducted. It was observed that the CNB method yields well-reproducible results. However, slow crack growth effects significantly affect the measured KIC values, especially when slow loading rates are used. To minimize the effect of slow crack growth, the application of high loading rates is recommended. Despite a certain effort needed for setting up a sample preparation routine, the CNB method is considered to be very useful for measuring and controlling the fracture toughness of zirconia ceramics. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  1. Stabilization and Fine Positioning to the Nanometre Level of the CLIC Main Beam Quadrupoles

    CERN Document Server

    Artoos, K; Fernandez Carmona, P; Guinchard, M; Hauviller, C; Janssens, S; Kuzmin, A; Lackner, F; Leuxe, R; Slaathaug, A

    2010-01-01

    The CLIC main beam quadrupoles need to be stabilized to 1.5 nm integrated R.M.S. displacement at 1 Hz. The choice was made to apply active stabilization with piezoelectric actuators in a rigid support with flexural guides. The advantages of this choice are the robustness against external forces and the possibility to make fast incremental nanometre positioning of the magnet with the same actuators. The study and feasibility demonstration is made in several steps from a single degree of freedom system (s.d.o.f.) with a small mass, a s.d.o.f. with a large mass, leading to the demonstration including the smallest (type 1) and largest (type 4) CLIC main beam quadrupoles. The paper discusses the choices of the position and orientation of the actuators and the tailored rigidities of the flexural hinges in the multi degree of freedom system, and the corresponding MIMO control system. The compatibility with the magnet support and micrometre alignment system is essential. The status of the study and performed tests wi...

  2. Read/write characteristics of focused-ion-beam-etched heads for perpendicular magnetic recording media

    International Nuclear Information System (INIS)

    Tsuboi, S.; Matsutera, H.; Ishi, T.; Ishiwata, N.; Ohashi, K.

    2001-01-01

    The read/write characteristics for perpendicular magnetic recording media of focused-ion-beam (FIB)-etched recording heads were investigated. It was found that the trailing edge of an FIB-etched head produces a higher gradient in the magnetic field perpendicular to the medium than a head which has not been etched. The signal-to-noise ratio of the medium increased with the FIB-etched write gap. A high-Bs and thin pole increased the magnetic field's gradient in the perpendicular direction, resulting in excellent read/write characteristics

  3. Machining with micro-size single crystalline diamond tools fabricated by a focused ion beam

    International Nuclear Information System (INIS)

    Ding, X; Butler, D L; Lim, G C; Shaw, K C; Liu, K; Fong, W S; Zheng, H Y; Cheng, C K

    2009-01-01

    A study was carried out to understand the physics of micro-scale mechanical machining (henceforth referred to as 'micro-machining') with a micro-size tool using a five-axis ultra-precision machine. A micro-size single crystalline diamond (SCD) tool with sharp cutting edges fabricated by a focused ion beam (FIB) was employed to orthogonal-machine four materials (three polycrystalline metals with various grain sizes and one amorphous metal plating material). Since the wealth of knowledge of macro-machining cannot be successfully used in micro-machining, this study contributes to the understanding of the physics of mechanical machining with micro-size tools

  4. Simulation of Electron Beam Transport in Ion-Focused Regime Conditioning Cells

    Science.gov (United States)

    1992-07-21

    leflhron Davis lgharay. Swft, I M. Arlington. VA 22Z02.4302. and to the office of Management and Budget. Paperwork Reduction Protect (07044 1in). Wahngon...nb(r, rz) and nh(r, rz) are the beam and ion densities, respectively, and vi is the gas ionization rate. In sir at pressure P, vi =P(torr) nsecŕ . In... Humphries and Ekdah156 and Fernsler, et al.57 FRIEZR employs a variation of Adler’s thin lens approximation to treat foil focusing. The impulse has the

  5. Interface failure and adhesion measured by focused ion beam cutting of metal-polymer interfaces

    Science.gov (United States)

    Cordill, M. J.; Schmidegg, K.; Dehm, G.

    2011-08-01

    New developments in flexible electronics require metal films to adhere to polymer substrates. Measuring the interfacial adhesion of these systems is challenging, requiring the formulation of new techniques and models. A strategy to measure the adhesion of Cr-polyethylene terephthalate (PET) interfaces using tensile straining and buckle formation is presented in this article. Focused ion beam cross-sectioning of the buckles reveals that the polymer substrate can locally fail, which may lead to an overestimate of adhesion. Cr-PET adhesion energy of 9.4 ± 1.6 J/m2 is determined with the present approach.

  6. The proposed alignment system for the Final Focus Test Beam at SLAC

    International Nuclear Information System (INIS)

    Ruland, R.E.; Fischer, G.E.

    1990-09-01

    This report describes the current state of work in progress with respect to the geometry, alignment requirements, scenarios, and hardware for meeting the tolerances of the Final Focus Test Beam (FFTB) at SLAC. The methods and systems proposed acknowledge that component motion at the micron level, from whatever cause (ground motion, thermal effects, etc.) must be measured on-line and compensated for on relatively short time scales. To provide an integrated alignment/positioning package, some unique designs for reference systems, calibration of effect electric and magnetic centers, and component movers are introduced. 24 refs., 28 figs

  7. Evaluating Red Reflex and Surgeon Preference Between Nearly-Collimated and Focused Beam Microscope Illumination Systems

    Science.gov (United States)

    Cionni, Robert J.; Pei, Ron; Dimalanta, Ramon; Lubeck, David

    2015-01-01

    Purpose To evaluate the intensity and stability of the red reflex produced by ophthalmic surgical microscopes with nearly-collimated versus focused illumination systems and to assess surgeon preference in a simulated surgical setting. Methods This two-part evaluation consisted of postproduction surgical video analysis of red reflex intensity and a microscope use and preference survey completed by 13 experienced cataract surgeons. Survey responses were based on bench testing and experience in a simulated surgical setting. A microscope with nearly-collimated beam illumination and two focused beam microscopes were assessed. Results Red reflex intensity and stability were greater with the nearly-collimated microscope illumination system. In the bench testing survey, surgeons reported that the red reflex was maintained over significantly greater distances away from pupillary center, and depth of focus was numerically greater with nearly-collimated illumination relative to focused illumination. Most participating surgeons (≥64%) reported a preference for the microscope with nearly-collimated illumination with regard to red reflex stability, depth of focus, visualization, surgical working distance, and perceived patient comfort. Conclusions The microscope with nearly-collimated illumination produced a more intense and significantly more stable red reflex and was preferred overall by more surgeons. Translational Relevance This is the first report of an attempt to quantify red reflex intensity and stability and to evaluate surgically-relevant parameters between microscope systems. The data and methods presented here may provide a basis for future studies attempting to quantify differences between surgical microscopes that may affect surgeon preference and microscope use in ophthalmic surgery. PMID:26290778

  8. Effect of Travel Speed and Beam Focus on Porosity in Alloy 690 Laser Welds

    Science.gov (United States)

    Tucker, Julie D.; Nolan, Terrance K.; Martin, Anthony J.; Young, George A.

    2012-12-01

    Advances in laser welding technology, including fiber optic delivery and high power density, are increasing the applicability of this joining technique. The inherent benefits of laser welding include small heat-affected zones, minimal distortion, and limited susceptibility to cracking. These advantages are of special interest to next-generation nuclear power systems where welding solute-rich alloys is expected to increase. Alloy 690 (A690) is an advanced corrosion-resistant structural material used in many replacement components and in construction of new commercial power plants. However, the application of A690 is hindered by its difficult weldability using conventional arc welding, and laser welding is a promising alternate. This work studies the effects of travel speed and beam focus on porosity formation in partial penetration, autogenous A690 laser welds. Porosity has been characterized by light optical microscopy and x-ray computed tomography to quantify its percent volume in the welds. This work describes the tradeoff between weld penetration and defect density as a function of beam defocus and travel speed. Additionally, the role of shield gas in porosity formation is discussed to provide a mitigation strategy for A690 laser welding. A process map is provided that shows the optimal combinations of travel speed and beam defocus to minimize porosity and maximize weld penetration at a laser power of 4 kW.

  9. Fabrication of a side aligned optical fibre interferometer by focused ion beam machining

    International Nuclear Information System (INIS)

    Sun, J; Miller, M K; Ritchie, J M; Luo, X; Li, J; Maier, R R J; Hand, D P; MacPherson, W N

    2013-01-01

    Focused ion beam (FIB) machining is a promising technique for the fabrication of micro-optical components with high quality surface finishes. In this work, a prototype of a side aligned optical fibre interferometer was successfully fabricated by the three-dimensional deterministic FIB machining technique. A highly accurate 45° reflective mirror with surface roughness (Ra) of 10 nm has been successfully fabricated at the centre of the fibre to direct the core guided light to the side of the fibre. A surface topography simulation method was developed to simulate the ion beam polishing process. According to the simulation result, a 0.5° offset on the ion beam polishing direction is necessary to maintain the machining accuracy. In the fabrication process, it was also found that for structures requiring a high aspect ratio the existence of an open edge can mitigate against the material redeposition on the sidewalls and therefore increase the overall material removal rate. The fibre has been tested optically and the interference signals have been successfully observed, demonstrating the alignment accuracy of the fabrication method. (paper)

  10. Application of focused ion beam to atom probe tomography specimen preparation from mechanically alloyed powders.

    Science.gov (United States)

    Choi, Pyuck-Pa; Al-Kassab, Tala'at; Kwon, Young-Soon; Kim, Ji-Soon; Kirchheim, Reiner

    2007-10-01

    Focused ion-beam milling has been applied to prepare needle-shaped atom probe tomography specimens from mechanically alloyed powders without the use of embedding media. The lift-out technique known from transmission electron microscopy specimen preparation was modified to cut micron-sized square cross-sectional blanks out of single powder particles. A sequence of rectangular cuts and annular milling showed the highest efficiency for sharpening the blanks to tips. First atom probe results on a Fe95Cu5 powder mechanically alloyed in a high-energy planetary ball mill for 20 h have been obtained. Concentration profiles taken from this powder sample showed that the Cu distribution is inhomogeneous on a nanoscale and that the mechanical alloying process has not been completed yet. In addition, small clusters of oxygen, stemming from the ball milling process, have been detected. Annular milling with 30 keV Ga ions and beam currents >or=50 pA was found to cause the formation of an amorphous surface layer, whereas no structural changes could be observed for beam currents

  11. Subsurface examination of a foliar biofilm using scanning electron- and focused-ion-beam microscopy.

    Science.gov (United States)

    Wallace, Patricia Kay; Arey, Bruce; Mahaffee, Walter F

    2011-08-01

    The dual beam scanning electron microscope, equipped with both a focused ion- and scanning electron-beam (FIB SEM) is a novel tool for the exploration of the subsurface structure of biological tissues. The FIB can remove a predetermined amount of material from a selected site to allow for subsurface exploration and when coupled with SEM or scanning ion-beam microscopy (SIM) could be suitable to examine the subsurface structure of bacterial biofilms on the leaf surface. The suitability of chemical and cryofixation was examined for use with the FIB SEM to examine bacterial biofilms on leaf surfaces. The biological control agent, Burkholderia pyroccinia FP62, that rapidly colonizes the leaf surface and forms biofilms, was inoculated onto geranium leaves and incubated in a greenhouse for 7 or 14 days. Cryofixation was not suitable for examination of leaf biofilms because it created a frozen layer over the leaf surface that cracked when exposed to the electron beam and the protective cap required for FIB milling could not be accurately deposited. With chemically fixed samples, it was possible to precisely FIB mill a single cross section (5μm) or sequential cross sections from a single site without any damage to the surrounding surface. Biofilms, 7 days post-inoculation (DPI), were composed of 2-5 bacterial cell layers while biofilms 14 DPI ranged from 5 to greater than 30 cell layers. Empty spaces between bacteria cells in the subsurface structure were observed in biofilms 7- and 14-DPI. Sequential cross sections inferred that the empty spaces were often continuous between FP62 cells and could possibly make up a network of channels throughout the biofilm. FIB SEM was a useful tool to observe the subsurface composition of a foliar biofilm. Published by Elsevier Ltd.

  12. Strong self-focusing of a cosh-Gaussian laser beam in collisionless magneto-plasma under plasma density ramp

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, Vikas; Kant, Niti, E-mail: nitikant@yahoo.com [Department of Physics, Lovely Professional University, G. T. Road, Phagwara, Punjab 144411 (India)

    2014-07-15

    The effect of plasma density ramp on self-focusing of cosh-Gaussian laser beam considering ponderomotive nonlinearity is analyzed using WKB and paraxial approximation. It is noticed that cosh-Gaussian laser beam focused earlier than Gaussian beam. The focusing and de-focusing nature of the cosh-Gaussian laser beam with decentered parameter, intensity parameter, magnetic field, and relative density parameter has been studied and strong self-focusing is reported. It is investigated that decentered parameter “b” plays a significant role for the self-focusing of the laser beam as for b=2.12, strong self-focusing is seen. Further, it is observed that extraordinary mode is more prominent toward self-focusing rather than ordinary mode of propagation. For b=2.12, with the increase in the value of magnetic field self-focusing effect, in case of extraordinary mode, becomes very strong under plasma density ramp. Present study may be very useful in the applications like the generation of inertial fusion energy driven by lasers, laser driven accelerators, and x-ray lasers. Moreover, plasma density ramp plays a vital role to enhance the self-focusing effect.

  13. Strong self-focusing of a cosh-Gaussian laser beam in collisionless magneto-plasma under plasma density ramp

    International Nuclear Information System (INIS)

    Nanda, Vikas; Kant, Niti

    2014-01-01

    The effect of plasma density ramp on self-focusing of cosh-Gaussian laser beam considering ponderomotive nonlinearity is analyzed using WKB and paraxial approximation. It is noticed that cosh-Gaussian laser beam focused earlier than Gaussian beam. The focusing and de-focusing nature of the cosh-Gaussian laser beam with decentered parameter, intensity parameter, magnetic field, and relative density parameter has been studied and strong self-focusing is reported. It is investigated that decentered parameter “b” plays a significant role for the self-focusing of the laser beam as for b=2.12, strong self-focusing is seen. Further, it is observed that extraordinary mode is more prominent toward self-focusing rather than ordinary mode of propagation. For b=2.12, with the increase in the value of magnetic field self-focusing effect, in case of extraordinary mode, becomes very strong under plasma density ramp. Present study may be very useful in the applications like the generation of inertial fusion energy driven by lasers, laser driven accelerators, and x-ray lasers. Moreover, plasma density ramp plays a vital role to enhance the self-focusing effect

  14. Broadband acoustic focusing by Airy-like beams based on acoustic metasurfaces

    Science.gov (United States)

    Chen, Di-Chao; Zhu, Xing-Feng; Wei, Qi; Wu, Da-Jian; Liu, Xiao-Jun

    2018-01-01

    An acoustic metasurface (AM) composed of space-coiling subunits is proposed to generate acoustic Airy-like beams (ALBs) by manipulating the transmitted acoustic phase. The self-accelerating, self-healing, and non-diffracting features of ALBs are demonstrated using finite element simulations. We further employ two symmetrical AMs to realize two symmetrical ALBs, resulting in highly efficient acoustic focusing. At the working frequency, the focal intensity can reach roughly 20 times that of the incident wave. It is found that the highly efficient acoustic focusing can circumvent obstacles in the propagating path and can be maintained in a broad frequency bandwidth. In addition, simply changing the separation between the two AMs can modulate the focal length of the proposed AM lens. ALBs generated by AMs and the corresponding AM lens may benefit applications in medical ultrasound imaging, biomedical therapy, and particle trapping and manipulation.

  15. Tapered optical fiber tip probes based on focused ion beam-milled Fabry-Perot microcavities

    Science.gov (United States)

    André, Ricardo M.; Warren-Smith, Stephen C.; Becker, Martin; Dellith, Jan; Rothhardt, Manfred; Zibaii, M. I.; Latifi, H.; Marques, Manuel B.; Bartelt, Hartmut; Frazão, Orlando

    2016-09-01

    Focused ion beam technology is combined with dynamic chemical etching to create microcavities in tapered optical fiber tips, resulting in fiber probes for temperature and refractive index sensing. Dynamic chemical etching uses hydrofluoric acid and a syringe pump to etch standard optical fibers into cone structures called tapered fiber tips where the length, shape, and cone angle can be precisely controlled. On these tips, focused ion beam is used to mill several different types of Fabry-Perot microcavities. Two main cavity types are initially compared and then combined to form a third, complex cavity structure. In the first case, a gap is milled on the tapered fiber tip which allows the external medium to penetrate the light guiding region and thus presents sensitivity to external refractive index changes. In the second, two slots that function as mirrors are milled on the tip creating a silica cavity that is only sensitive to temperature changes. Finally, both cavities are combined on a single tapered fiber tip, resulting in a multi-cavity structure capable of discriminating between temperature and refractive index variations. This dual characterization is performed with the aid of a fast Fourier transform method to separate the contributions of each cavity and thus of temperature and refractive index. Ultimately, a tapered optical fiber tip probe with sub-standard dimensions containing a multi-cavity structure is projected, fabricated, characterized and applied as a sensing element for simultaneous temperature and refractive index discrimination.

  16. Study of the thermal effect on silicon surface induced by ion beam from plasma focus device

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Z., E-mail: pscientific5@aec.org.sy [Scientific Service Department, Atomic Energy Commission of Syria, P.O. Box: 6091, Damascus (Syrian Arab Republic); Ahmad, M. [IBA Laboratory, Atomic Energy Commission of Syria, P.O. Box: 6091, Damascus (Syrian Arab Republic); Chemistry Department, Atomic Energy Commission of Syria, P.O. Box: 6091, Damascus (Syrian Arab Republic); Al-Hawat, Sh.; Akel, M. [Physics Department, Atomic Energy Commission of Syria, P.O. Box: 6091, Damascus (Syrian Arab Republic)

    2017-04-01

    Structural modifications in form of ripples and cracks are induced by nitrogen ions from plasma focus on silicon surface. The investigation of such structures reveals correlation between ripples and cracks formation in peripheral region of the melt spot. The reason of such correlation and structure formation is explained as result of thermal effect. Melting and resolidification of the center of irradiated area occur within one micro second of time. This is supported by a numerical simulation used to investigate the thermal effect induced by the plasma focus ion beams on the silicon surface. This simulation provides information about the temperature profile as well as the dynamic of the thermal propagation in depth and lateral directions. In accordance with the experimental observations, that ripples are formed in latter stage after the arrival of last ion, the simulation shows that the thermal relaxation takes place in few microseconds after the end of the ion beam arrival. Additionally, the dependency of thermal propagation and relaxation on the distance of the silicon surface from the anode is presented.

  17. Enhanced relativistic self-focusing of Hermite-cosh-Gaussian laser beam in plasma under density transition

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, Vikas; Kant, Niti, E-mail: nitikant@yahoo.com [Department of Physics, Lovely Professional University, Phagwara 144411, Punjab (India)

    2014-04-15

    Enhanced and early relativistic self-focusing of Hermite-cosh-Gaussian (HChG) beam in the plasmas under density transition has been investigated theoretically using Wentzel-Kramers-Brillouin and paraxial ray approximation for mode indices m=0, 1, and 2. The variation of beam width parameter with normalized propagation distance for m=0, 1, and 2 is reported, and it is observed that strong self-focusing occurs as the HChG beam propagates deeper inside the nonlinear medium as spot size shrinks due to highly dense plasmas and the results are presented graphically. A comparative study between self-focusing of HChG beam in the presence and absence of plasmas density transition is reported. The dependency of beam width parameter on the normalized propagation distance for different values of decentered parameter “b” has also been presented graphically. For m=0 and 1, strong self-focusing is reported for b=1.8, and for m=2 and b=1.8, beam gets diffracted. The results obtained indicate the dependency of the self-focusing of the HChG beam on the selected values of decentered parameter. Moreover, proper selection of decentered parameter results strong self-focusing of HChG beam. Stronger self-focusing of laser beam is observed due to the presence of plasma density transition which might be very useful in the applications like the generation of inertial fusion energy driven by lasers, laser driven accelerators, etc.

  18. Effects of relativistic and channel focusing on q-Gaussian laser beam propagating in a preformed parabolic plasma channel

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Li; Hong, Xue-Ren, E-mail: hxr_nwnu@163.com; Sun, Jian-An, E-mail: sunja@nwnu.edu.cn; Tang, Rong-An; Yang, Yang; Zhou, Wei-Jun; Tian, Jian-Min; Duan, Wen-Shan

    2017-07-12

    The propagation of q-Gaussian laser beam in a preformed plasma channel is investigated by means of the variational method. A differential equation for the spot size has been obtained by including the effects of relativistic self-focusing, ponderomotive self-channeling and preformed channel focusing. The propagation behaviors and their corresponding physical conditions are identified. The comparison of the propagation between q-Gaussian and Gaussian laser beams is done by theoretical and numerical analysis. It is shown that, in the same channel, the focusing power of q-Gaussian laser beam is lower than that of Gaussian laser beam, i.e., the q-Gaussian laser beam is easier to focus than Gaussian laser beam. - Highlights: • Some behaviors for Gaussian laser are also found for q-Gaussian one. • The parameter regions corresponding to different laser behaviors are given. • Influence of q on the laser propagation behavior is obvious. • The q-Gaussian laser beam is easier to focus than the Gaussian one.

  19. Theoretical and experimental study of ions focusing systems in order to improve the ions beam brightness by suppressing aberration causes

    International Nuclear Information System (INIS)

    Faure, J.

    1966-01-01

    It is shown that a beam brightness can be improved by an order of magnitude when the sources of aberrations are suppressed in the anode region source, as well as in the extraction region and in the electrostatic focusing system. A calculation was first set up to determine a simple focusing system. The aberration ratio due to this focusing system is smaller than 10 to 15 per cent. The experimental study was developed by using an ion source and its extraction system capable of producing an aberration free beam at an energy of 20 keV and an accelerating unit up to 190 keV that confirms that the qualities of a 35 mA beam produced by the said ion source are not spoiled when the beam goes through the focusing and accelerating system that was designed to be aberration free. (author) [fr

  20. Investigation of Generation, Acceleration, Transport and Final Focusing of High-Intensity Heavy Ion Beams from Sources to Targets

    Energy Technology Data Exchange (ETDEWEB)

    Chiping Chen

    2006-10-26

    Under the auspices of the research grant, the Intense Beam Theoretical Research Goup at Massachusetts Institute of Technology's Plasma Science and Fusion Center made significant contributions in a number of important areas in the HIF and HEDP research, including: (a) Derivation of rms envelope equations and study of rms envelope dynamics for high-intensity heavy ion beams in a small-aperture AG focusing transport systems; (b) Identification of a new mechanism for chaotic particle motion, halo formation, and beam loss in high-intensity heavy ion beams in a small-aperture AG focusing systems; Development of elliptic beam theory; (d) Study of Physics Issues in the Neutralization Transport Experiment (NTX).

  1. Investigation of Generation, Acceleration, Transport and Final Focusing of High-Intensity Heavy Ion Beams from Sources to Targets

    International Nuclear Information System (INIS)

    Chiping Chen

    2006-01-01

    Under the auspices of the research grant, the Intense Beam Theoretical Research Group at Massachusetts Institute of Technology's Plasma Science and Fusion Center made significant contributions in a number of important areas in the HIF and HEDP research, including: (a) Derivation of rms envelope equations and study of rms envelope dynamics for high-intensity heavy ion beams in a small-aperture AG focusing transport systems; (b) Identification of a new mechanism for chaotic particle motion, halo formation, and beam loss in high-intensity heavy ion beams in a small-aperture AG focusing systems; (c) Development of elliptic beam theory; and (d) Study of Physics Issues in the Neutralization Transport Experiment (NTX)

  2. Nanoparticle-Assisted Scanning Focusing X-Ray Therapy with Needle Beam X Rays.

    Science.gov (United States)

    Davidson, R Andrew; Guo, Ting

    2016-01-01

    In this work, we show a new therapeutic approach using 40-120 keV X rays to deliver a radiation dose at the isocenter located many centimeters below the skin surface several hundred times greater than at the skin and how this dose enhancement can be augmented with nanomaterials to create several thousand-fold total dose enhancement effect. This novel approach employs a needle X-ray beam directed at the isocenter centimeters deep in the body while continuously scanning the beam to cover a large solid angle without overlapping at the skin. A Monte Carlo method was developed to simulate an X-ray dose delivered to the isocenter filled with X-ray absorbing and catalytic nanoparticles in a water phantom. An experimental apparatus consisting of a moving plastic phantom irradiated with a stationary 1 mm needle X-ray beam was built to test the theoretical predictions. X-ray films were used to characterize the dose profiles of the scanning X-ray apparatus. Through this work, it was determined that the X-ray dose delivered to the isocenter in a treatment voxel (t-voxel) underneath a 5 cm deep high-density polyethylene (HDPE) phantom was 295 ± 48 times greater than the surface dose. This measured value was in good agreement with the theoretical predicted value of 339-fold. Adding X-ray-absorbing nanoparticles, catalytic nanoparticles or both into the t-voxel can further augment the dose enhancement. For example, we predicted that adding 1 weight percentage (wp) of gold into water could increase the effective dose delivered to the target by onefold. Dose enhancement using 1 mm X-ray beam could reach about 1,600-fold in the t-voxel when 7.5 wp of 88 nm diameter silica-covered gold nanoparticles were added, which we showed in a previously published study can create a dose enhancement of 5.5 ± 0.46-fold without scanning focusing enhancement. Based on the experimental data from that study, mixing 0.02 wp 2.5 nm diameter small tetrakis hydroxymethyl phosphonium chloride (THPC

  3. Ion beam emission within a low energy focus plasma (0.1 kJ) operating with hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    El-Aragi, Gamal E. [Nuclear Research Center, Cairo (Egypt). Plasma Physics and Nuclear Fusion Dept.

    2010-06-15

    An investigation of energetic ion beam emission from a low energy plasma focus (0.1 kJ Mather type) device operating with hydrogen gas is studied. The ion beam emission is investigated using time-integrated and time-resolved detectors. The present plasma focus device is powered by a capacitor bank of 1 {mu}F at 18 kV maximum charging voltage. The correlation of ion beam intensity with filling gas pressure indicates that the beam emission is maximized at the optimum pressure for the focus formation at peak current. Energy of ions is determined with a time-of-flight (TOF) method, taking into account distance from the center electrode to the detection plane. (orig.)

  4. Modern Focused-Ion-Beam-Based Site-Specific Specimen Preparation for Atom Probe Tomography.

    Science.gov (United States)

    Prosa, Ty J; Larson, David J

    2017-04-01

    Approximately 30 years after the first use of focused ion beam (FIB) instruments to prepare atom probe tomography specimens, this technique has grown to be used by hundreds of researchers around the world. This past decade has seen tremendous advances in atom probe applications, enabled by the continued development of FIB-based specimen preparation methodologies. In this work, we provide a short review of the origin of the FIB method and the standard methods used today for lift-out and sharpening, using the annular milling method as applied to atom probe tomography specimens. Key steps for enabling correlative analysis with transmission electron-beam backscatter diffraction, transmission electron microscopy, and atom probe tomography are presented, and strategies for preparing specimens for modern microelectronic device structures are reviewed and discussed in detail. Examples are used for discussion of the steps for each of these methods. We conclude with examples of the challenges presented by complex topologies such as nanowires, nanoparticles, and organic materials.

  5. Plasma focus neutron anisotropy measurements and influence of a deuteron beam obstacle

    Energy Technology Data Exchange (ETDEWEB)

    Talebitaher, A. [Physics Department, University of Regina, Saskatchewan, Canada S4S 0A2 (Canada); Springham, S.V., E-mail: stuart.springham@nie.edu.sg [Natural Sciences and Science Education, National Institute of Education, 637616 (Singapore); Rawat, R.S.; Lee, P. [Natural Sciences and Science Education, National Institute of Education, 637616 (Singapore)

    2017-03-11

    The deuterium-deuterium (DD) fusion neutron yield and anisotropy were measured on a shot-to-shot basis for the NX2 plasma focus (PF) device using two beryllium fast-neutron activation detectors at 0° and 90° to the PF axis. Measurements were performed for deuterium gas pressures in the range 6–16 mbar, and positive correlations between neutron yield and anisotropy were observed at all pressures. Subsequently, at one deuterium gas pressure (13 mbar), the contribution to the fusion yield produced by the forwardly-directed D{sup +} ion beam, emitted from the plasma pinch, was investigated by using a circular Pyrex plate to obstruct the beam and suppress its fusion contribution. Neutron measurements were performed with the obstacle positioned at two distances from the anode tip, and also without the obstacle. It was found that ~ 80% of the neutron yield originates in the plasma pinch column and just above that. In addition, proton pinhole imaging was performed from the 0° and 90° directions to the pinch. The obtained proton images are consistent with the conclusion that DD fusion is concentrated (~ 80%) in the pinch column region.

  6. In situ growth optimization in focused electron-beam induced deposition

    Directory of Open Access Journals (Sweden)

    Paul M. Weirich

    2013-12-01

    Full Text Available We present the application of an evolutionary genetic algorithm for the in situ optimization of nanostructures that are prepared by focused electron-beam-induced deposition (FEBID. It allows us to tune the properties of the deposits towards the highest conductivity by using the time gradient of the measured in situ rate of change of conductance as the fitness parameter for the algorithm. The effectiveness of the procedure is presented for the precursor W(CO6 as well as for post-treatment of Pt–C deposits, which were obtained by the dissociation of MeCpPt(Me3. For W(CO6-based structures an increase of conductivity by one order of magnitude can be achieved, whereas the effect for MeCpPt(Me3 is largely suppressed. The presented technique can be applied to all beam-induced deposition processes and has great potential for a further optimization or tuning of parameters for nanostructures that are prepared by FEBID or related techniques.

  7. Investigation of beam deflection reduction and multi-beamlet focus at a large-area negative ion source for a neutral beam injector with 3-D beam trajectory simulation

    CERN Document Server

    Tanaka, M; Asano, E; Oka, Y; Osakabe, M; Tsumori, K; Kaneko, O; Yamashita, Y

    2000-01-01

    We investigated the reduction of ion beam deflection caused by electron deflection magnets, and focus of multi-beamlets at a large-area negative ion source of a neutral beam injector (NBI) in order to reduce beam loss during long-distance beam transport (>10 m) and beam injection into a nuclear fusion device. The electrostatic lens effect by displacement of the beam extraction aperture of a grounded grid (GG) was utilized for the beam deflection reduction and the multi-beamlet focus. We proposed an analysis process to adjust the aperture displacement which avoids beam collision with the GG by too much displacement. The analysis process includes a 3-D beam trajectory simulation used for analyzing the beam deflection angle and beam radius as well as theoretical calculations, which are used to calculate the aperture displacement based on the 3-D simulation results. Applicability of the analysis process was examined for a large-area high-current H sup - ion source of an NBI (0.25 mx1.25 m, 40 A, 180 keV). The ana...

  8. Determination of the sequence of intersecting lines using Focused Ion Beam/Scanning Electron Microscope.

    Science.gov (United States)

    Kim, Jiye; Kim, MinJung; An, JinWook; Kim, Yunje

    2016-05-01

    The aim of this study was to verify that the combination of focused ion beam (FIB) and scanning electron microscope/energy-dispersive X-ray (SEM/EDX) could be applied to determine the sequence of line crossings. The samples were transferred into FIB/SEM for FIB milling and an imaging operation. EDX was able to explore the chemical components and the corresponding elemental distribution in the intersection. The technique was successful in determining the sequence of heterogeneous line intersections produced using gel pens and red sealing ink with highest success rate (100% correctness). These observations show that the FIB/SEM was the appropriate instrument for an overall examination of document. © 2016 American Academy of Forensic Sciences.

  9. Nanoelectromechanical device fabrications by 3-D nanotechnology using focused-ion beams

    Directory of Open Access Journals (Sweden)

    Reo Kometani and Sunao Ishihara

    2009-01-01

    Full Text Available Nanoelectromechanical devices, which can be used as nanotools in nanofactories, were fabricated by focused ion beam chemical vapor deposition (FIB-CVD. The devices are made of diamond-like carbon (DLC, deposited on a Si substrate using gasified phenanthrene (C14H10 as a carbon source. The Young modulus and density of the deposited DLC were measured as 190 GPa and 3.8 g cm−3, respectively. The work function was smaller for DLC (2.9 eV than for W (4.7 eV and Fe (5.2 eV deposited by FIB-CVD. A nanomanipulator was manufactured by FIB-CVD and used for actual manipulations. A glass capillary based local field emitter was developed and produced as a tool for spot deposition, and its electron field emission was confirmed. FIB-CVD is proven as an efficient fabrication technology of novel nanoelectromechanical devices.

  10. Heavy charged particle radiobiology: using enhanced biological effectiveness and improved beam focusing to advance cancer therapy.

    Science.gov (United States)

    Allen, Christopher; Borak, Thomas B; Tsujii, Hirohiko; Nickoloff, Jac A

    2011-06-03

    Ionizing radiation causes many types of DNA damage, including base damage and single- and double-strand breaks. Photons, including X-rays and γ-rays, are the most widely used type of ionizing radiation in radiobiology experiments, and in radiation cancer therapy. Charged particles, including protons and carbon ions, are seeing increased use as an alternative therapeutic modality. Although the facilities needed to produce high energy charged particle beams are more costly than photon facilities, particle therapy has shown improved cancer survival rates, reflecting more highly focused dose distributions and more severe DNA damage to tumor cells. Despite early successes of charged particle radiotherapy, there is room for further improvement, and much remains to be learned about normal and cancer cell responses to charged particle radiation. 2011 Elsevier B.V. All rights reserved.

  11. Exploration of the ultimate patterning potential achievable with focused ion beams

    International Nuclear Information System (INIS)

    Gierak, J.; Bourhis, E.; Faini, G.; Patriarche, G.; Madouri, A.; Jede, R.; Bruchhaus, L.; Bauerdick, S.; Schiedt, B.; Biance, A.L.; Auvray, L.

    2009-01-01

    Decisive advances in the field of nanosciences and nanotechnologies are intimately related to the development of new instruments and of related writing schemes and methodologies. Therefore we have recently proposed the exploitation of the nano-structuring potential of a highly focused ion beam (FIB) as a tool, to overcome intrinsic limitations of current nano-fabrication techniques and to allow innovative patterning schemes that are urgently needed in many nanoscience challenges. In this work, we will first detail a very high-resolution FIB instrument we have developed specifically to meet these nano-fabrication requirements. Then we will introduce and illustrate an advanced FIB processing scheme that is the fabrication of artificial nanopores.

  12. The role of electron-stimulated desorption in focused electron beam induced deposition

    DEFF Research Database (Denmark)

    van Dorp, Willem F.; Hansen, Thomas Willum; Wagner, Jakob Birkedal

    2013-01-01

    We present the results of our study about the deposition rate of focused electron beam induced processing (FEBIP) as a function of the substrate temperature with the substrate being an electron-transparent amorphous carbon membrane. When W(CO)6 is used as a precursor it is observed that the growth...... experiments compared to literature values is consistent with earlier findings by other authors. The discrepancy is attributed to electron-stimulated desorption, which is known to occur during electron irradiation. The data suggest that, of the W(CO)6 molecules that are affected by the electron irradiation......, the majority desorbs from the surface rather than dissociates to contribute to the deposit. It is important to take this into account during FEBIP experiments, for instance when determining fundamental process parameters such as the activation energy for desorption....

  13. Bulk focused ion beam fabrication with three-dimensional shape control of nanoelectromechanical systems

    International Nuclear Information System (INIS)

    Vick, D; Sauer, V; Freeman, M R; Hiebert, W K; Fraser, A E

    2010-01-01

    Although focused ion beam (FIB) milling has previously been used for fabrication of compliant nanostructures and devices, few instances of FIB nanomachining of such devices out of bulk materials have been reported. We use FIB to fabricate nanoelectromechanical systems (NEMS) devices out of bulk materials. Ion impingement from multiple directions allows sculpting with considerable three-dimensional control of device shape, including tapering and notching. Finite-element modeling of device frequencies agrees with optical interferometric measurements, including for the effect of a localized notch. We envision that bulk FIB fabrication will be useful for NEMS prototyping, milling of tough-to-machine materials and generalized nanostructure fabrication with three-dimensional shape control

  14. Material interface detection based on secondary electron images for focused ion beam machining.

    Science.gov (United States)

    Joe, Hang-Eun; Lee, Won-Sup; Jun, Martin B G; Park, No-Cheol; Min, Byung-Kwon

    2018-01-01

    A method for interface detection is proposed for focused ion beam (FIB) processes of multilayered targets. As multilayers have emerged as promising structures for nanodevices, the FIB machining of multilayers has become a challenging issue. We proposed material interface detection by monitoring secondary electron (SE) images captured during the FIB process. The average of the gray-levels and the skewness coefficient of gray-level histograms of the SE images were evaluated to recognize endpoints for the FIB processes. The FIB process control with the proposed method was demonstrated by fabricating the nanostructures on the multilayered target without thickness information. It was also demonstrated on a curved surface. Grooves with a desired depth into the target and an aperture as an opening window were precisely fabricated by the FIB process control. The proposed strategy of the FIB process can be used for complex substrates such as curved or flexible targets. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2012-01-01

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

  16. First evidence of tyre debris characterization at the nanoscale by focused ion beam

    International Nuclear Information System (INIS)

    Milani, M.; Pucillo, F.P.; Ballerini, M.; Camatini, M.; Gualtieri, M.; Martino, S.

    2004-01-01

    In this paper, we present a novel technique for the nanoscale characterization of the outer and inner structure of tyre debris. Tyre debris is produced by the normal wear of tyres. In previous studies, the microcharacterization and identification were performed by analytical electron microscopy. This study is a development of the characterization of surface and microstructure of tyre debris. For the first time, tyre debris was analysed by focused ion beam (FIB), a technique with 2- to 5-nm resolution that does not require any sample preparation. We studied tyre debris produced in the laboratory. We made electron and ionic imaging of the surface of the material, and after a ionic cut, we studied the internal microstructure of the same sample. The tyre debris was analysed by FIB without any sample preparations unlike the case of scanning and transmission electron microscopy (SEM and TEM). Useful information was derived to improve detection and monitoring techniques of pollution by tyre degradation processes

  17. Membrane Thickness Dependence of Nanopore Formation with a Focused Helium Ion Beam

    Directory of Open Access Journals (Sweden)

    Furat Sawafta

    2014-05-01

    Full Text Available Solid-state nanopores are emerging as a valuable tool for the detection and characterization of individual biomolecules. Central to their success is the realization of fabrication strategies that are both rapid and flexible in their ability to achieve diverse device dimensions. In this paper, we demonstrate the membrane thickness dependence of solid-state nanopore formation with a focused helium ion beam. We vary membrane thickness in situ and show that the rate of pore expansion follows a reproducible trend under all investigated membrane conditions. We show that this trend shifts to lower ion dose for thin membranes in a manner that can be described quantitatively, allowing devices of arbitrary dimension to be realized. Finally, we demonstrate that thin, small-diameter nanopores formed with our approach can be utilized for high signal-to-noise ratio resistive pulse sensing of DNA.

  18. Direct fabrication of nano-gap electrodes by focused ion beam etching

    International Nuclear Information System (INIS)

    Nagase, Takashi; Gamo, Kenji; Kubota, Tohru; Mashiko, Shinro

    2006-01-01

    A simple approach to increase the reliability of nano-gap electrode fabrication techniques is presented. The method is based on maskless sputter etching of Au electrodes using a focused ion beam (FIB) and in-situ monitoring of the etching steps by measuring a current fed to the Au electrodes. The in-situ monitoring is crucial to form nano-gaps much narrower than a FIB spot size. By using this approach, gaps of ∼3-6 nm are fabricated with the high yield of ∼90%, and most of the fabricated nano-gap electrodes showed high resistances of 10 GΩ-1 TΩ. The controllability of the fabrication steps is significantly improved by using triple-layered films consisting of top Ti, Au, and bottom adhesion Ti layers. The applicability of the fabricated nano-gap electrodes to electron transport studies of nano-sized objects is demonstrated by electrical measurement of Au colloidal nano-particles

  19. Focused ion beam milling of nanocavities in single colloidal particles and self-assembled opals

    International Nuclear Information System (INIS)

    Woldering, Leon A; Otter, A M; Husken, Bart H; Vos, Willem L

    2006-01-01

    We present a new method of realizing single nanocavities in individual colloidal particles on the surface of silicon dioxide artificial opals using a focused ion beam milling technique. We show that both the radius and the position of the nanocavity can be controlled with nanometre precision, to radii as small as 40 nm. The relation between the defect size and the milling time has been established. We confirmed that milling not only occurs on the surface of the spheres, but into and through them as well. We also show that an array of nanocavities can be fashioned. Structurally modified colloids have interesting potential applications in nanolithography, as well as in chemical sensing and solar cells, and as photonic crystal cavities

  20. Visible microactuation of a ferromagnetic shape memory alloy by focused laser beam

    International Nuclear Information System (INIS)

    Hu, Zhibin; Tamang, Rajesh; Varghese, Binni; Sow, Chorng-Haur; Rajini Kanth, B; Mukhopadhyay, P K

    2012-01-01

    We used a focused laser beam to achieve large amplitude and localized controlled actuation in a microstructure made of a ferromagnetic shape memory alloy. Significant deformation (18 µm) was achieved at low laser power (20 mW) and the amplitude of actuation could be linearly controlled with the laser power. The rapid mechanical actuation shows no apparent sign of fatigue even after a million continuous oscillatory cycles. As a possible mechanism, we propose that the deformation of structure was induced by a combination of the thermal effect and the magnetic field of the incident laser light. This is possibly the first such reported visual evidence of microactuation of materials due to the optomagnetic field. (fast track communication)

  1. MgB2 junctions and SQUIDs fabricated by focused ion beam

    International Nuclear Information System (INIS)

    Burnell, G; Kang, D-J; Ansell, D A; Lee, H N; Moon, S H; Oh, B; Tarte, E J; Blamire, M G

    2003-01-01

    We have recently developed a technique for fabricating SNS junctions in MgB 2 thin films using a focused ion beam. These junctions show a strong modulation of the critical current by applied magnetic field and microwaves. They also show large I c R N products in excess of 1 mV at 4.2 K making them attractive candidates for a range of superconducting electronics applications. We have made SQUIDs with directly coupled pick-up loops using this technique which show large voltage modulations (175 μV at 10 K) and noise comparable to HTS SQUIDs. Here we will present an overview of our devices along with our latest results

  2. Effective implantation of light emitting centers by plasma immersion ion implantation and focused ion beam methods into nanosized diamond

    International Nuclear Information System (INIS)

    Himics, L.; Tóth, S.; Veres, M.; Tóth, A.; Koós, M.

    2015-01-01

    Highlights: • Characteristics of nitrogen implantation of nanodiamond using two low ion energy ion implantation methods were compared. • Formation of complex nitrogen-related defect centers was promoted by subsequent helium implantation and heat treatments. • Depth profiles of the implanted ions and the generated vacancies were determined using SRIM calculations. • The presence of nitrogen impurity was demonstrated by Fourier-transform infrared spectroscopic measurements. • A new nitrogen related band was detected in the photoluminescence spectrum of the implanted samples that was attributed to the N3 color center in nanodiamond. - Abstract: Two different implantation techniques, plasma immersion ion implantation and focused ion beam, were used to introduce nitrogen ions into detonation nanodiamond crystals with the aim to create nitrogen-vacancy related optically active centers of light emission in near UV region. Previously samples were subjected to a defect creation process by helium irradiation in both cases. Heat treatments at different temperatures (750 °C, 450 °C) were applied in order to initiate the formation of nitrogen-vacancy related complex centers and to decrease the sp 2 carbon content formed under different treatments. As a result, a relatively narrow and intensive emission band with fine structure at 2.98, 2.83 and 2.71 eV photon energies was observed in the light emission spectrum. It was assigned to the N3 complex defect center. The formation of this defect center can be expected by taking into account the relatively high dose of implanted nitrogen ions and the overlapped depth distribution of vacancies and nitrogen. The calculated depth profiles distribution for both implanted nitrogen and helium by SRIM simulation support this expectation

  3. Enhanced collective focusing of intense neutralized ion beam pulses in the presence of weak solenoidal magnetic fields

    International Nuclear Information System (INIS)

    Dorf, Mikhail A.; Davidson, Ronald C.; Kaganovich, Igor D.; Startsev, Edward A.

    2012-01-01

    The design of ion drivers for warm dense matter and high energy density physics applications and heavy ion fusion involves transverse focusing and longitudinal compression of intense ion beams to a small spot size on the target. To facilitate the process, the compression occurs in a long drift section filled with a dense background plasma, which neutralizes the intense beam self-fields. Typically, the ion bunch charge is better neutralized than its current, and as a result a net self-pinching (magnetic) force is produced. The self-pinching effect is of particular practical importance, and is used in various ion driver designs in order to control the transverse beam envelope. In the present work we demonstrate that this radial self-focusing force can be significantly enhanced if a weak (B ∼ 100 G) solenoidal magnetic field is applied inside the neutralized drift section, thus allowing for substantially improved transport. It is shown that in contrast to magnetic self-pinching, the enhanced collective self-focusing has a radial electric field component and occurs as a result of the overcompensation of the beam charge by plasma electrons, whereas the beam current becomes well-neutralized. As the beam leaves the neutralizing drift section, additional transverse focusing can be applied. For instance, in the neutralized drift compression experiments (NDCX) a strong (several Tesla) final focus solenoid is used for this purpose. In the present analysis we propose that the tight final focus in the NDCX experiments may possibly be achieved by using a much weaker (few hundred Gauss) magnetic lens, provided the ion beam carries an equal amount of co-moving neutralizing electrons from the preceding drift section into the lens. In this case the enhanced focusing is provided by the collective electron dynamics strongly affected by a weak applied magnetic field.

  4. Relativistic self-focusing of intense laser beam in thermal collisionless quantum plasma with ramped density profile

    Directory of Open Access Journals (Sweden)

    S. Zare

    2015-04-01

    Full Text Available Propagation of a Gaussian x-ray laser beam has been analyzed in collisionless thermal quantum plasma with considering a ramped density profile. In this density profile due to the increase in the plasma density, an earlier and stronger self-focusing effect is noticed where the beam width oscillates with higher frequency and less amplitude. Moreover, the effect of the density profile slope and the initial plasma density on the laser propagation has been studied. It is found that, by increasing the initial density and the ramp slope, the laser beam focuses faster with less oscillation amplitude, smaller laser spot size and more oscillations. Furthermore, a comparison is made among the laser self-focusing in thermal quantum plasma, cold quantum plasma and classical plasma. It is realized that the laser self-focusing in the quantum plasma becomes stronger in comparison with the classical regime.

  5. Nano-Tomography of Porous Geological Materials Using Focused Ion Beam-Scanning Electron Microscopy

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2016-10-01

    Full Text Available Tomographic analysis using focused ion beam-scanning electron microscopy (FIB-SEM provides three-dimensional information about solid materials with a resolution of a few nanometres and thus bridges the gap between X-ray and transmission electron microscopic tomography techniques. This contribution serves as an introduction and overview of FIB-SEM tomography applied to porous materials. Using two different porous Earth materials, a diatomite specimen, and an experimentally produced amorphous silica layer on olivine, we discuss the experimental setup of FIB-SEM tomography. We then focus on image processing procedures, including image alignment, correction, and segmentation to finally result in a three-dimensional, quantified pore network representation of the two example materials. To each image processing step we consider potential issues, such as imaging the back of pore walls, and the generation of image artefacts through the application of processing algorithms. We conclude that there is no single image processing recipe; processing steps need to be decided on a case-by-case study.

  6. Three-dimensional focus of attention for iterative cone-beam micro-CT reconstruction

    International Nuclear Information System (INIS)

    Benson, T M; Gregor, J

    2006-01-01

    Three-dimensional iterative reconstruction of high-resolution, circular orbit cone-beam x-ray CT data is often considered impractical due to the demand for vast amounts of computer cycles and associated memory. In this paper, we show that the computational burden can be reduced by limiting the reconstruction to a small, well-defined portion of the image volume. We first discuss using the support region defined by the set of voxels covered by all of the projection views. We then present a data-driven preprocessing technique called focus of attention that heuristically separates both image and projection data into object and background before reconstruction, thereby further reducing the reconstruction region of interest. We present experimental results for both methods based on mouse data and a parallelized implementation of the SIRT algorithm. The computational savings associated with the support region are substantial. However, the results for focus of attention are even more impressive in that only about one quarter of the computer cycles and memory are needed compared with reconstruction of the entire image volume. The image quality is not compromised by either method

  7. Focused-ion-beam induced interfacial intermixing of magnetic bilayers for nanoscale control of magnetic properties

    International Nuclear Information System (INIS)

    Burn, D M; Atkinson, D; Hase, T P A

    2014-01-01

    Modification of the magnetic properties in a thin-film ferromagnetic/non-magnetic bilayer system by low-dose focused ion-beam (FIB) induced intermixing is demonstrated. The highly localized capability of FIB may be used to locally control magnetic behaviour at the nanoscale. The magnetic, electronic and structural properties of NiFe/Au bilayers were investigated as a function of the interfacial structure that was actively modified using focused Ga + ion irradiation. Experimental work used MOKE, SQUID, XMCD as well as magnetoresistance measurements to determine the magnetic behavior and grazing incidence x-ray reflectivity to elucidate the interfacial structure. Interfacial intermixing, induced by low-dose irradiation, is shown to lead to complex changes in the magnetic behavior that are associated with monotonic structural evolution of the interface. This behavior may be explained by changes in the local atomic environment within the interface region resulting in a combination of processes including the loss of moment on Ni and Fe, an induced moment on Au and modifications to the spin-orbit coupling between Au and NiFe. (paper)

  8. Performance of a shallow-focus applied-magnetic-field diode for ion-beam-transport experiments

    Energy Technology Data Exchange (ETDEWEB)

    Young, F.C.; Neri, J.M.; Ottinger, P.F. [Naval Research Lab., Washington, DC (United States); Rose, D.V. [JAYCOR, Vienna (Vatican City State, Holy See); Jones, T.G.; Oliver, B.V.

    1997-12-31

    An applied-magnetic-field ion diode to study the transport of intense ion beams for light-ion inertial confinement fusion is being operated on the Gamble II generator at NRL. A Large-area (145-cm{sup 2}), shallow-focusing diode is used to provide the ion beam required for self-pinched transport (SPT) experiments. Experiments have demonstrated focusing at 70 cm for 1.2-MV, 40-kA protons. Beyond the focus, the beam hollows out consistent with 20--30 mrad microdivergence. The effect of the counter-pulse B-field on altering the ion-beam trajectories and improving the focus has been diagnosed with a multiple-pinhole-camera using radiachromic film. This diagnostic is also used to determine the radial and azimuthal uniformity of ion emission at the anode for different B-field conditions. Increasing the diode voltage to 1.5 MV and optimizing the ion current are planned before initiating SPT experiments. Experiments to measure the spatial beam profile at focus, i.e., the SPT channel entrance, are in progress. Results are presented.

  9. Simulation study on the spatial and temporal characteristics of focused microwave beam discharge in nitrogen

    Science.gov (United States)

    Yang, Wei; Zhou, Qianhong; Dong, Zhiwei

    2018-01-01

    This paper reports a simulation study on a focused microwave (frequency 9.4 GHz, pulse width 2.5 μs, and peak electric field 1.2 kV/cm) discharge in 200 Pa nitrogen. A one-dimensional (1D) fluid model is based on the wave equation for the microwave field propagating through the gas breakdown plasma, the continuity equations for electron, ion and neutral particle densities, and the energy balance equations for mean electron temperature, and nitrogen vibrational and translational temperatures. These equations are numerically solved in a self-consistent manner with a simplified plasma chemistry set, in which the reaction rates involving electrons are calculated from the electron energy distribution function (EEDF) using a two-term expansion method. The spatial and temporal characteristics of the focused microwave breakdown in nitrogen are demonstrated, which include the amplitude of the microwave electric field, and the densities and temperatures of the plasma components. The temporal evolution of the plasma electron density agrees reasonably well with that measured with a microwave interferometer. The spatial-temporal distributions of metastable states are discussed on the plasma chemistry and the character of mean electron temperature. The spatially integrated N2(C3) density shows similar trends with the measured temporal intensity of optical emission spectroscopy, except for a time delay of 100-300 ns. The quantitative discrepancies are explained in light of limitations of the 1D model with a two-term expansion of EEDF. The theoretical model is found to describe the gas breakdown plasma generated by focused microwave beams at least qualitatively.

  10. Fabrication of a free standing resolution standard for focusing MeV ion beams to sub 30 nm dimensions

    International Nuclear Information System (INIS)

    Kan, J.A. van; Shao, P.G.; Molter, P.; Saumer, M.; Bettiol, A.A.; Osipowicz, T.; Watt, F.

    2005-01-01

    With recent advances in nuclear microscopy, proton beam writing and the recent development of MeV ion nano probe facilities it is becoming increasingly important to have resolution standards with a high degree of side wall verticality. We present here a way of producing a high quality free standing resolution standards which can be used for high beam current applications like Rutherford Backscattering Spectrometry (RBS), particle induced X-ray emissions (PIXE), and low beam current applications such as secondary electron emission, scanning transmission ion microscopy (STIM) and ion beam induced current (IBIC). These standards allow rapid focusing of MeV ion beams for high resolution nuclear microscopy applications as well as proton beam writing, where knowledge of the exact beam size is vital to guarantee reproducibility in writing nanostructures. This new standard has been used to measure a one-dimensional beam profile with 1 MeV protons and gave a FWHM of 29.2 nm which is the smallest value reported for MeV protons in STIM mode

  11. Efficient tight focusing of laser beams optimally matched to their thin-film linear-to-radial polarization conversion: Method, implementation, and field near focus

    Science.gov (United States)

    Sedukhin, Andrey G.; Poleshchuk, Alexander G.

    2018-01-01

    A method is proposed for efficient, rotationally symmetric, tight mirror focusing of laser beams that is optimally matched to their thin-film linear-to-radial polarization conversion by a constant near-Brewster angle of incidence of the beams onto a polarizing element. Two optical systems and their modifications are considered that are based on this method and on the use of Toraldo filters. If focusing components of these systems operate in media with refractive indices equal to that of the focal region, they take the form of an axicon and an annular reflector generated by the revolution of an inclined parabola around the optical axis. Vectorial formulas for calculating the diffracted field near the focus of these systems are derived. Also presented are the results of designing a thin-film obliquely illuminated polarizer and a numerical simulation of deep UV laser beams generated by one of the systems and focused in an immersion liquid. The transverse and axial sizes of a needle longitudinally polarized field generated by the system with a simplest phase Toraldo filter were found to be 0.39 λ and 10.5 λ, with λ being the wavelength in the immersion liquid.

  12. Mechanism of the nanoscale localization of Ge quantum dot nucleation on focused ion beam templated Si(001) surfaces

    International Nuclear Information System (INIS)

    Portavoce, A; Kammler, M; Hull, R; Reuter, M C; Ross, F M

    2006-01-01

    We investigate the fundamental mechanism by which self-assembled Ge islands can be nucleated at specific sites on Si(001) using ultra-low-dose focused ion beam (FIB) pre-patterning. Island nucleation is controlled by a nanotopography that forms after the implantation of Ga ions during subsequent thermal annealing of the substrate. This nanotopography evolves during the annealing stage, changing from a nanoscale annular depression associated with each focused ion beam spot to a nanoscale pit, and eventually disappearing (planarizing). The correspondence of Ge quantum dot nucleation sites to the focused ion beam features requires a growth surface upon which the nanotopography is preserved. A further key observation is that the Ge wetting layer thickness is reduced in patterned regions, allowing the formation of islands on the templated regions without nucleation elsewhere. These results provide routes to the greatly enhanced design and control of quantum dot distributions and dimensions

  13. Absorption enhancement by matching the cross-section of plasmonic nanowires to the field structure of tightly focused beams.

    Science.gov (United States)

    Normatov, Alexander; Spektor, Boris; Leviatan, Yehuda; Shamir, Joseph

    2011-04-25

    Nanostructured materials, designed for enhanced light absorption, are receiving increased scientific and technological interest. In this paper we propose a physical criterion for designing the cross-sectional shape of plasmonic nanowires for improved absorption of a given tightly focused illumination. The idea is to design a shape which increases the matching between the nanowire plasmon resonance field and the incident field. As examples, we design nanowire shapes for two illumination cases: a tightly focused plane wave and a tightly focused beam containing a line singularity. We show that properly shaped and positioned silver nanowires that occupy a relatively small portion of the beam-waist area can absorb up to 65% of the total power of the incident beam.

  14. Research and development of an electron beam focusing system for a high-brightness X-ray generator.

    Science.gov (United States)

    Sakai, Takeshi; Ohsawa, Satoshi; Sakabe, Noriyoshi; Sugimura, Takashi; Ikeda, Mitsuo

    2011-01-01

    A new type of rotating anticathode X-ray generator, where an electron beam of up to 60 keV irradiates the inner surface of a U-shaped Cu anticathode, has achieved a beam brilliance of 130 kW mm(-2) (at 2.3 kW). A higher-flux electron beam is expected from simulation by optimizing the geometry of a combined-function-type magnet instead of the fringing field of the bending magnet. In order to minimize the size of the X-ray source the electron beam has been focused over a short distance by a new combined-function bending magnet, whose geometrical shape was determined by simulation using the Opera-3D, General Particle Tracer and CST-STUDIO codes. The result of the simulation clearly shows that the role of combined functions in both the bending and the steering magnets is important for focusing the beam to a small size. FWHM sizes of the beam are predicted by simulation to be 0.45 mm (horizontal) and 0.05 mm (vertical) for a 120 keV/75 mA beam, of which the effective brilliance is about 500 kW mm(-2) on the supposition of a two-dimensional Gaussian distribution. High-power tests have begun using a high-voltage 120 kV/75 mA power supply for the X-ray generator instead of 60 kV/100 mA. The beam focus size on the target will be verified in the experiments.

  15. Fabrication of oriented crystals as force measurement tips via focused ion beam and microlithography methods

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zhigang [School of Science, North University of China, Shanxi 030051 China; Chun, Jaehun [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, WA USA; Chatterjee, Sayandev [Energy and Environment Directorate, Pacific Northwest National Laboratory, WA USA; Li, Dongsheng [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, WA USA

    2017-11-09

    Detailed knowledge of the forces between nanocrystals is very crucial for understanding many generic (e.g., random aggregation/assembly and rheology) and specific (e.g., oriented attachment) phenomena at macroscopic length scales, especially considering the additional complexities involved in nanocrystals such as crystal orientation and corresponding orientation-dependent physicochemical properties. Because there are a limited number of methods to directly measure the forces, little is known about the forces that drive the various emergent phenomena. Here we report on two methods of preparing crystals as force measurement tips used in an atomic force microscope (AFM): the focused ion beam method and microlithography method. The desired crystals are fabricated using these two methods and are fixed to the AFM probe using platinum deposition, ultraviolet epoxy, or resin, which allows for the orientation-dependent force measurements. These two methods can be used to attach virtually any solid particles (from the size of a few hundreds of nanometers to millimeters). We demonstrate the force measurements between aqueous media under different conditions such as pH.

  16. Collection and focusing of laser accelerated ion beams for therapy applications

    Directory of Open Access Journals (Sweden)

    Ingo Hofmann

    2011-03-01

    Full Text Available Experimental results in laser acceleration of protons and ions and theoretical predictions that the currently achieved energies might be raised by factors 5–10 in the next few years have stimulated research exploring this new technology for oncology as a compact alternative to conventional synchrotron based accelerator technology. The emphasis of this paper is on collection and focusing of the laser produced particles by using simulation data from a specific laser acceleration model. We present a scaling law for the “chromatic emittance” of the collector—here assumed as a solenoid lens—and apply it to the particle energy and angular spectra of the simulation output. For a 10 Hz laser system we find that particle collection by a solenoid magnet well satisfies requirements of intensity and beam quality as needed for depth scanning irradiation. This includes a sufficiently large safety margin for intensity, whereas a scheme without collection—by using mere aperture collimation—hardly reaches the needed intensities.

  17. Thermal conductivity and nanocrystalline structure of platinum deposited by focused ion beam

    KAUST Repository

    Alaie, Seyedhamidreza

    2015-02-04

    Pt deposited by focused ion beam (FIB) is a common material used for attachment of nanosamples, repair of integrated circuits, and synthesis of nanostructures. Despite its common use little information is available on its thermal properties. In this work, Pt deposited by FIB is characterized thermally, structurally, and chemically. Its thermal conductivity is found to be substantially lower than the bulk value of Pt, 7.2 W m-1 K-1 versus 71.6 W m-1 K-1 at room temperature. The low thermal conductivity is attributed to the nanostructure of the material and its chemical composition. Pt deposited by FIB is shown, via aberration corrected TEM, to be a segregated mix of nanocrystalline Pt and amorphous C with Ga and O impurities. Ga impurities mainly reside in the Pt while O is homogeneously distributed throughout. The Ga impurity, small grain size of the Pt, and the amorphous carbon between grains are the cause for the low thermal conductivity of this material. Since Pt deposited by FIB is a common material for affixing samples, this information can be used to assess systematic errors in thermal characterization of different nanosamples. This application is also demonstrated by thermal characterization of two carbon nanofibers and a correction using the reported thermal properties of the Pt deposited by FIB.

  18. Three-Dimensional Nanostructure Fabrication by Focused Ion Beam Chemical Vapor Deposition

    Science.gov (United States)

    Matsui, Shinji

    In this chapter, we describe three-dimensional nanostructure fabrication using 30 keV Ga+ focused ion beam chemical vapor deposition (FIB-CVD) and a phenanthrene (C14H10) source as a precursor. We also consider microstructure plastic art, which is a new field that has been made possible by microbeam technology, and we present examples of such art, including a "micro wine glass" with an external diameter of 2.75 μm and a height of 12 μm. The film deposited during such processes is diamond-like amorphous carbon, which has a Young's modulus exceeding 600 GPa, appearing to make it highly desirable for various applications. The production of three-dimensional nanostructures is also discussed. The fabrication of microcoils, nanoelectrostatic actuators, and 0.1 μm nanowiring - all potential components of nanomechanical systems - is explained. The chapter ends by describing the realization of nanoinjectors and nanomanipulators, novel nanotools for manipulating and analyzing subcellular organelles.

  19. Thermal conductivity and nanocrystalline structure of platinum deposited by focused ion beam

    Science.gov (United States)

    Alaie, Seyedhamidreza; Goettler, Drew F.; Jiang, Ying-Bing; Abbas, Khawar; Ghasemi Baboly, Mohammadhosein; Anjum, D. H.; Chaieb, S.; Leseman, Zayd C.

    2015-02-01

    Pt deposited by focused ion beam (FIB) is a common material used for attachment of nanosamples, repair of integrated circuits, and synthesis of nanostructures. Despite its common use little information is available on its thermal properties. In this work, Pt deposited by FIB is characterized thermally, structurally, and chemically. Its thermal conductivity is found to be substantially lower than the bulk value of Pt, 7.2 W m-1 K-1 versus 71.6 W m-1 K-1 at room temperature. The low thermal conductivity is attributed to the nanostructure of the material and its chemical composition. Pt deposited by FIB is shown, via aberration corrected TEM, to be a segregated mix of nanocrystalline Pt and amorphous C with Ga and O impurities. Ga impurities mainly reside in the Pt while O is homogeneously distributed throughout. The Ga impurity, small grain size of the Pt, and the amorphous carbon between grains are the cause for the low thermal conductivity of this material. Since Pt deposited by FIB is a common material for affixing samples, this information can be used to assess systematic errors in thermal characterization of different nanosamples. This application is also demonstrated by thermal characterization of two carbon nanofibers and a correction using the reported thermal properties of the Pt deposited by FIB.

  20. Chemical tuning of PtC nanostructures fabricated via focused electron beam induced deposition

    International Nuclear Information System (INIS)

    Plank, Harald; Gspan, Christian; Kothleitner, Gerald; Hofer, Ferdinand; Haber, Thomas

    2013-01-01

    The fundamental dependence between process parameters during focused electron beam induced deposition and the chemistry of functional PtC nanostructures have been studied via a multi-technique approach using SEM, (S)TEM, EELS, AFM, and EFM. The study reveals that the highest Pt contents can only be achieved by an ideal balance between potentially dissociating electrons and available precursor molecules on the surface. For precursor regimes apart from this situation, an unwanted increase of carbon is observed which originates from completely different mechanisms: (1) an excess of electrons leads to polymerization of precursor fragments whereas (2) a lack of electrons leads to incompletely dissociated precursor molecules incorporated into the nanostructures. While the former represents an unwanted class of carbon, the latter condition maximizes the volume growth rates and allows for post-growth curing strategies which can strongly increase the functionality. Furthermore, the study gives an explanation of why growing deposits can dynamically change their chemistry and provides a straightforward guide towards more controlled fabrication conditions. (paper)

  1. submitter Light Extraction From Scintillating Crystals Enhanced by Photonic Crystal Structures Patterned by Focused Ion Beam

    CERN Document Server

    Modrzynski, Pawel; Knapitsch, Arno; Kunicki, Piotr; Lecoq, Paul; Moczala, Magdalena; Papakonstantinou, Ioannis; Auffray, Etiennette

    2016-01-01

    “Photonic Crystals (PhC)” have been used in a variety of fields as a structure for improving the light extraction efficiency from materials with high index of refraction. In previous work we already showed the light extraction improvement of several PhC covered LYSO crystals in computer simulations and practical measurements. In this work, new samples are made using different materials and techniques which allows further efficiency improvements. For rapid prototyping of PhC patterns on scintillators we tested a new method using “Focused Ion Beam (FIB)” patterning. The FIB machine is a device similar to a “Scanning Electron Microscope (SEM)”, but it uses ions (mainly gallium) instead of electrons for the imaging of the samples' surface. The additional feature of FIB devices is the option of surface patterning in nano-scale which was exploited for our samples. Three samples using FIB patterning have been produced. One of them is a direct patterning of the extraction face of a 0.8×0.8×10 $mm^3$ LYS...

  2. Feasibility of Focused Beam Reflectance Measurement (FBRM) for Analysis of Pharmaceutical Suspensions in Preclinical Development.

    Science.gov (United States)

    Dave, Kaushalkumar; Luner, Paul E; Forness, Cecile; Baker, Doris; Jankovsky, Corinne; Chen, Shirlynn

    2018-01-01

    This study examined the use of focused beam reflectance measurement (FBRM) for qualitative and quantitative analysis of pharmaceutical suspensions with particular application to toxicology supply preparations for use in preclinical studies. Aqueous suspensions of ibuprofen were used as prototype formulations. Initial experiments were conducted to examine the effects of operational conditions including FBRM probe angle, probe location, and mixing (method and rate of mixing) on the FBRM analysis. Once experimental conditions were optimized, the homogeneity and sedimentation-redispersion of particles in the suspensions were assessed. Ibuprofen suspension under continuous agitation was monitored using FBRM for 60 h to study particle size change over time. Another study was performed to determine if particle count rates obtained by FBRM could be correlated to suspension concentration. The location and the angle of the FBRM probe relative to the beaker contents, and the rate and the method of mixing the suspension were found to be sensitive parameters during FBRM analysis. FBRM was able to monitor the process of particle sedimentation in the suspension. The attrition of ibuprofen particles was detectable by FBRM during prolonged stirring with an increase in the number of smaller particles and decrease in the number of larger particles. A strong correlation was observed between particle count rate by FBRM and ibuprofen concentration in the suspension. Also, change in content uniformity in the suspension at different locations of the beaker was represented by FBRM particle count. Overall, FBRM has potential to be a useful tool for qualitative and quantitative analysis of pharmaceutical suspensions.

  3. TUTORIAL: Focused-ion-beam-based rapid prototyping of nanoscale magnetic devices

    Science.gov (United States)

    Khizroev, S.; Litvinov, D.

    2004-03-01

    In this tutorial, focused-ion-beam (FIB)-based fabrication is considered from a very unconventional angle. FIB is considered not as a fabrication tool that can be used for mass production of electronic devices, similar to optical and E-beam—based lithography, but rather as a powerful tool to rapidly fabricate individual nanoscale magnetic devices for prototyping future electronic applications. Among the effects of FIB-based fabrication of magnetic devices, the influence of Ga+-ion implantation on magnetic properties is presented. With help of magnetic force microscopy (MFM), it is shown that there is a critical doze of ions that a magnetic material can be exposed to without experiencing a change in the magnetic properties. Exploiting FIB from such an unconventional perspective is especially favourable today when the future of so many novel technologies depends on the ability to rapidly fabricate prototype nanoscale magnetic devices. As one of the most illustrative examples, the multi-billion-dollar data storage industry is analysed as the technology field that strongly benefited from implementing FIB in the above-described role. The essential role of FIB in the most recent trend of the industry towards perpendicular magnetic recording is presented. Moreover, other emerging and fast-growing technologies are considered as examples of nanoscale technologies whose future could strongly depend on the implementation of FIB in the role of a nanoscale fabrication tool for rapid prototyping. Among the other described technologies are 'ballistic' magnetoresistance, patterned magnetic media, magnetoresistive RAM (MRAM), and magnetic force microscopy.

  4. Interaction of microcracks with selected interfaces: Focused ion beam for a systematic crack initiation

    International Nuclear Information System (INIS)

    Marx, M.; Schaef, W.; Vehoff, H.; Holzapfel, C.

    2006-01-01

    The newly introduced combination of focused ion beam technique with high resolution scanning electron microscopy is the first method to initiate artificial microcracks with idealized crack parameters in front of selected phase- and grain boundaries. The boundaries of interest are selected after a complete sample characterization by Electron Back Scatter Diffraction and a calculation of the preferred slip systems within each grain. This combination of characterizing- and manipulating techniques on a microscale enables for the first time a systematic investigation of the interaction of short cracks with microstructural barriers to check the models of Tanaka, Navarro and De Los Rios quantitatively. In this paper, different notch geometries from single lines to penny shaped surface cracks for the initiation of artificial microcracks are presented. It is shown that not only the starting point of a crack can be selected. Further, the crack propagation path can be predetermined by initiating the crack directly on a slip system with a high Schmid factor. As a first result the influence of grain boundaries with different misorientation angles on the crack propagation rate for a directionally solidified nickel-based superalloy is shown. Finally this method is discussed as a powerful technique for grain boundary engineering

  5. Site-Specific Cryo-focused Ion Beam Sample Preparation Guided by 3D Correlative Microscopy.

    Science.gov (United States)

    Arnold, Jan; Mahamid, Julia; Lucic, Vladan; de Marco, Alex; Fernandez, Jose-Jesus; Laugks, Tim; Mayer, Tobias; Hyman, Anthony A; Baumeister, Wolfgang; Plitzko, Jürgen M

    2016-02-23

    The development of cryo-focused ion beam (cryo-FIB) for the thinning of frozen-hydrated biological specimens enabled cryo-electron tomography (cryo-ET) analysis in unperturbed cells and tissues. However, the volume represented within a typical FIB lamella constitutes a small fraction of the biological specimen. Retaining low-abundance and dynamic subcellular structures or macromolecular assemblies within such limited volumes requires precise targeting of the FIB milling process. In this study, we present the development of a cryo-stage allowing for spinning-disk confocal light microscopy at cryogenic temperatures and describe the incorporation of the new hardware into existing workflows for cellular sample preparation by cryo-FIB. Introduction of fiducial markers and subsequent computation of three-dimensional coordinate transformations provide correlation between light microscopy and scanning electron microscopy/FIB. The correlative approach is employed to guide the FIB milling process of vitrified cellular samples and to capture specific structures, namely fluorescently labeled lipid droplets, in lamellas that are 300 nm thick. The correlation procedure is then applied to localize the fluorescently labeled structures in the transmission electron microscopy image of the lamella. This approach can be employed to navigate the acquisition of cryo-ET data within FIB-lamellas at specific locations, unambiguously identified by fluorescence microscopy. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  6. Focused beam reflectance measurement as a tool for in situ monitoring of the lactose crystallization process.

    Science.gov (United States)

    Pandalaneni, K; Amamcharla, J K

    2016-07-01

    Lactose accounts for about 75 and 85% of the solids in whey and deproteinized whey, respectively. Production of lactose is usually carried out by a process called crystallization. Several factors including rate of cooling, presence of impurities, and mixing speed influence the crystal size characteristics. To optimize the lactose crystallization process parameters to maximize the lactose yield, it is important to monitor the crystallization process. However, efficient in situ tools to implement at concentrations relevant to the dairy industry are lacking. The objective of the present work was to use a focused beam reflectance measurement (FBRM) system for in situ monitoring of lactose crystallization at supersaturated concentrations (wt/wt) 50, 55, and 60% at 20 and 30°C. The FBRM data were compared with Brix readings collected using a refractometer during isothermal crystallization. Chord length distributions obtained from FBRM in the ranges of lactose crystallization at various concentrations and temperatures was successfully assessed in the study. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  7. Spin-resolved magnetic studies of focused ion beam etched nano-sized magnetic structures

    International Nuclear Information System (INIS)

    Li Jian; Rau, Carl

    2005-01-01

    Scanning ion microscopy with polarization analysis (SIMPA) is used to study the spin-resolved surface magnetic structure of nano-sized magnetic systems. SIMPA is utilized for in situ topographic and spin-resolved magnetic domain imaging as well as for focused ion beam (FIB) etching of desired structures in magnetic or non-magnetic systems. Ultra-thin Co films are deposited on surfaces of Si(1 0 0) substrates, and ultra-thin, tri-layered, bct Fe(1 0 0)/Mn/bct Fe(1 0 0) wedged magnetic structures are deposited on fcc Pd(1 0 0) substrates. SIMPA experiments clearly show that ion-induced electrons emitted from magnetic surfaces exhibit non-zero electron spin polarization (ESP), whereas electrons emitted from non-magnetic surfaces such as Si and Pd exhibit zero ESP, which can be used to calibrate sputtering rates in situ. We report on new, spin-resolved magnetic microstructures, such as magnetic 'C' states and magnetic vortices, found at surfaces of FIB patterned magnetic elements. It is found that FIB milling has a negligible effect on surface magnetic domain and domain wall structures. It is demonstrated that SIMPA can evolve into an important and efficient tool to study magnetic domain, domain wall and other structures as well as to perform magnetic depth profiling of magnetic nano-systems to be used in ultra-high density magnetic recording and in magnetic sensors

  8. Suspended tungsten-based nanowires with enhanced mechanical properties grown by focused ion beam induced deposition

    Science.gov (United States)

    Córdoba, Rosa; Lorenzoni, Matteo; Pablo-Navarro, Javier; Magén, César; Pérez-Murano, Francesc; María De Teresa, José

    2017-11-01

    The implementation of three-dimensional (3D) nano-objects as building blocks for the next generation of electro-mechanical, memory and sensing nano-devices is at the forefront of technology. The direct writing of functional 3D nanostructures is made feasible by using a method based on focused ion beam induced deposition (FIBID). We use this technique to grow horizontally suspended tungsten nanowires and then study their nano-mechanical properties by three-point bending method with atomic force microscopy. These measurements reveal that these nanowires exhibit a yield strength up to 12 times higher than that of the bulk tungsten, and near the theoretical value of 0.1 times the Young’s modulus (E). We find a size dependence of E that is adequately described by a core-shell model, which has been confirmed by transmission electron microscopy and compositional analysis at the nanoscale. Additionally, we show that experimental resonance frequencies of suspended nanowires (in the MHz range) are in good agreement with theoretical values. These extraordinary mechanical properties are key to designing electro-mechanically robust nanodevices based on FIBID tungsten nanowires.

  9. Thermal diffusivity measurement of focused-ion-beam fabricated sample using photothermal reflectance technique.

    Science.gov (United States)

    Hua, Zilong; Ban, Heng

    2017-05-01

    Focused-Ion-Beam (FIB) can lift-off micrometer-sized samples from bulk materials for structural characterization and property measurement. The ability to determine thermophysical properties of such samples offers unique insight into the local microstructure-property relationship. A photothermal reflectance technique is developed to measure the thermal diffusivity of FIB-fabricated, micrometer-sized samples in this study. An analytic model is established to guide the experimental design and data analysis for the limited sample size and thickness. The thermal diffusivity of the sample can be extracted from a series of spatial-scan measurements at several modulated heating frequencies. To demonstrate the viability of the technique, a FIB-fabricated SiC plate with the size of 42 μm × 31 μm × 8 μm was used to represent high conductivity materials, which pose more challenges for the technique. The result compares favorably with literature values of SiC. The measurement uncertainty is quantified and possible experimental error sources are discussed. This technique is specially promising for thermal property measurements on nuclear fuels and materials.

  10. Effect of quadrupole focusing-field fluctuation on the transverse stability of intense hadron beams in storage rings

    Science.gov (United States)

    Ito, Kiyokazu; Matsuba, Masanori; Okamoto, Hiromi

    2018-02-01

    A systematic experimental study is performed to clarify the parameter dependence of the noise-induced beam instability previously demonstrated by a Princeton group [M. Chung et al., Phys. Rev. Lett. 102, 145003 (2009)]. Because of the weakness of the driving force, the instability develops very slowly, which substantially limits the application of conventional experimental and numerical techniques. In the present study, a novel tabletop apparatus called "S-POD" (Simulator of Particle Orbit Dynamics) is employed to explore the long-term collective behavior of intense hadron beams. S-POD provides a many-body Coulomb system physically equivalent to a relativistic charged-particle beam and thus enables us to conduct various beam-dynamics experiments without the use of large-scale machines. It is reconfirmed that random noise on the linear beam-focusing potential can be a source of slow beam quality degradation. Experimental observations are explained well by a simple perturbation theory that predicts the existence of a series of dangerous noise frequency bands overlooked in the previous study. Those additional instability bands newly identified with S-POD are more important practically because the driving noise frequencies can be very low. The dependence of the instability on the noise level, operating tune, and beam intensity is examined and found consistent with theoretical predictions.

  11. Self-focusing, self modulation and stability properties of laser beam propagating in plasma: A variational approach

    International Nuclear Information System (INIS)

    Kaur, Ravinder; Gill, Tarsem Singh; Mahajan, Ranju

    2010-01-01

    Laboratory as well as Particle in cell (PIC) simulation experiments reveal the strong flow of energetic electrons co-moving with laser beam in laser plasma interaction. Equation governing the evolution of complex envelope in slowly varying envelope approximation is nonlinear parabolic equation. A Lagrangian for the problem is set up and assuming a trial Gaussian profile, we solve the reduced Lagrangian problem for beam width and curvature. Besides self-focusing and self-modulation of laser beam, we observe that stability properties of such plasma system are studied about equilibrium values using this variational approach. We obtained an eigen value equation, which is cubic in nature and investigated the criterion for stability using Hurwitz conditions for laser beam plasma system.

  12. Enhanced light trapping by focused ion beam (FIB) induced self-organized nanoripples on germanium (100) surface

    Science.gov (United States)

    Kamaliya, Bhaveshkumar; Mote, Rakesh G.; Aslam, Mohammed; Fu, Jing

    2018-03-01

    In this paper, we demonstrate enhanced light trapping by self-organized nanoripples on the germanium surface. The enhanced light trapping leading to high absorption of light is confirmed by the experimental studies as well as the numerical simulations using the finite-difference time-domain method. We used gallium ion (Ga+) focused ion beam to enable the formation of the self-organized nanoripples on the germanium (100) surface. During the fabrication, the overlap of the scanning beam is varied from zero to negative value and found to influence the orientation of the nanoripples. Evolution of nanostructures with the variation of beam overlap is investigated. Parallel, perpendicular, and randomly aligned nanoripples with respect to the scanning direction are obtained via manipulation of the scanning beam overlap. 95% broadband absorptance is measured in the visible electromagnetic region for the nanorippled germanium surface. The reported light absorption enhancement can significantly improve the efficiency of germanium-silicon based photovoltaic systems.

  13. Generation and focusing of pulsed intense ion beams. Progress report, April 1, 1979-September 30, 1979

    International Nuclear Information System (INIS)

    Sudan, R.N.; Hammer, D.A.

    1981-04-01

    Theoretical calculations suggest that an intense pulsed approx. 1 MeV proton beam can be used to simulate the characteristics of approx. 1 GeV heavy ion beam propagation in an inertial confinement fusion reactor chamber. Given the present availability of the former beams and the high projected cost for obtaining the latter ones, such experimental simulations appear appropriate. Work was undertaken under the cited contract to apply the technology of intense proton beams to this end. The first task was the development of a high brightness pulsed proton source which could produce a weakly convergent approx. 10 kA proton beam in a field free drift region. This was accomplished at approx. 250 keV, and preliminary beam propagation experiments were performed. It was concluded that a proper simulation experiment would require a higher voltage beam. An upgraded version of the existing generator, which would have produced a 30 kA beam at about 500 keV, and further propagation experiments were proposed as part of our unsuccessful renewal proposal dated October 15, 1979

  14. Effect of Higher Order Axial Electron Temperature on Self-Focusing of Electromagnetic Pulsed Beam in Collisional Plasma

    International Nuclear Information System (INIS)

    Xia Xiongping; Yi Lin

    2012-01-01

    Effect of higher order axial electron temperature on self-focusing of electromagnetic pulsed beam in collisional plasma is investigated. It is shown that higher order axial electron temperature T p4 is not trivial than T p0 and T p2 , which can modify slightly radial redistribution of electron density and increases effective dielectric constant. As a result, on one hand, slightly reduce electromagnetic beam self-focusing in the course of oscillatory convergence, on the other hand, quicken beam divergence in the course of steady divergence, i.e., higher order axial electron temperature T p4 can decrease the influence of collisional nonlinearity in collisional plasma. (physics of gases, plasmas, and electric discharges)

  15. Observation of X-ray intensity distribution from the anode of a fine-focus tube using Δω - Δ2θ scans

    International Nuclear Information System (INIS)

    Grigg, M.W.; Barnea, Z.; Maslen, V.W.

    1995-01-01

    A split intensity distribution from the anode of fine focus x-ray tubes probably due to tungsten deposited on the target is reported. Such a doubling of the target complicates the interpretation of Δ ω -Δ2θ intensity distributions and introduces systematic errors in the determination of lattice parameters. It is estimated that the increasing tungsten deposit affects, in time, the intensity of x-ray tubes. 4 refs., 4 figs

  16. Guiding and focusing of fast electron beams produced by ultra-intense laser pulse using a double cone funnel target

    International Nuclear Information System (INIS)

    Zhang, Wen-shuai; Cai, Hong-bo; Zhu, Shao-ping

    2015-01-01

    A novel double cone funnel target design aiming at efficiently guiding and focusing fast electron beams produced in high intensity (>10 19  W/cm 2 ) laser-solid interactions is investigated via two-dimensional particle-in-cell simulations. The forward-going fast electron beams are shown to be directed and focused to a smaller size in comparison with the incident laser spot size. This plasma funnel attached on the cone target guides and focuses electrons in a manner akin to the control of liquid by a plastic funnel. Such device has the potential to add substantial design flexibility and prevent inefficiencies for important applications such as fast ignition. Two reasons account for the collimation of fast electron beams. First, the sheath electric fields and quasistatic magnetic fields inside the vacuum gap of the double cone provide confinement of the fast electrons in the laser-plasma interaction region. Second, the interface magnetic fields inside the beam collimator further guide and focus the fast electrons during the transport. The application of this technique to cone-guided fast ignition is considered, and it is shown that it can enhance the laser energy deposition in the compressed fuel plasma by a factor of 2 in comparison with the single cone target case

  17. Effects of focused ion beam milling on electron backscatter diffraction patterns in strontium titanate and stabilized zirconia

    DEFF Research Database (Denmark)

    Saowadee, Nath; Agersted, Karsten; Bowen, Jacob R.

    2012-01-01

    This study investigates the effect of focused ion beam (FIB) current and accelerating voltage on electron backscatter diffraction pattern quality of yttria‐stabilized zirconia (YSZ) and Nb‐doped strontium titanate (STN) to optimize data quality and acquisition time for 3D‐EBSD experiments by FIB...

  18. Focused Beam Reflectance Measurement (FBRM) a promising tool for wet-end optimisation and web break prediction

    NARCIS (Netherlands)

    Lumpe, C.; Joore, L.; Homburg, K.; Verstraeten, E.

    2001-01-01

    The trends to increased speed and higher qualities have increased the need for wet-end control - especially for systems with on-line measuring devices and feed forward control. One possibility is the use of Focused Beam Reflectance Measurement (FBRM) to measure on-line particle counts and their

  19. Using a quantum well heterostructure to study the longitudinal and transverse electric field components of a strongly focused laser beam

    NARCIS (Netherlands)

    Kihara Rurimo, G.; Schardt, M.; Quabis, S.; Malzer, S.; Dotzler, C.; Winkler, A.; Leuchs, G.; Döhler, G.H.; Driscoll, D.; Hanson, M.; Gossard, A.C.; Pereira, S.F.

    2006-01-01

    We report a method to measure the electric energy density of longitudinal and transverse electric field components of strongly focused polarized laser beams. We used a quantum well photodetector and exploited the polarization dependent optical transitions of light holes and heavy holes to probe the

  20. Extending the detection limit of dopants for focused ion beam prepared semiconductor specimens examined by off-axis electron holography

    DEFF Research Database (Denmark)

    Cooper, David; Rivallin, Pierrette; Hartmann, Jean-Michel

    2009-01-01

    Silicon specimens containing p-n junctions have been prepared for examination by off-axis electron holography using focused ion beam (FIB) milling. FIB milling modifies the surfaces of the specimens due to gallium implantation and the creation of defects which has the effect of reducing the active...

  1. Boron nitride stamp for ultra-violet nanoimprinting lithography fabricated by focused ion beam lithography

    International Nuclear Information System (INIS)

    Altun, Ali Ozhan; Jeong, Jun-Ho; Rha, Jong-Joo; Kim, Ki-Don; Lee, Eung-Sug

    2007-01-01

    Cubic boron nitride (c-BN) is one of the hardest known materials (second after diamond). It has a high level of chemical resistance and high UV transmittance. In this study, a stamp for ultra-violet nanoimprint lithography (UV-NIL) was fabricated using a bi-layered BN film deposited on a quartz substrate. Deposition of the BN was done using RF magnetron sputtering. A hexagonal boron nitride (h-BN) layer was deposited for 30 min before c-BN was deposited for 30 min. The thickness of the film was measured as 160 nm. The phase of the c-BN layer was investigated using Fourier transform infrared (FTIR) spectrometry, and it was found that the c-BN layer has a 40% cubic phase. The deposited film was patterned using focused ion beam (FIB) lithography for use as a UV-NIL stamp. Line patterns were fabricated with the line width and line distance set at 150 and 150 nm, respectively. The patterning process was performed by applying different currents to observe the effect of the current value on the pattern profile. The fabricated patterns were investigated using AFM, and it was found that the pattern fabricated by applying a current value of 50 picoamperes (pA) has a better profile with a 65 nm line depth. The UV transmittance of the 160 nm thick film was measured to be 70-86%. The hardness and modulus of the BN was measured to be 12 and 150 GPa, respectively. The water contact angle of the stamp surface was measured at 75 0 . The stamp was applied to UV-NIL without coating with an anti-adhesion layer. Successful imprinting was proved via scanning electron microscope (SEM) images of the imprinted resin

  2. Boron nitride stamp for ultra-violet nanoimprinting lithography fabricated by focused ion beam lithography

    Energy Technology Data Exchange (ETDEWEB)

    Altun, Ali Ozhan [Nano-Mechanical Systems Research Center, Korea Institute of Machinery and Materials, 171 Jang-dong, Yuseung-gu, Daejeon 305-343 (Korea, Republic of); Jeong, Jun-Ho [Nano-Mechanical Systems Research Center, Korea Institute of Machinery and Materials, 171 Jang-dong, Yuseung-gu, Daejeon 305-343 (Korea, Republic of); Rha, Jong-Joo [Surface Technology Research Center, Korea Institute of Machinery and Materials, 66 Sangnam-Dong, Changwon-Shi, Kyungnam-Do (Korea, Republic of); Kim, Ki-Don [Nano-Mechanical Systems Research Center, Korea Institute of Machinery and Materials, 171 Jang-dong, Yuseung-gu, Daejeon 305-343 (Korea, Republic of); Lee, Eung-Sug [Nano-Mechanical Systems Research Center, Korea Institute of Machinery and Materials, 171 Jang-dong, Yuseung-gu, Daejeon 305-343 (Korea, Republic of)

    2007-11-21

    Cubic boron nitride (c-BN) is one of the hardest known materials (second after diamond). It has a high level of chemical resistance and high UV transmittance. In this study, a stamp for ultra-violet nanoimprint lithography (UV-NIL) was fabricated using a bi-layered BN film deposited on a quartz substrate. Deposition of the BN was done using RF magnetron sputtering. A hexagonal boron nitride (h-BN) layer was deposited for 30 min before c-BN was deposited for 30 min. The thickness of the film was measured as 160 nm. The phase of the c-BN layer was investigated using Fourier transform infrared (FTIR) spectrometry, and it was found that the c-BN layer has a 40% cubic phase. The deposited film was patterned using focused ion beam (FIB) lithography for use as a UV-NIL stamp. Line patterns were fabricated with the line width and line distance set at 150 and 150 nm, respectively. The patterning process was performed by applying different currents to observe the effect of the current value on the pattern profile. The fabricated patterns were investigated using AFM, and it was found that the pattern fabricated by applying a current value of 50 picoamperes (pA) has a better profile with a 65 nm line depth. The UV transmittance of the 160 nm thick film was measured to be 70-86%. The hardness and modulus of the BN was measured to be 12 and 150 GPa, respectively. The water contact angle of the stamp surface was measured at 75{sup 0}. The stamp was applied to UV-NIL without coating with an anti-adhesion layer. Successful imprinting was proved via scanning electron microscope (SEM) images of the imprinted resin.

  3. Glass nanoimprint using amorphous Ni-P mold etched by focused-ion beam

    International Nuclear Information System (INIS)

    Mekaru, Harutaka; Kitadani, Takeshi; Yamashita, Michiru; Takahashi, Masaharu

    2007-01-01

    The authors succeeded in glass-nanoimprint lithography of micropatterns and nanopatterns using an amorphous Ni-P alloy mold. Glasslike carbon has been used as a mold material to mold not only Pyrex glass but also quartz, because it is still stable at a temperature of 1650 deg. C. However, it is difficult to process glasslike carbon substrates into arbitrary shapes by machining. They thought that amorphous Ni-P alloy could be used as a mold material for industrial glass molding. If Ni is electroless plated when mixed with suitable amount of P on a Si wafer, the Ni-P alloy layer becomes amorphous. An appropriate ratio of Ni and P was determined by the results of x-ray-diffraction measurements. The optimized composition ratio of Ni-P was Ni:P=92:8 wt %. Moreover, line and space patterns and dot arrays with linewidths of as little as 500 nm were etched on the mold using focused-ion beam (FIB) and the processing accuracy for the amorphous Ni-P layer was compared with that for the pure Ni layer. The result was that patterns of 500 nm width were etched to a depth of 2 μm on an amorphous Ni-P alloy mold and the processed surfaces were smooth. In contrast, in the case of the pure Ni layer, the processing line was notched and the sidewalls were very rough. The crystal grain seems to hinder the processing of the nanopattern. After FIB etching, the amorphous Ni-P alloy was thermally treated at 400 deg. C to improve the hardness. Finally, line and space patterns and dot arrays on the amorphous Ni-P alloy mold were nanoimprinted on Pyrex glass using a glass-nanoimprint system (ASHE0201) that National Institute of Advanced Industrial Science and Technology developed

  4. 3D magnetic nanostructures grown by focused electron and ion beam induced deposition

    Science.gov (United States)

    Fernandez-Pacheco, Amalio

    Three-dimensional nanomagnetism is an emerging research area, where magnetic nanostructures extend along the whole space, presenting novel functionalities not limited to the substrate plane. The development of this field could have a revolutionary impact in fields such as electronics, the Internet of Things or bio-applications. In this contribution, I will show our recent work on 3D magnetic nanostructures grown by focused electron and ion beam induced deposition. This 3D nano-printing techniques, based on the local chemical vapor deposition of a gas via the interaction with electrons and ions, makes the fabrication of complex 3D magnetic nanostructures possible. First, I will show how by exploiting different growth regimes, suspended Cobalt nanowires with modulated diameter can be patterned, with potential as domain wall devices. Afterwards, I will show recent results where the synthesis of Iron-Gallium alloys can be exploited in the field of artificial multiferroics. Moreover, we are developing novel methodologies combining physical vapor deposition and 3D nano-printing, creating Permalloy 3D nanostrips with controllable widths and lengths up to a few microns. This approach has been extended to more complex geometries by exploiting advanced simulation growth techniques combining Monte Carlo and continuum model methods. Throughout the talk, I will show the methodology we are following to characterize 3D magnetic nanostructures, by combining magneto-optical Kerr effect, scanning probe microscopy and electron and X-R magnetic imaging, and I will highlight some of the challenges and opportunities when studying these structures. I acknowledge funding from EPSRC and the Winton Foundation.

  5. Boron nitride stamp for ultra-violet nanoimprinting lithography fabricated by focused ion beam lithography

    Science.gov (United States)

    Ozhan Altun, Ali; Jeong, Jun-Ho; Rha, Jong-Joo; Kim, Ki-Don; Lee, Eung-Sug

    2007-11-01

    Cubic boron nitride (c-BN) is one of the hardest known materials (second after diamond). It has a high level of chemical resistance and high UV transmittance. In this study, a stamp for ultra-violet nanoimprint lithography (UV-NIL) was fabricated using a bi-layered BN film deposited on a quartz substrate. Deposition of the BN was done using RF magnetron sputtering. A hexagonal boron nitride (h-BN) layer was deposited for 30 min before c-BN was deposited for 30 min. The thickness of the film was measured as 160 nm. The phase of the c-BN layer was investigated using Fourier transform infrared (FTIR) spectrometry, and it was found that the c-BN layer has a 40% cubic phase. The deposited film was patterned using focused ion beam (FIB) lithography for use as a UV-NIL stamp. Line patterns were fabricated with the line width and line distance set at 150 and 150 nm, respectively. The patterning process was performed by applying different currents to observe the effect of the current value on the pattern profile. The fabricated patterns were investigated using AFM, and it was found that the pattern fabricated by applying a current value of 50 picoamperes (pA) has a better profile with a 65 nm line depth. The UV transmittance of the 160 nm thick film was measured to be 70 86%. The hardness and modulus of the BN was measured to be 12 and 150 GPa, respectively. The water contact angle of the stamp surface was measured at 75°. The stamp was applied to UV-NIL without coating with an anti-adhesion layer. Successful imprinting was proved via scanning electron microscope (SEM) images of the imprinted resin.

  6. Study of charge-sharing in MEDIPIX3 using a micro-focused synchrotron beam

    International Nuclear Information System (INIS)

    Gimenez, E N; Horswell, I; Marchal, J; Sawhney, K J S; Tartoni, N; Ballabriga, R; Campbell, M; Llopart, X; Turecek, D

    2011-01-01

    X-ray photon-counting detectors consisting of a silicon pixel array sensor bump-bonded to a CMOS electronic readout chip offer several advantages over traditional X-ray detection technologies used for synchrotron applications. They offer high frame rate, dynamic range, count rate capability and signal-to-noise ratio. A survey of the requirements for future synchrotron detectors carried out at the Diamond Light Source synchrotron highlighted the needs for detectors with a pixel size of the order of 50μm. Reducing the pixel size leads to an increase of charge-sharing events between adjacent pixels and, therefore, to a degradation of the energy resolution and image quality of the detector. This effect was observed with MEDIPIX2, a photon-counting readout chip with a pixel size of 55μm. The latest generation of the MEDIPIX family, MEDIPIX3, is designed to overcome this charge-sharing effect in an implemented readout operating mode referred to as Charge Summing Mode. MEDIPIX3 has the same pixel size as MEDIPIX2, but it is implemented in an 8-metal 0.13μm CMOS technology which enables increased functionality per pixel. The present work focuses on the study of the charge-sharing effect when the MEDIPIX3 is operated in Charge Summing Mode compared to the conventional readout mode, referred to as Single Pixel Mode. Tests of a standard silicon photodiode array bump-bonded to MEDIPIX3 were performed in beamline B16 at the Diamond Light Source synchrotron. A monochromatic micro-focused beam of 2.9μm x 2.2μm size at 15keV was used to scan a cluster of nine pixels in order to study the charge collection and X-ray count allocation process for each readout mode, Single Pixel Mode and Charge Summing Mode. The study showed that charge-shared events were eliminated when Medipix3 was operated in Charge Summing Mode.

  7. Transport of long-pulse relativistic electron beams in preformed plasma channels in the ion focus regime

    International Nuclear Information System (INIS)

    Miller, J.D.

    1989-01-01

    Experiments have been performed demonstrating efficient transport of long-pulse (380 ns), high-current (200 A), relativistic electron beams (REBs) in preformed plasma channels in the ion focus regime (IFR). Plasma channels were created by low-energy ( e , and channel ion mass, in agreement with theoretical values predicted for the ion hose instability. Microwave emission has also been observed indicative of REB-plasma electron two-stream instability. Plasma channel density measurements indicate that the two-stream instability can become dominant for measured f e values slightly above unity. The author has introduced a theoretical analysis for high-current REB transport and modulation in axially periodic IFR plasma channels. Analytic expression for the electric field are found for the case of a cosine modulation of the channel ion density. Two different types of channels are considered: (i) periodic beam-induced ionization channels, and (ii) periodic plasma slab channels created by an external source. Analytical conditions are derived for the matched radius of the electron beam and for approximate beam envelope motion using a 'smooth' approximation. Numerical solutions to the envelope equation show that by changing the wavelength or the amplitude of the space-charge neutralization fraction of the ion channel density modulation, the beam can be made to focus and diverge, or to undergo stable, modulated transport

  8. Focused Ion Beam and Advanced Electron Microscopy for Minerals: Insights and Outlook from Bismuth Sulphosalts

    Directory of Open Access Journals (Sweden)

    Cristiana L. Ciobanu

    2016-10-01

    Full Text Available This paper comprises a review of the rapidly expanding application of nanoscale mineral characterization methodology to the study of ore deposits. Utilising bismuth sulphosalt minerals from a reaction front in a skarn assemblage as an example, we illustrate how a complex problem in ore petrology, can be approached at scales down to that of single atoms. We demonstrate the interpretive opportunities that can be realised by doing this for other minerals within their petrogenetic contexts. From an area defined as Au-rich within a sulphosalt-sulphide assemblage, and using samples prepared on a Focused Ion Beam–Scanning Electron Microscopy (SEM platform, we identify mineral species and trace the evolution of their intergrowths down to the atomic scale. Our approach progresses from a petrographic and trace element study of a larger polished block, to high-resolution Transmission Electron Microscopy (TEM and High Angle Annular Dark Field (HAADF Scanning-TEM (STEM studies. Lattice-scale heterogeneity imaged in HAADF STEM mode is expressed by changes in composition of unit cell slabs followed by nanoparticle formation and their growth into “veins”. We report a progressive transition from sulphosalt species which host lattice-bound Au (neyite, lillianite homologues; Pb-Bi-sulphosalts, to those that cannot accept Au (aikinite. This transition acts as a crystal structural barrier for Au. Fine particles of native gold track this progression over the scale of several hundred microns, leading to Au enrichment at the reaction front defined by an increase in the Cu gradient (several wt %, and abrupt changes in sulphosalt speciation from Pb-Bi-sulphosalts to aikinite. Atom-scale resolution imaging in HAADF STEM mode allows for the direct visualisation of the three component slabs in the neyite crystal structure, one of the largest and complex sulphosalts of boxwork-type. We show for the first time the presence of aikinite nanoparticles a few nanometres in

  9. Fabrication of Amorphous Indium Gallium Zinc Oxide Thin Film Transistor by using Focused Ion Beam

    Science.gov (United States)

    Zhu, Wencong

    Compared with other transparent semiconductors, amorphous indium gallium zinc oxide (a-IGZO) has both good uniformity and high electron mobility, which make it as a good candidate for displays or large-scale transparent circuit. The goal of this research is to fabricate alpha-IGZO thin film transistor (TFT) with channel milled by focused ion beam (FIB). TFTs with different channel geometries can be achieved by applying different milling strategies, which facilitate modifying complex circuit. Technology Computer-Aided Design (TCAD) was also introduced to understand the effect of trapped charges on the device performance. The investigation of the trapped charge at IGZO/SiO2 interface was performed on the IGZO TFT on p-Silicon substrate with thermally grown SiO2 as dielectric. The subgap density-of-state model was used for the simulation, which includes conduction band-tail trap states and donor-like state in the subgap. The result shows that the de-trapping and donor-state ionization determine the interface trapped charge density at various gate biases. Simulation of IGZO TFT with FIB defined channel on the same substrate was also applied. The drain and source were connected intentionally during metal deposition and separated by FIB milling. Based on the simulation, the Ga ions in SiO2 introduced by the ion beam was drifted by gate bias and affects the saturation drain current. Both side channel and direct channel transparent IGZO TFTs were fabricated on the glass substrate with coated ITO. Higher ion energy (30 keV) was used to etch through the substrate between drain and source and form side channels at the corner of milled trench. Lower ion energy (16 keV) was applied to stop the milling inside IGZO thin film and direct channel between drain and source was created. Annealing after FIB milling removed the residual Ga ions and the devices show switch feature. Direct channel shows higher saturation drain current (~10-6 A) compared with side channel (~10-7 A) because

  10. The role of off-focus radiation in scatter correction for dedicated cone beam breast CT.

    Science.gov (United States)

    Shi, Linxi; Vedantham, Srinivasan; Karellas, Andrew; Zhu, Lei

    2018-01-01

    Dedicated cone beam breast CT (CBBCT) suffers from x-ray scatter contamination. We aim to identify the source of the significant difference between the scatter distributions estimated by two recent methods proposed by our group and to investigate its effect on CBBCT image quality. We recently proposed two novel methods of scatter correction for CBBCT, using a library based (LB) technique and a forward projection (FP) model. Despite similar enhancement on CBBCT image qualities, these two methods obtain very different scatter distributions. We hypothesize that the off-focus radiation (OFR) is the contributor and results in nontrivial signals in x-ray projections, which is ignored in the scatter estimation via the LB method. Experiments using a thin wire test tool are designed to study the effect of OFR on CBBCT spatial resolution by measuring the point spread function (PSF) and the modulation transfer function (MTF). A narrow collimator setting is used to suppress the OFR-induced signals. In addition, "PSFs" and "MTFs" are measured on clinical CBBCT images obtained by the LB and FP methods using small calcifications as point sources. The improvement of spatial resolution achieved by suppressing OFR in the wire experiment as well as in the clinical study is quantified by the improvement ratios of PSFs and spatial frequencies at different MTF values. Our hypothesis that OFR causes the imaging difference between the FP and LB methods is verified if these ratios obtained from experimental and clinical data are consistent. In the wire experiment, the results show that suppression of OFR increases the maximum signal of the PSF by about 14% and reduces the full-width-at-half-maximum (FWHM) by about 12.0%. Similar improvement on spatial resolution is achieved by the FP method compared with the LB method in the patient study. The improvement ratios of spatial frequencies at different MTF values without OFR match very well in both studies at a level of around 16%, with an

  11. Effects of beamline components (undulator, monochromator, focusing device) on the beam intensity at ID18F (ESRF)

    CERN Document Server

    Somogyi, A; Vekemans, B; Vincze, L; Simionovici, A; Adams, F

    2003-01-01

    The ID18F microprobe end-station of the European Synchrotron Radiation Facility (ESRF) is dedicated to precise and reproducible quantitative X-ray fluorescence analysis in the ppm level with =19 and micron-size spatial resolution. In order to fulfill this requirement the precise monitoring and normalization of the intensity variation of the focused micro-beam is necessary. The various effects influencing the intensity variation, hence the stability of the mu-beam, were investigated by placing different detectors (miniature ionization chamber, photodiodes) into the monochromatic beam. The theoretical statistical error of the measured signal in each detector was estimated on the basis of the absorption and e sup - -ion-pair production processes and was compared with the measured statistical errors.

  12. LICORNE: A new and unique facility for producing intense, kinematically focused neutron beams at the IPN Orsay

    Directory of Open Access Journals (Sweden)

    Wilson J.N.

    2013-12-01

    Full Text Available LICORNE is a new neutron source recently installed at the tandem accelerator of the Institut de Physique Nucléaire d'Orsay, where a Li7-beam is used to bombard a hydrogen-containing target to produce an intense forward-directed neutron beam. The directionality of the beam, which is the unique characteristic of LICORNE, will permit the installation of γ-ray detectors dedicated to the investigation of fission fragment de-excitation which are unimpeded by neutrons from the source. A first experimental program will focus on the measurement of prompt γ-ray emission in the neutron-induced fission of fertile and fissile isotopes at incident neutron energies relevant for the core design of Generation-IV nuclear reactors. Other potential uses of the LICORNE facility for both fundamental and applied physics research are also presented.

  13. Focused ion beam-assisted technology in sub-picolitre micro-dispenser fabrication

    International Nuclear Information System (INIS)

    Lopez, M J; Campo, E M; Perez-Castillejos, R; Esteve, J; Plaza, J A; Caballero, D; Errachid, A

    2008-01-01

    Novel medical and biological applications are driving increased interest in the fabrication of micropipette or micro-dispensers. Reduced volume samples and drug dosages are prime motivators in this effort. We have combined microfabrication technology with ion beam milling techniques to successfully produce cantilever-type polysilicon micro-dispensers with 3D enclosed microchannels. The microfabrication technology described here allows for the designing of nozzles with multiple shapes. The contribution of ion beam milling has had a large impact on the fabrication process and on further customizing shapes of nozzles and inlet ports. Functionalization tests were conducted to prove the viability of ion beam-fabricated micro-dispensers. Self-assembled monolayers were successfully formed when a gold surface was patterned with a thiol solution dispensed by the fabricated micro-dispensers

  14. Polarization independent high transmission large numerical aperture laser beam focusing and deflection by dielectric Huygens' metasurfaces

    Science.gov (United States)

    Özdemir, Aytekin; Hayran, Zeki; Takashima, Yuzuru; Kurt, Hamza

    2017-10-01

    In this letter, we propose all-dielectric Huygens' metasurface structures to construct high numerical aperture flat lenses and beam deflecting devices. The designed metasurface consists of two-dimensional array of all-dielectric nanodisk resonators with spatially varying radii, thereby introducing judiciously designed phase shift to the propagating light. Owing to the overlap of Mie-type magnetic and electric resonances, high transmission was achieved with rigorous design analysis. The designed flat lenses have numerical aperture value of 0.85 and transmission values around 80%. It also offers easy fabrication and compatibility with available semiconductor technology. This spectrally and physically scalable, versatile design could implement efficient wavefront manipulation or beam shaping for high power laser beams, as well as various optical microscopy applications without requiring plasmonic structures that are susceptible to ohmic loss of metals and sensitive to the polarization of light.

  15. Study of instabilities and emittance growth in periodic focusing systems for intense beams. Technical report No. PP 82-142. Progress report

    International Nuclear Information System (INIS)

    Reiser, M.

    1982-03-01

    Experimental studies of beam properties and nonlinear effects with one and two solenoid lenses have yielded a large amount of valuable data. Several phenomena were identified and explored such as images and halos and formation of pronounced hollow beam profiles after passage through the lenses. The hollow beam effect is qualitatively attributed to nonlinear space charge forces and lens aberrations. The main research effort during the past year was devoted to the experimental investigation of beam focusing with one and two solenoid lenses

  16. Propagation characteristics of a focused laser beam in a strontium barium niobate photorefractive crystal under reverse external electric field.

    Science.gov (United States)

    Guo, Q L; Liang, B L; Wang, Y; Deng, G Y; Jiang, Y H; Zhang, S H; Fu, G S; Simmonds, P J

    2014-10-01

    The propagation characteristics of a focused laser beam in a SBN:75 photorefractive crystal strongly depend on the signal-to-background intensity ratio (R=Is/Ib) under reverse external electric field. In the range 20>R>0.05, the laser beam shows enhanced self-defocusing behavior with increasing external electric field, while it shows self-focusing in the range 0.03>R>0.01. Spatial solitons are observed under a suitable reverse external electric field for R=0.025. A theoretical model is proposed to explain the experimental observations, which suggest a new type of soliton formation due to "enhancement" not "screening" of the external electrical field.

  17. Imperative function of electron beams in low-energy plasma focus ...

    Indian Academy of Sciences (India)

    2015-04-12

    Apr 12, 2015 ... observed using an array of PIN diode detectors, and the electron beam energy was detected using a scintillator-assisted ... sions. SXR pulses were generally correlated in time with peak voltage and current dip, .... The transmission curves of the BPX65 diode were attached with the associated absorption ...

  18. Ultra-high aspect ratio replaceable AFM tips using deformation-suppressed focused ion beam milling

    DEFF Research Database (Denmark)

    Savenko, Alexey; Yildiz, Izzet; Petersen, Dirch Hjorth

    2013-01-01

    in terms of defining the shape and size of the tip. Due to beam-induced deformation, it has so far not been possible to define HAR structures using lateral FIB milling. In this work we obtain aspect ratios of up to 45, with tip diameters down to 9 nm, by a deformation-suppressing writing strategy. Several...

  19. Measurement of the radial temperature distribution of the heated spot produced by a focused laser beam using an optical pyrometer.

    Science.gov (United States)

    Hendricks, L J; Zobrist, S P

    1981-05-15

    A method is described for the evaluation of the Gaussian curve parameters needed for the description of the temperature distribution of the heated spot produced on a target substrate by a well-focused laser beam, using an optical pyrometer to read the weighted average temperatures from two distinct distances. The parameter so found gave a calculated distribution curve in excellent agreement with experimental determinations of that distribution.

  20. A new route to nanoscale tomographic chemical analysis: Focused ion beam-induced auger electron spectrosocpy

    Science.gov (United States)

    Parvaneh, Hamed

    This research project is aimed to study the application of ion-induced Auger electron spectroscopy (IAES) in combination with the characteristics of focused ion beam (FIB) microscopy for performing chemical spectroscopy and further evaluate its potential for 3-dimensional chemical tomography applications. The mechanism for generation of Auger electrons by bombarding ions is very different from its electron induced counterpart. In the conventional electron-induced Auger electron spectroscopy (EAES), an electron beam with energy typically in the range 1-10kV is used to excite inner-shell (core) electrons of the solid. An electron from a higher electron energy state then de-excites to fill the hole and the extra energy is then transferred to either another electron, i.e. the Auger electron, or generation of an X-ray (photon). In both cases the emitting particles have charac-teristic energies and could be used to identify the excited target atoms. In IAES, however, large excitation cross sections can occur by promotion of in-ner shell electrons through crossing of molecular orbitals. Originally such phenomenological excitation processes were first proposed [3] for bi-particle gas phase collision systems to explain the generation of inner shell vacancies in violent collisions. In addition to excitation of incident or target atoms, due to a much heavier mass of ions compared to electrons, there would also be a substantial momentum transfer from the incident to the target atoms. This may cause the excited target atom to recoil from the lattice site or alternatively sputter off the surface with the possibility of de-excitation while the atom is either in motion in the matrix or traveling in vacuum. As a result, one could expect differences between the spectra induced by incident electrons and ions and interpretation of the IAE spectra requires separate consideration of both excitation and decay processes. In the first stage of the project, a state-of-the-art mass

  1. Tight focusing of a higher-order radially polarized beam transmitting through multi-zone binary phase pupil filters.

    Science.gov (United States)

    Guo, Hanming; Weng, Xiaoyu; Jiang, Man; Zhao, Yanhui; Sui, Guorong; Hu, Qi; Wang, Yang; Zhuang, Songlin

    2013-03-11

    When the pupil filters are used to improve the performance of the imaging system, the conversion efficiency is a critical characteristic for real applications. Here, in order to take full advantage of the subwavelength focusing property of the radially polarized higher-order Laguerre-Gaussian (LG) beam, we introduce the multi-zone binary phase pupil filters into the imaging system to deal with the problem that the focal spot is split along the z axis for the small size parameter of the incident LG beam. We provide an easy-to-perform procedure for the design of multi-zone binary phase pupil filters, where the zone numbers of π phase are uncertain when the optimizing procedure starts. Based on this optimizing procedure, we successfully find the set of optimum structures of a seventeen-belt binary phase pupil filters and generate the excellent focal spot, where the depth of focus, the focal spot transverse size, the Strehl ratio, and the sidelobe intensity are 9.53λ, 0.41λ, 41.75% and 16.35% in vacuum, respectively. Most importantly, even allowing the power loss of the incident LG beam truncated by the pupil of the imaging system, the conversion efficiency is still as high as 37.3%. Theoretical calculations show that we succeed to have sufficient conversion efficiency while utilizing the pupil filters to decrease the focal spot and extend the depth of focus.

  2. Xenon focused ion beam in the shape memory alloys investigation – the case of NiTi and CoNiAl

    Czech Academy of Sciences Publication Activity Database

    Kopeček, Jaromír; Jurek, Karel; Kopecký, Vít; Klimša, Ladislav; Seiner, Hanuš; Sedlák, Petr; Landa, Michal; Dluhoš, J.; Petrenec, M.; Hladík, L.; Doupal, A.; Heczko, Oleg

    2014-01-01

    Roč. 20, Aug (2014), s. 335-336 ISSN 1431-9276 R&D Projects: GA ČR(CZ) GA14-03044S Institutional support: RVO:68378271 ; RVO:61388998 Keywords : scanning electron microscope * SEM * focused ion beam * FIB * xenon plasma focused ion beam * dual beam * shape memory alloy * SMA Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.877, year: 2014

  3. Electron-stimulated purification of platinum nanostructures grown via focused electron beam induced deposition

    Directory of Open Access Journals (Sweden)

    Brett B. Lewis

    2015-04-01

    Full Text Available Platinum–carbon nanostructures deposited via electron beam induced deposition from MeCpPt(IVMe3 are purified during a post-deposition electron exposure treatment in a localized oxygen ambient at room temperature. Time-dependent studies demonstrate that the process occurs from the top–down. Electron beam energy and current studies demonstrate that the process is controlled by a confluence of the electron energy loss and oxygen concentration. Furthermore, the experimental results are modeled as a 2nd order reaction which is dependent on both the electron energy loss density and the oxygen concentration. In addition to purification, the post-deposition electron stimulated oxygen purification process enhances the resolution of the EBID process due to the isotropic carbon removal from the as-deposited materials which produces high-fidelity shape retention.

  4. A twelve month study of PM2.5 and PM10 fine particle aerosol composition in the Sydney region using ion beam analysis techniques. Appendix 2

    International Nuclear Information System (INIS)

    Cohen, David D.; Bailey, G.M.; Kondepudi, Ramesh

    1995-01-01

    The accelerator based ion beam (IBA) analysis techniques of PIXE, PIGME, PESA, and RBS have been used to characterise fine particles at selected sites in the Sydney region. The four techniques operating simultaneously provide elemental concentrations on 24 chemical species, including H, Q N, 0, F, Na, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Cu, Ni, Zn, Br and Pb. The total mass and the elemental carbon by laser integrated plate techniques were also measured. A stacked filter system, built by the University of Gent, Belgium and supplied by the IAEA was used to provide fine particle data on PM2.5 and PM10 particles. While a cyclone sampler, built at ANSTO, Lucas Heights, was used to provide data on PM2.5 particles only. The two different types of units were operated along side each other for the whole of 1994 and the results compared. The use of the multi-elemental IBA techniques also allowed for some fine particle source fingerprinting to be performed. (author)

  5. Study and use of the ion beams formed in the Focus experiment

    International Nuclear Information System (INIS)

    Bernard, A.; Garconnet, J.P.; Jolas, A.; le Breton, J.P.; de Mascureau, J.

    1983-03-01

    Studies were performed in the 200 kJ Actime installation using CD 2 or LiD targets and permitted one to determine the characteristics of the ion beam which bombards the target. The measurement of the temperature attained by metal targets bombarded by deuterons is discussed. The use of a digital program permits one to calculate the amount of energy deposited. Finally, the improvements being considered and the future prospects offered by this type of experiment are discussed

  6. Magnetic focusing of an intense slow positron beam for enhanced depth-resolved analysis of thin films and interfaces

    CERN Document Server

    Falub, C V; Mijnarends, P E; Schut, H; Veen, A V

    2002-01-01

    The intense reactor-based slow positron beam (POSH) at the Delft research reactor has been coupled to a Two-Dimensional Angular Correlation of Annihilation Radiation (2D-ACAR) setup. The design is discussed with a new target chamber for the 2D-ACAR setup based on Monte Carlo simulations of the positron trajectories, beam energy distribution and beam transmission in an increasing magnetic field gradient. Numerical simulations and experiment show that when the slow positron beam with a FWHM of 11.6 mm travels in an increasing axial magnetic field created by a strong NdFeB permanent magnet, the intensity loss is negligible above approx 6 keV and a focusing factor of 5 in diameter is achieved. Monte Carlo simulations and Doppler broadening experiments in the target region show that in this configuration the 2D-ACAR setup can be used to perform depth sensitive studies of defects in thin films with a high resolution. The positron implantation energy can be varied from 0 to 25 keV before entering the non-uniform mag...

  7. Intense electron-beam transport in the ion-focused regime through the collision-dominated regime

    International Nuclear Information System (INIS)

    Sanford, T.W.L.; Poukey, J.W.; Welch, D.R.; Mock, R.C.

    1993-01-01

    This paper reviews the transport of the 19-MeV, 700-kA, 25-ns Hermes-III electron beam in long gas cells filled with N 2 gas spanning six decades in pressure from 10 3 to ∼10 3 Torr. We show through measurements and theoretical analyses that the beam has two windows of stable transport: a low-pressure window (between ∼1 and ∼100 mTorr) that is dominated by propagation in the semi-collisionless IFR (ion-focused regime), and a high-pressure window (between ∼1 and ∼100 Torr) that is dominated by propagation in the resistive CDR (collision-dominated regime). In the CDR, 79±1.5% of the beam energy is transported over 11 m at 20 Torr. In the IFR, we show that intense radiation fields with controllable rise times and pulse widths can be generated on axis at a bremsstrahlung target. In summary, the measurements and analyses presented here provide a quantitative description of the Hermes-III beam transport over six decades in pressure

  8. Overview on neutron beam industry-focused strategic research in Malaysia

    International Nuclear Information System (INIS)

    Abdul Aziz Mohamed; Razali Kassim; Abdul Jalil Abdul Hamid; Azali Muhammad; Muhammad Rawi Mohd Zain; Azhar Azmi

    2002-01-01

    The TRIGA MARK II research reactor (RTP) at the Malaysian Institute for Nuclear Technology Research (MINT) was commissioned in July 1982. RTP is a 1 MW steady state reactor which being used for reactor training and research related to neutron. Since then various works have been performed to utilise the neutrons produced from this steady state reactor. Projects undertaken are the development and utilization of the neutron radiography (myNR) and small angle neutron scattering (mySANS) facilities. This poster highlights the recent status the above neutron beam facilities and their application in materials science and technology research and education. (Author)

  9. Non-linear propagation of laser beam and focusing due to self ...

    Indian Academy of Sciences (India)

    ... self-focusing analysis indicates that the Kerr non-linearity acts as a perturbation on the radial inhomogeneity due to fiber geometry. Analysis indicates that the paraxial rays and peripheral rays focus at different points, indicating aberration effect. Calculated critical power matches with the experimentally reported result.

  10. Efficient focusing of 8 keV X-rays with multilayer Fresnel zone plates fabricated by atomic layer deposition and focused ion beam milling

    International Nuclear Information System (INIS)

    Mayer, Marcel; Keskinbora, Kahraman; Grévent, Corinne; Szeghalmi, Adriana; Knez, Mato; Weigand, Markus; Snigirev, Anatoly; Snigireva, Irina; Schütz, Gisela

    2013-01-01

    The fabrication and performance of multilayer Al 2 O 3 /Ta 2 O 5 Fresnel zone plates in the hard X-ray range and a discussion of possible future developments considering available materials are reported. Fresnel zone plates (FZPs) recently showed significant improvement by focusing soft X-rays down to ∼10 nm. In contrast to soft X-rays, generally a very high aspect ratio FZP is needed for efficient focusing of hard X-rays. Therefore, FZPs had limited success in the hard X-ray range owing to difficulties of manufacturing high-aspect-ratio zone plates using conventional techniques. Here, employing a method of fabrication based on atomic layer deposition (ALD) and focused ion beam (FIB) milling, FZPs with very high aspect ratios were prepared. Such multilayer FZPs with outermost zone widths of 10 and 35 nm and aspect ratios of up to 243 were tested for their focusing properties at 8 keV and shown to focus hard X-rays efficiently. This success was enabled by the outstanding layer quality thanks to ALD. Via the use of FIB for slicing the multilayer structures, desired aspect ratios could be obtained by precisely controlling the thickness. Experimental diffraction efficiencies of multilayer FZPs fabricated via this combination reached up to 15.58% at 8 keV. In addition, scanning transmission X-ray microscopy experiments at 1.5 keV were carried out using one of the multilayer FZPs and resolved a 60 nm feature size. Finally, the prospective of different material combinations with various outermost zone widths at 8 and 17 keV is discussed in the light of the coupled wave theory and the thin-grating approximation. Al 2 O 3 /Ir is outlined as a promising future material candidate for extremely high resolution with a theoretical efficiency of more than 20% for as small an outermost zone width as 10 nm at 17 keV

  11. Fabrication of nano-scaled polymer-derived SiAlCN ceramic components using focused ion beam

    Science.gov (United States)

    Tian, Ye; Shao, Gang; Wang, Xingwei; An, Linan

    2013-09-01

    Fully dense polymer-derived amorphous silicoaluminum carbonitride (SiAlCN) ceramics were synthesized from polysilazane as preceramic precursors followed by a thermal decomposition process. The nanofabrication of amorphous SiAlCN ceramics was implemented with a focused ion beam (FIB). FIB conditions such as the milling rate, the beam current, and the number of passes were considered. It was found that nanopatterns with a feature size of less than 100 nm could be fabricated onto polymer-derived ceramics (PDCs) precisely and quickly. Specific nanostructures of thin walls, nozzle, and gear have been fabricated as demonstrations, indicating that the FIB technique was a promising method to realize nanostructures on PDCs, especially for microelectromechanical system and micro/nano-sensor applications.

  12. Fabrication of nano-scaled polymer-derived SiAlCN ceramic components using focused ion beam

    International Nuclear Information System (INIS)

    Tian, Ye; Wang, Xingwei; Shao, Gang; An, Linan

    2013-01-01

    Fully dense polymer-derived amorphous silicoaluminum carbonitride (SiAlCN) ceramics were synthesized from polysilazane as preceramic precursors followed by a thermal decomposition process. The nanofabrication of amorphous SiAlCN ceramics was implemented with a focused ion beam (FIB). FIB conditions such as the milling rate, the beam current, and the number of passes were considered. It was found that nanopatterns with a feature size of less than 100 nm could be fabricated onto polymer-derived ceramics (PDCs) precisely and quickly. Specific nanostructures of thin walls, nozzle, and gear have been fabricated as demonstrations, indicating that the FIB technique was a promising method to realize nanostructures on PDCs, especially for microelectromechanical system and micro/nano-sensor applications. (paper)

  13. Focused-ion-beam induced damage in thin films of complex oxide BiFeO3

    Directory of Open Access Journals (Sweden)

    W. Siemons

    2014-02-01

    Full Text Available An unexpected, strong deterioration of crystal quality is observed in epitaxial perovskite BiFeO3 films in which microscale features have been patterned by focused-ion-beam (FIB milling. Specifically, synchrotron x-ray microdiffraction shows that the damaged region extends to tens of μm, but does not result in measureable changes to morphology or stoichiometry. Therefore, this change would go undetected with standard laboratory equipment, but can significantly influence local material properties and must be taken into account when using a FIB to manufacture nanostructures. The damage is significantly reduced when a thin metallic layer is present on top of the film during the milling process, clearly indicating that the reduced crystallinity is caused by ion beam induced charging.

  14. Teaching an Old Material New Tricks: Easy and Inexpensive Focused Ion Beam (FIB) Sample Protection Using Conductive Polymers.

    Science.gov (United States)

    Taillon, Joshua A; Ray, Valery; Salamanca-Riba, Lourdes G

    2017-08-01

    This letter describes an innovative spin-coating system, built from off-the-shelf components, that can easily and inexpensively be integrated into any laboratory environment. Combined with a liquid suspension of conductive polymer, such a "rotary coater" enables simple coating of planar samples to create a physical protective barrier on the sample surface. This barrier aids in charge dissipation during scanning electron microscope and focused ion beam (FIB) imaging and provides wide-scale protection of the sample surface from ion bombardment during FIB imaging and gas-assisted deposition. This polymer layer replaces the localized and time-consuming electron beam deposition step typically performed during transmission electron microscopy lamella preparation. After observation, the coating can be easily removed, if desired. The described spin-coating procedure has minimal cost while providing repeatable positive results, without the need for expensive commercial coating instrumentation.

  15. Focused ion beam modification of surfaces for directed self-assembly of InAs/GaAs(001) quantum dots

    International Nuclear Information System (INIS)

    McKay, Hugh; Rudzinski, Paul; Dehne, Aaron; Millunchick, Joanna Mirecki

    2007-01-01

    Controlled nucleation of InAs quantum dots has been achieved by Ga + focused ion beam modification of GaAs(100) surfaces. Quantum dots may be induced in irradiated regions despite the fact that the deposited thickness is less than the critical thickness for their formation under typical growth conditions when the ion dose is greater than 10 13 ions cm -2 . We also find that the dot density increases with increasing ion dose, and reaches saturation for D>10 14 ions cm -2 . Parameters such as dot height and diameter are unaffected by the dose level. Thus, we show that the increase in dot density is a result of diffusion of adatoms from outside the patterned region. The mechanism for enhanced quantum dot formation is due to the formation of monolayer deep holes created in the substrate by the ion beam, which may be used to form regular arrays of quantum dots

  16. The generation of a complete spiral spot and multi split rings by focusing three circularly polarized vortex beams

    Science.gov (United States)

    Chen, Jiannong; Gao, Xiumin; Zhu, Linwei; Xu, Qinfeng; Ma, Wangzi

    2014-05-01

    We demonstrate that a complete right-handed or left-handed spiral-shaped focus can be created by focusing circularly polarized and three spatially shifted vortex beams through high numerical objective. By dividing the back aperture into multi annular zones and applying an additional phase term, the multi focal spots aligned along z axis of individual three dimensional focal shapes can be generated. The spiral shaped focus provides a pathway of manipulating the micro-particles in a curved trajectory and opens up a possibility of measuring mechanical torque of biological large molecules such as DNA by chemically binding one end on the cover-glass. The multi focal spots aligned along the z axis can eliminate the need of z axis scanning in the direct laser writing fabrication of some metamaterials which is composed of three-dimensional array of specific shapes of building blocks.

  17. Fabrication of Molds with 25-nm Dot-Pitch Pattern by Focused Ion Beam and Reactive Ion Etching for Nanoimprint Using Metallic Glass

    Science.gov (United States)

    Fukuda, Yasuyuki; Saotome, Yasunori; Nishiyama, Nobuyuki; Saidoh, Noriko; Makabe, Eiichi; Inoue, Akihisa

    2012-08-01

    Here we attempted to fabricate molds (dies) of nanodot arrays with a 25-nm pitch and to nanoimprint metallic glass for developing bit-patterned media with an ultrahigh recording density of 1 Tbit/in.2. The mold-fabricating process consisted of mask patterning by focused ion beam assisted chemical vapor deposition (FIB-CVD) and reactive ion etching (RIE). We investigated the feasibility of a Pt-deposited metal etching mask on SiO2 on Si and diamond like carbon (DLC) on Al2O3 substrates, and achieved isolated convex nanodot arrays with a 25-nm pitch and an aspect ratio of 1.8 by RIE with O2 plasma on a DLC/Al2O3 substrate. Subsequently, we nanoimprinted Pt-based metallic glass by using the fabricated molds and successfully replicated fine concave nanohole arrays. The results suggest that the FIB-CVD/RIE process is a promising technique for fabricating ultrafine nanopatterned molds, and metallic glasses are ideal nanoimprintable materials for mass producing nanodevices such as bit-patterned media.

  18. Critical power for self-focusing of optical beam in absorbing media

    Science.gov (United States)

    Qi, Pengfei; Zhang, Lin; Lin, Lie; Zhang, Nan; Wang, Yan; Liu, Weiwei

    2018-04-01

    Self-focusing effects are of central importance for most nonlinear optical effects. The critical power for self-focusing is commonly investigated theoretically without considering a material’s absorption. Although this is practicable for various materials, investigating the critical power for self-focusing in media with non-negligible absorption is also necessary, because this is the situation usually met in practice. In this paper, the simple analytical expressions describing the relationships among incident power, absorption coefficient and focal position are provided by a simple physical model based on the Fermat principle. Expressions for the absorption dependent critical power are also derived; these can play important roles in experimental and applied research on self-focusing-related nonlinear optical phenomena in absorbing media. Numerical results, based on the nonlinear wave equation—and which can predict experimental results perfectly—are also presented, and agree quantitatively with the analytical results proposed in this paper.

  19. Decline of the self-focusing of a pulsed high intensity electron beam owing to gas breakdown

    International Nuclear Information System (INIS)

    Hotta, H.; Arai, H.

    1977-01-01

    The self-focusing of a pulsed high-intensity electron beam in a gas declines in the intermediate pressure region owing to gas breakdown. The degree of the self-focusing of a beam from a Febetron 706 in monatomic gases increases by increasing the breakdown time (t/sub B/), which is defined as the time when the plasma conductivity becomes 10 mho/cm. Secondary electrons are consumed appreciably in polyatomic gases after t/sub B/ through their reactions with ions and neutral molecules. Therefore, in such gases, the amount of the consumption must be estimated to analyze the self-focusing. For the estimation of the consumption, we must remark that the mean energy of secondary electrons is quite different between before and after t/sub B/ because of the different strength of induced longitudinal electric field. As a result of the numerical analyses, we obtain the equation t/sub B/-t/sub N/ =12/w (α-eta) (t/sub N/ is neutralization time, w is electron drift velocity, α is the first Townsend ionization coefficient, and eta is the electron attachment coefficient). Since eta is usually negligibly small before t/sub B/ and t/sub N/ is also negligibly small above a certain pressure, t/sub B/ is approximately inversely proportional to wα. The t/sub B/ in polyatomic gases, however, must be corrected for the consumption described above

  20. Output optics for Aurora: Beam separation, pulse stacking, and target focusing

    International Nuclear Information System (INIS)

    McLeod, J.

    1987-01-01

    An end-to-end technology demonstration prototype for large-scale ultraviolet laser systems of interest for short wavelength, inertial confinement fusion (ICF) investigations. The system is designed to employ optical angular multiplexing and serial amplification by electron-beam-driven KrF laser amplifiers to deliver to ICF targets a stack of pulses with a duration of 5 ns containing several kilojoules at a wavelength of 248 nm. The optical system has been designed in two phases. The first phase carries only through the amplifier train and does not include a target chamber or any demultiplexing. During first-phase design, the system was conceived of as only an amplifier demonstration and not as an end-to-end system demonstration. The design concept for second-phase optics that provides demultiplexing and carries the laser light to target is presented

  1. Nonlinear self-focus of pulsed-wave beams in Kerr media

    Energy Technology Data Exchange (ETDEWEB)

    Judkins, Justin Boyd [Univ. of Arizona, Tucson, AZ (United States)

    1992-01-01

    A modified finite-difference time-domain method for solving Maxwell`s equations in nonlinear media is presented. This method allows for a finite response time to be incorporated in the medium, physically creating dispersion and absorption mechanisms. The technique models electromagnetic fields in two space dimensions and time and encompasses both the TEz and TMz set of decoupled field equations. Aspects of an ultra-short pulsed Gaussian beam are studied in a variety of linear and nonlinear environments to demonstrate that the methods developed here can be used efficaciously in the modeling of pulses in complex problem space geometries even when nonlinearities are present.

  2. Broad and focused ion beams Ga+ implantation damage in the fabrication of p+-n Si shallow junctions

    International Nuclear Information System (INIS)

    Steckl, A.J.; Lin, C.M.; Patrizio, D.; Rai, A.K.; Pronko, P.P.

    1989-01-01

    The use of focused and broad beam Ga + implantation for the fabrication of p + -n Si shallow junctions is explored. In particular, the issue of ion induced damage and its effect on diode electrical properties is explored. FIB-fabricated junctions exhibit a deeper junction with lower sheet resistance and higher leakage current than the BB-implanted diodes. TEM analysis exhibits similar amorphization and recrystallization behavior for both implantation techniques with the BB case generating a higher dislocation loop density after a 900 degree C anneal. 6 refs., 5 figs., 1 tab

  3. Fabrication of low-loss silicon-on-oxidized-porous-silicon strip waveguide using focused proton-beam irradiation

    OpenAIRE

    Teo, EJ; Bettiol, AA; Yang, P; Breese, MBH; Xiong, BQ; Mashanovich, GZ; Headley, WR; Reed, GT

    2009-01-01

    we have successfully fabricated low-loss silicon-on-oxidized-porous-silicon (SOPS) strip waveguides with high-index contrast using focused proton-beam irradiation and electrochemical etching. Smooth surface quality with rms roughness of 3.1 nm is achieved for a fluence of 1 x 10(15)/cm(2) after postoxidation treatment. Optical characterization at a wavelength of 1550 nm shows a loss of 1.1 +/- 0.4 dB/cm and 1.2 +/- 0.4 dB/cm in TE and TM polarization respectively, which we believe is the lowe...

  4. Deposition of metallic gallium on re-crystallized ceramic material during focused ion beam milling

    Energy Technology Data Exchange (ETDEWEB)

    Muñoz-Tabares, J.A., E-mail: j.a.munoz.tabares@gmail.com [Instituto de Física, Universidad Nacional Autónoma de México, Circuito de la Investigación Científica s/n, Cd Universitaria, 04510 México DF, México (Mexico); Anglada, M. [Departament de Ciència dels Materials i Enginyeria Metallúrgica, Universitat Politècnica de Catalunya, Avda. Diagonal 647 (ETSEIB), 08028 Barcelona (Spain); Reyes-Gasga, J. [Instituto de Física, Universidad Nacional Autónoma de México, Circuito de la Investigación Científica s/n, Cd Universitaria, 04510 México DF, México (Mexico)

    2013-12-15

    We report a new kind of artifact observed in the preparation of a TEM sample of zirconia by FIB, which consists in the deposition of metallic gallium nano-dots on the TEM sample surface. High resolution TEM images showed a microstructure of fine equiaxed grains of ∼ 5 nm, with some of them possessing two particular characteristics: high contrast and well-defined fast Fourier transform. These grains could not be identified as any phase of zirconia but it was possible to identify them as gallium crystals in the zone axis [110]. Based on HRTEM simulations, the possible orientations between zirconia substrate and deposited gallium are discussed in terms of lattice mismatch and oxygen affinity. - Highlights: • We show a new type of artifact induced during preparation of TEM samples by FIB. • Deposition of Ga occurs due to its high affinity for oxygen. • Materials with small grain size (∼ 5 nm) could promote Ga deposition. • Small grain size permits the elastic accommodation of deposited Ga.

  5. Proposal to perform a high - statisics neutrino scattering experiment using a fine - grained detector in the NuMI Beam

    Energy Technology Data Exchange (ETDEWEB)

    Morfin, J.G.; /Fermilab; McFarland, K.; /Rochester U.

    2003-12-01

    The NuMI facility at Fermilab will provide an extremely intense beam of neutrinos for the MINOS neutrino-oscillation experiment. The spacious and fully-outfitted MINOS near detector hall will be the ideal venue for a high-statistics, high-resolution {nu} and {bar {nu}}-nucleon/nucleus scattering experiment. The experiment described here will measure neutrino cross-sections and probe nuclear effects essential to present and future neutrino-oscillation experiments. Moreover, with the high NuMI beam intensity, the experiment will either initially address or significantly improve our knowledge of a wide variety of neutrino physics topics of interest and importance to the elementary-particle and nuclear-physics communities.

  6. Bent crystals in Laue geometry: dynamical focusing of a polychromatic incident beam

    Czech Academy of Sciences Publication Activity Database

    Mocella, V.; Guigay, J. P.; Hrdý, Jaromír; Ferrero, C.; Hoszowska, J.

    2004-01-01

    Roč. 37, - (2004), s. 941-946 ISSN 0021-8898 Institutional research plan: CEZ:AV0Z1010921 Keywords : polychromatic focusing * bent Laue crystals * dynamical diffraction * optics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.534, year: 2004

  7. Radial focusing and energy compression of a laser-produced proton beam by a synchronous rf field

    Directory of Open Access Journals (Sweden)

    Masahiro Ikegami

    2009-06-01

    Full Text Available The dynamics of a MeV laser-produced proton beam affected by a radio frequency (rf electric field has been studied. The proton beam was emitted normal to the rear surface of a thin polyimide target irradiated with an ultrashort pulsed laser with a power density of 4×10^{18}  W/cm^{2}. The energy spread was compressed to less than 11% at the full width at half maximum (FWHM by an rf field. Focusing and defocusing effects of the transverse direction were also observed. These effects were analyzed and reproduced by Monte Carlo simulations. The simulation results show that the transversely focused protons had a broad continuous spectrum, while the peaks in the proton spectrum were defocused. Based on this new information, we propose that elimination of the continuous energy component of laser-produced protons is possible by utilizing a focal length difference between the continuous spectral protons and the protons included in the spectral peak.

  8. Multi-channel Andreev reflection in Co-W nanocontacts fabricated using focused electron/ion beam induced deposition.

    Science.gov (United States)

    Sharma, N; Vugts, P; Daniels, C; Keuning, W; Kohlhepp, J T; Kurnosikov, O; Koopmans, B

    2014-12-12

    We report multi-channel electron transport in nano-contacts fabricated using focused electron beam induced deposited (FEBID) cobalt and focused ion beam induced deposited (FIBID) tungsten. Anomalous Andreev reflection (AR) effect is observed to which the conventional Blonder-Tinkham-Klapwijk (BTK) fit cannot be applied. In specific, we have observed multiple number of shoulders near the AR peak, whose origin is unknown in literature. We explain this effect based on a simple model that takes into account the material properties of the FIBID grown W superconductor, as well as the specific interface properties that are an outcome of using FEBID/FIBID as a fabrication technique. We show that numerical calculations using the BTK approximation based on the consideration of multiple channels generate similar shoulders as we observed in the AR experiments. Electrical measurements and x-ray photoemission spectroscopy carried out on FIBID W deposits puts additional evidence towards multi-channel current transport occuring at the interface of the nanocontacts.

  9. Kinetic description of intense nonneutral beam propagation through a periodic solenoidal focusing field based on the nonlinear Vlasov-Maxwell equations

    Energy Technology Data Exchange (ETDEWEB)

    Davidson, R.C. [Princeton Univ., NJ (United States). Princeton Plasma Physics Lab.; Chen, C. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Science and Fusion Center

    1997-08-01

    A kinetic description of intense nonneutral beam propagation through a periodic solenoidal focusing field B{sup sol}({rvec x}) is developed. The analysis is carried out for a thin beam with characteristic beam radius r{sub b} {much_lt} S, and directed axial momentum {gamma}{sub b}m{beta}{sub b}c (in the z-direction) large compared with the transverse momentum and axial momentum spread of the beam particles. Making use of the nonlinear Vlasov-Maxwell equations for general distribution function f{sub b}({rvec x},{rvec p},t) and self-consistent electrostatic field consistent with the thin-beam approximation, the kinetic model is used to investigate detailed beam equilibrium properties for a variety of distribution functions. Examples are presented both for the case of a uniform solenoidal focusing field B{sub z}(z) = B{sub 0} = const. and for the case of a periodic solenoidal focusing field B{sub z}(z + S) = B{sub z}(z). The nonlinear Vlasov-Maxwell equations are simplified in the thin-beam approximation, and an alternative Hamiltonian formulation is developed that is particularly well-suited to intense beam propagation in periodic focusing systems. Based on the present analysis, the Vlasov-Maxwell description of intense nonneutral beam propagation through a periodic solenoidal focusing field {rvec B}{sup sol}({rvec x}) is found to be remarkably tractable and rich in physics content. The Vlasov-Maxwell formalism developed here can be extended in a straightforward manner to investigate detailed stability behavior for perturbations about specific choices of beam equilibria.

  10. Plasma Channel Lenses and Plasma Tornadoes for Optical Beam Focusing and Transport

    Science.gov (United States)

    Hubbard, R. F.; Kaganovich, D.; Johnson, L. A.; Gordon, D. F.; Penano, J. R.; Hafizi, B.; Helle, M. H.; Mamonau, A. A.

    2017-10-01

    Shaped plasmas offer the possibility of manipulating laser pulses at intensities far above the damage limits for conventional optics. An example is the plasma channel, which is a cylindrical plasma column with an on-axis density minimum. Long plasma channels have been widely used to guide intense laser pulses, particularly in laser wakefield accelerators. A new concept, the ``plasma tornado'', offers the possibility of creating long plasma channels with no nearby structures and at densities lower than can be achieved by capillary discharges. A short plasma channel can focus a laser pulse in much the same manner as a conventional lens or off-axis parabola. When placed in front of the focal point of an intense laser pulse, a plasma channel lens (PCL) can reduce the effective f-number of conventional focusing optics. When placed beyond the focal point, it can act as a collimator. We will present experimental and modeling results for a new plasma tornado design, review experimental methods for generating short PCLs, and discuss potential applications. Supported by the Naval Research Laboratory Base Program.

  11. Experimental study of transmission of a pulsed focused beam through a skull phantom in nonlinear regime

    Energy Technology Data Exchange (ETDEWEB)

    Tsysar, S. A., E-mail: sergey@acs366.phys.msu.ru; Nikolaeva, A. V.; Khokhlova, V. A.; Yuldashev, P. V. [Physics Faculty, Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Svet, V. D. [Andreyev Acoustics Institute, 4, Shvernik Street, Moscow 117036 (Russian Federation); Sapozhnikov, O. A. [Physics Faculty, Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105 (United States)

    2015-10-28

    In the paper the use of receiving and radiating system, which allows to determine the parameters of bone by nonlinear pulse-echo technique and to image of brain structures through the skull bones, was proposed. Accuracy of the skull bone characterization is due to higher measured harmonic and is significantly better than in linear case. In the experimental part focused piezoelectric transducer with diameter 100 mm, focal distance 100 mm, the frequency of 1.092 MHz was used. It was shown that skull bone profiling can be performed with the use of 3rd harmonic since 1st harmonic can be used for visualization of the underlying objects. The use of wideband systems for both skull profiling and brain visualization is restricted by skull attenuation and resulting low effective sensitivity.

  12. Raster-scanning serial protein crystallography using micro- and nano-focused synchrotron beams

    International Nuclear Information System (INIS)

    Coquelle, Nicolas; Brewster, Aaron S.; Kapp, Ulrike; Shilova, Anastasya; Weinhausen, Britta; Burghammer, Manfred; Colletier, Jacques-Philippe

    2015-01-01

    A raster scanning serial protein crystallography approach is presented, that consumes as low ∼200–700 nl of sedimented crystals. New serial data pre-analysis software, NanoPeakCell, is introduced. High-resolution structural information was obtained from lysozyme microcrystals (20 µm in the largest dimension) using raster-scanning serial protein crystallography on micro- and nano-focused beamlines at the ESRF. Data were collected at room temperature (RT) from crystals sandwiched between two silicon nitride wafers, thereby preventing their drying, while limiting background scattering and sample consumption. In order to identify crystal hits, new multi-processing and GUI-driven Python-based pre-analysis software was developed, named NanoPeakCell, that was able to read data from a variety of crystallographic image formats. Further data processing was carried out using CrystFEL, and the resultant structures were refined to 1.7 Å resolution. The data demonstrate the feasibility of RT raster-scanning serial micro- and nano-protein crystallography at synchrotrons and validate it as an alternative approach for the collection of high-resolution structural data from micro-sized crystals. Advantages of the proposed approach are its thriftiness, its handling-free nature, the reduced amount of sample required, the adjustable hit rate, the high indexing rate and the minimization of background scattering

  13. Raster-scanning serial protein crystallography using micro- and nano-focused synchrotron beams.

    Science.gov (United States)

    Coquelle, Nicolas; Brewster, Aaron S; Kapp, Ulrike; Shilova, Anastasya; Weinhausen, Britta; Burghammer, Manfred; Colletier, Jacques Philippe

    2015-05-01

    High-resolution structural information was obtained from lysozyme microcrystals (20 µm in the largest dimension) using raster-scanning serial protein crystallography on micro- and nano-focused beamlines at the ESRF. Data were collected at room temperature (RT) from crystals sandwiched between two silicon nitride wafers, thereby preventing their drying, while limiting background scattering and sample consumption. In order to identify crystal hits, new multi-processing and GUI-driven Python-based pre-analysis software was developed, named NanoPeakCell, that was able to read data from a variety of crystallographic image formats. Further data processing was carried out using CrystFEL, and the resultant structures were refined to 1.7 Å resolution. The data demonstrate the feasibility of RT raster-scanning serial micro- and nano-protein crystallography at synchrotrons and validate it as an alternative approach for the collection of high-resolution structural data from micro-sized crystals. Advantages of the proposed approach are its thriftiness, its handling-free nature, the reduced amount of sample required, the adjustable hit rate, the high indexing rate and the minimization of background scattering.

  14. Raster-scanning serial protein crystallography using micro- and nano-focused synchrotron beams

    Energy Technology Data Exchange (ETDEWEB)

    Coquelle, Nicolas [Université Grenoble Alpes, IBS, 38044 Grenoble (France); CNRS, IBS, 38044 Grenoble (France); CEA, IBS, 38044 Grenoble (France); Brewster, Aaron S. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Kapp, Ulrike; Shilova, Anastasya; Weinhausen, Britta [European Synchrotron Radiation Facility, BP 220, 38043 Grenoble (France); Burghammer, Manfred, E-mail: burgham@esrf.fr [European Synchrotron Radiation Facility, BP 220, 38043 Grenoble (France); Ghent University, Ghent B-9000 (Belgium); Colletier, Jacques-Philippe, E-mail: burgham@esrf.fr [Université Grenoble Alpes, IBS, 38044 Grenoble (France); CNRS, IBS, 38044 Grenoble (France); CEA, IBS, 38044 Grenoble (France)

    2015-05-01

    A raster scanning serial protein crystallography approach is presented, that consumes as low ∼200–700 nl of sedimented crystals. New serial data pre-analysis software, NanoPeakCell, is introduced. High-resolution structural information was obtained from lysozyme microcrystals (20 µm in the largest dimension) using raster-scanning serial protein crystallography on micro- and nano-focused beamlines at the ESRF. Data were collected at room temperature (RT) from crystals sandwiched between two silicon nitride wafers, thereby preventing their drying, while limiting background scattering and sample consumption. In order to identify crystal hits, new multi-processing and GUI-driven Python-based pre-analysis software was developed, named NanoPeakCell, that was able to read data from a variety of crystallographic image formats. Further data processing was carried out using CrystFEL, and the resultant structures were refined to 1.7 Å resolution. The data demonstrate the feasibility of RT raster-scanning serial micro- and nano-protein crystallography at synchrotrons and validate it as an alternative approach for the collection of high-resolution structural data from micro-sized crystals. Advantages of the proposed approach are its thriftiness, its handling-free nature, the reduced amount of sample required, the adjustable hit rate, the high indexing rate and the minimization of background scattering.

  15. Focused parathyroidectomy without intra-operative parathormone monitoring: The value of PTH assay in preoperative ultrasound guided fine needle aspiration washout.

    Science.gov (United States)

    Kuzu, Fatih; Arpaci, Dilek; Cakmak, Guldeniz Karadeniz; Emre, Ali Ugur; Elri, Tarik; Ilikhan, Sevil Uygun; Bahadir, Burak; Bayraktaoglu, Taner

    2016-03-01

    The accurate identification of hyperfunctioning parathyroid (HP) gland is the only issue for definitive surgical treatment in primary hyperparathyroidism (pHPT). Various imaging and operative techniques have been proposed to confirm the localization of the diseased gland. Nevertheless, none of these methods proved to be the gold standard. The presented study aimed to assess the value of parathyroid hormone assay in preoperative ultrasound guided fine needle aspiration (FNA)-PTH washout fluid to verify the correct localisation for focused parathyroidectomy without intra-operative PTH monitoring. The retrospective analysis of 57 patients with pHPT who underwent FNA-PTH was conducted from a prospective database. Biochemical assessment together with radiological (ultrasonography) and nuclear (MIBI scan) imaging was reviewed. Associations between FNA-PTH washout values and localization technics were evaluated and compared in terms of operative findings. Focused parathyroidectomy without intraoperative PTH monitoring was performed to 45 patients with high FNA-PTH values. The median largest diameter of the target parathyroid lesion identified by ultrasonography was 13 mm (range, 6 to 36). The median serum PTH level was 190 pg/mL (range, 78 to 1709; reference range, 15 to 65) whereas the median washout PTH was 2500 pg/mL (range, 480 to 3389). According to operative findings high FNA-PTH levels correctly identified parathyroid adenoma in 40 cases (89% of sensitivity and 100% of specificity and positive predictive value) whereas MIBI scan localized the lesion in 36 of these cases (80% of sensitivity). The higher level of PTH in preoperative ultrasound guided FNA washout is a considerable data to predict the correct localization of HP, particularly in circumstances of greater values than the serum PTH level. However, although its specificity is high, in cases of coexisting nodular thyroid disease, associated additional HP might be missed at focused parathyroidectomy

  16. Electropolymerization of pyrrole on oxidizable metal under high frequency ultrasound irradiation. Application of focused beam to a selective masking technique

    Energy Technology Data Exchange (ETDEWEB)

    Et Taouil, A. [Institut UTINAM, UMR 6213 CNRS, Universite de Franche-Comte, 30 Avenue de l' observatoire, 25009 Besancon Cedex (France); Lallemand, F., E-mail: fabrice.lallemand@univ-fcomte.f [Institut UTINAM, UMR 6213 CNRS, Universite de Franche-Comte, 30 Avenue de l' observatoire, 25009 Besancon Cedex (France); Hallez, L.; Hihn, J-Y. [Institut UTINAM, UMR 6213 CNRS, Universite de Franche-Comte, 30 Avenue de l' observatoire, 25009 Besancon Cedex (France)

    2010-12-01

    A novel masking technique against polymer deposition based on High Intensity Focused Ultrasound (HIFU) irradiation was developed for the first time. With this in mind, a variety of background salts were tested. Sodium salicylate was found to be the most effective electrolytic medium for pyrrole sonoelectropolymerization on copper as it leads to a very efficient passivating oxide layer preventing copper dissolution while enabling polymer formation independently from sonication. In such a medium, high frequency ultrasound greatly refines surface structure, and a slight increase in doping level is observed. Finally, it was proved that focused ultrasound increases copper dissolution in sodium oxalate electrolyte while preventing polypyrrole deposition. A selected zone on the copper substrate was thus irradiated by the focused ultrasound beam to protect it from polymerization. In a second stage, a self-assembled monolayer was deposited on this polymer-free area to create a surface biphased substrate. This type of masking technique can be proposed as an interesting alternative to lithography as it is easier to carry out and allows chemical waste reduction.

  17. Combined binary collision and continuum mechanics model applied to focused ion beam milling of a silicon membrane

    International Nuclear Information System (INIS)

    Hobler, Gerhard

    2015-01-01

    Many experiments indicate the importance of stress and stress relaxation upon ion implantation. In this paper, a model is proposed that is capable of describing ballistic effects as well as stress relaxation by viscous flow. It combines atomistic binary collision simulation with continuum mechanics. The only parameters that enter the continuum model are the bulk modulus and the radiation-induced viscosity. The shear modulus can also be considered but shows only minor effects. A boundary-fitted grid is proposed that is usable both during the binary collision simulation and for the spatial discretization of the force balance equations. As an application, the milling of a slit into an amorphous silicon membrane with a 30 keV focused Ga beam is studied, which demonstrates the relevance of the new model compared to a more heuristic approach used in previous work

  18. Characterization of nanometer-scale porosity in reservoir carbonate rock by focused ion beam-scanning electron microscopy.

    Science.gov (United States)

    Bera, Bijoyendra; Gunda, Naga Siva Kumar; Mitra, Sushanta K; Vick, Douglas

    2012-02-01

    Sedimentary carbonate rocks are one of the principal porous structures in natural reservoirs of hydrocarbons such as crude oil and natural gas. Efficient hydrocarbon recovery requires an understanding of the carbonate pore structure, but the nature of sedimentary carbonate rock formation and the toughness of the material make proper analysis difficult. In this study, a novel preparation method was used on a dolomitic carbonate sample, and selected regions were then serially sectioned and imaged by focused ion beam-scanning electron microscopy. The resulting series of images were used to construct detailed three-dimensional representations of the microscopic pore spaces and analyze them quantitatively. We show for the first time the presence of nanometer-scale pores (50-300 nm) inside the solid dolomite matrix. We also show the degree of connectivity of these pores with micron-scale pores (2-5 μm) that were observed to further link with bulk pores outside the matrix.

  19. Memory resistive switching in CeO2-based film microstructures patterned by a focused ion beam

    DEFF Research Database (Denmark)

    Velichko, A.; Boriskov, P.; Grishin, A.

    2014-01-01

    ) with insulating properties and a semiconducting ormetallic lowresistance state (ON) with resistance ratios up to 104. The influence of micro-scaling and defects formed at the cell boundaries during etching on its electrical characteristics has been analyzed. The appearance of a switching channel at the moment......Heteroepitaxial CeO2 (80 nm)/La0.5Sr0.5CoO3 (500 nm) film structure has been pulsed laser deposited on a sapphire substrate. The Ag/CeO2 microjunctions patterned by a focused ion beam on a La0.5Sr0.5CoO3 film exhibit reproducible reversible switching between a high resistance state (OFF...... of the electrical forming, responsible for the memory effect, has been proved, along with a mechanism of a self-healing electrical breakdown. © 2014 Elsevier B.V. All rights reserved....

  20. Simulation of self-focusing of laser beam through medium with multi-step photo-ionization

    International Nuclear Information System (INIS)

    Akaoka, Katsuaki; Wakaida, Ikuo; Arisawa, Takashi

    1995-01-01

    We built a computation code for the coupled nonlinear Maxwell-Density Matrix equations of multi-level atomic systems including transverse and time-dependent variations. Numerical solutions for two-level atomic systems shown as a function of laser detuning in Na and U are in good agreement with the experimental result. Applying this code to the laser beam propagation through medium with two-step photo-ionization, it is concluded that the group velocity in the spatial edge of a laser pulse is slower than that in the center, and the self-focusing and the temporal reshaping of the laser pulse used for the first-excitation are more distinguished than that used for ionization. (author)

  1. Direct fabrication of a W-C SNS Josephson junction using focused-ion-beam chemical vapour deposition

    International Nuclear Information System (INIS)

    Dai, Jun; Kometani, Reo; Ishihara, Sunao; Warisawa, Shin’ichi; Onomitsu, Koji; Krockenberger, Yoshiharu; Yamaguchi, Hiroshi

    2014-01-01

    A tungsten-carbide (W-C) superconductor/normal metal/superconductor (SNS) Josephson junction has been fabricated using focused-ion-beam chemical vapour deposition (FIB-CVD). Under certain process conditions, the component ratio has been tuned from W: C: Ga = 26%: 66%: 8% in the superconducting wires to W: C: Ga = 14%: 79%: 7% in the metallic junction. The critical current density at 2.5 K in the SNS Josephson junction is 1/3 of that in W-C superconducting nanowire. Also, a Fraunhofer-like oscillation of critical current in the junction with four periods is observed. FIB-CVD opens avenues for novel functional superconducting nanodevices. (paper)

  2. Dry fabrication of microdevices by the combination of focused ion beam and cryogenic deep reactive ion etching

    International Nuclear Information System (INIS)

    Chekurov, N; Tittonen, I; Grigoras, K; Sainiemi, L; Franssila, S; Peltonen, A

    2010-01-01

    In this paper, we demonstrate silicon microdevice fabrication by a combination of focused ion beam (FIB) and cryogenic deep reactive ion etching (DRIE). Applying FIB treatment only to a thin surface layer enables very high writing speed compared with FIB milling. The use of DRIE then defines the micro- and nanodevices utilizing the FIB-modified silicon as a mask. We demonstrate the ability to create patterns on highly 3D structures, which is extremely challenging by other nanofabrication methods. The alignment of optically made and FIB-defined patterns is also demonstrated. We also show that complete microelectromechanical systems (MEMS) can be fabricated by this method by presenting a double-ended tuning fork resonator as an example. Extremely short process time is achieved as the full fabrication cycle from mask design to electrical measurements can be completed during one working day.

  3. Fabrication of low-loss silicon-on-oxidized-porous-silicon strip waveguide using focused proton-beam irradiation.

    Science.gov (United States)

    Teo, E J; Bettiol, A A; Yang, P; Breese, M B H; Xiong, B Q; Mashanovich, G Z; Headley, W R; Reed, G T

    2009-03-01

    We have successfully fabricated low-loss silicon-on-oxidized-porous-silicon (SOPS) strip waveguides with high-index contrast using focused proton-beam irradiation and electrochemical etching. Smooth surface quality with rms roughness of 3.1 nm is achieved for a fluence of 1x10(15)/cm(2) after postoxidation treatment. Optical characterization at a wavelength of 1550 nm shows a loss of 1.1+/-0.4 dB/cm and 1.2+/-0.4 dB/cm in TE and TM polarization respectively, which we believe is the lowest reported loss for SOPS waveguides. This opens up new opportunities for all-silicon-based optoelectronics applications.

  4. Skeletal muscle triad junction ultrastructure by Focused-Ion-Beam milling of muscle and Cryo-Electron Tomography.

    Science.gov (United States)

    Wagenknecht, Terence; Hsieh, Chyongere; Marko, Michael

    Cryo-electron tomography (cryo-ET) has emerged as perhaps the only practical technique for revealing nanometer-level three-dimensional structural details of subcellular macromolecular complexes in their native context, inside the cell. As currently practiced, the specimen should be 0.1- 0.2 microns in thickness to achieve optimal resolution. Thus, application of cryo-ET to intact frozen (vitreous) tissues, such as skeletal muscle, requires that they be sectioned. Cryo-ultramicrotomy is notoriously difficult and artifact-prone when applied to frozen cells and tissue, but a new technique, focused ion beam milling (cryo-FIB), shows great promise for "thinning" frozen biological specimens. Here we describe our initial results in applying cryo-FIB and cryo-ET to triad junctions of skeletal muscle.

  5. The field emission properties of high aspect ratio diamond nanocone arrays fabricated by focused ion beam milling

    Directory of Open Access Journals (Sweden)

    Z.L. Wang, Q. Wang, H.J. Li, J.J. Li, P. Xu, Q. Luo, A.Z. Jin, H.F. Yang and C.Z. Gu

    2005-01-01

    Full Text Available High aspect ratio diamond nanocone arrays are formed on freestanding diamond film by means of focused ion beam (FIB milling technology and hot-filament chemical vapor deposition (HFCVD method. The structure and phase purity of an individual diamond nanocone are characterized by scanning electron microscopy (SEM and micro-Raman spectroscopy. The result indicates that the diamond cones with high aspect ratio and small tip apex radius can be obtained by optimizing the parameters of FIB milling and diamond growth. The diamond nanocone arrays were also used to study the electron field emission properties and electric field shielding effect, finding high emission current density, low threshold and weak shielding effect, all attributable to the high field enhancement factor and suitable cone density of the diamond nanocone emitter

  6. Tight focusing of a radially polarized Laguerre–Bessel–Gaussian beam and its application to manipulation of two types of particles

    International Nuclear Information System (INIS)

    Nie, Zhongquan; Shi, Guang; Li, Dongyu; Zhang, Xueru; Wang, Yuxiao; Song, Yinglin

    2015-01-01

    The intensity distributions near the focus for radially polarized Laguerre–Bessel–Gaussian beams by a high numerical aperture objective in the immersion liquid are computed based on the vector diffraction theory. We compare the focusing properties of the radially polarized Laguerre–Bessel–Gaussian beams with those of Laguerre–Gaussian and Bessel–Gaussian modes. Furthermore, the effects of the optimally designed concentric three-zone phase filters on the intensity profiles in the focal region are examined. We further analyze the radiation forces on Rayleigh particles produced by the highly focused radially polarized Laguerre–Bessel–Gaussian beams using the specially engineered three-zone phase filters. - Highlights: • The tightly focusing of radially polarized LBG beams is examined. • The focusing performances of LBG beams are preferable over that of LG and BG modes. • A bright spot and an optical cage can be formed by special phase modulation. • These special focusing patterns can stably manipulate two types of particles

  7. Cone beam computed tomography in implant dentistry: a systematic review focusing on guidelines, indications, and radiation dose risks.

    Science.gov (United States)

    Bornstein, Michael M; Scarfe, William C; Vaughn, Vida M; Jacobs, Reinhilde

    2014-01-01

    The aim of the paper is to identify, review, analyze, and summarize available evidence in three areas on the use of cross-sectional imaging, specifically maxillofacial cone beam computed tomography (CBCT) in pre- and postoperative dental implant therapy: (1) Available clinical use guidelines, (2) indications and contraindications for use, and (3) assessment of associated radiation dose risk. Three focused questions were developed to address the aims. A systematic literature review was performed using a PICO-based search strategy based on MeSH key words specific to each focused question of English-language publications indexed in the MEDLINE database retrospectively from October 31, 2012. These results were supplemented by a hand search and gray literature search. Twelve publications were identified providing guidelines for the use of cross-sectional radiography, particularly CBCT imaging, for the pre- and/or postoperative assessment of potential dental implant sites. The publications discovered by the PICO strategy (43 articles), hand (12), and gray literature searches (1) for the second focus question regarding indications and contraindications for CBCT use in implant dentistry were either cohort or case-controlled studies. For the third question on the assessment of associated radiation dose risk, a total of 22 articles were included. Publication characteristics and themes were summarized in tabular format. The reported indications for CBCT use in implant dentistry vary from preoperative analysis regarding specific anatomic considerations, site development using grafts, and computer-assisted treatment planning to postoperative evaluation focusing on complications due to damage of neurovascular structures. Effective doses for different CBCT devices exhibit a wide range with the lowest dose being almost 100 times less than the highest dose. Significant dose reduction can be achieved by adjusting operating parameters, including exposure factors and reducing the

  8. Stability of an emittance-dominated sheet-electron beam in planar wiggler and periodic permanent magnet structures with natural focusing

    Directory of Open Access Journals (Sweden)

    B. E. Carlsten

    2005-06-01

    Full Text Available A sheet-beam traveling-wave amplifier has been proposed as a high-power generator of rf from 95 to 300 GHz, using a microfabricated rf slow-wave structure [Carlsten et al., IEEE Trans. Plasma Sci. 33, 85 (2005ITPSBD0093-381310.1109/TPS.2004.841172], for emerging radar and communications applications. The planar geometry of microfabrication technologies matches well with the nearly planar geometry of a sheet beam, and the greater allowable beam current leads to high-peak power, high-average power, and wide bandwidths. Simulations of nominal designs using a vane-loaded waveguide as the slow-wave structure have indicated gains in excess of 1   dB/mm, with extraction efficiencies greater than 20% at 95 GHz with a 120-kV, 20-A electron beam. We have identified stable sheet-beam formation and transport as the key enabling technology for this type of device. In this paper, we describe sheet-beam transport, for both wiggler and periodic permanent magnet (PPM magnetic field configurations, with natural (or single-plane focusing. For emittance-dominated transport, the transverse equation of motion reduces to a Mathieu equation, and to a modified Mathieu equation for a space-charge dominated beam. The space-charge dominated beam has less beam envelope ripple than an emittance-dominated beam, but they have similar stability thresholds (defined by where the beam ripple continues to grow without bound along the transport line, consistent with the threshold predicted by the Mathieu equation. Design limits are derived for an emittance-dominated beam based on the Mathieu stability threshold. The increased beam envelope ripple for emittance-dominated transport may impact these design limits, for some transport requirements. The stability of transport in a wiggler field is additionally compromised by the beam’s increased transverse motion. Stable sheet-beam transport with natural focusing is shown to be achievable for a 120-kV, 20-A, elliptical beam with

  9. Networks of ultra-fine Ag nanocrystals in a Teflon AF (registered) matrix by vapour phase e-beam-assisted deposition

    International Nuclear Information System (INIS)

    Biswas, A; Bayer, I S; Marken, B; Pounds, T D; Norton, M G

    2007-01-01

    We have fabricated nanocomposite thin films comprising silver (Ag) nanoparticles dispersed in a Teflon AF (registered) polymer matrix using electron-beam-assisted physical vapour deposition. Four different Ag nanoparticle volume fillings (20%, 35%, 70% and 75%) were achieved by varying the relative metal-polymer evaporation rates with the formation of highly crystalline Ag nanoparticles regardless of the filling ratio. The present fabrication technique allowed full control over dispersion uniformity of nanoparticles in the polymer network. At 20% and 35% metal volume fillings, the nanocomposite film morphology consists of a uniformly dispersed assembly of equiaxed isolated Ag nanoparticles. At higher metal volume fractions the nanocomposite structures displayed two different and unique Ag nanoparticle arrangements within the polymer matrix. In particular, at 70% metal filling, the formation of irregularly shaped clusters of individually assembled nanocrystals was observed. At a slightly higher volume filling (75%), larger irregularly shaped Ag nanocrystals that appeared to be the result of coalescence and grain growth were observed. Finally, a composite theory developed by Tandon and Weng was used to estimate various elastic properties of the nanocomposite films. At high metal filling, the reinforcing effect of the Ag nanoparticles was reflected as approximately a sixfold increase in the elastic modulus compared to the virgin polymer film. Possible applications of such ultra-fine metal nanoparticles networks are discussed

  10. Development of high-polarization Fe/Ge neutron polarizing supermirror: Possibility of fine-tuning of scattering length density in ion beam sputtering

    Science.gov (United States)

    Maruyama, R.; Yamazaki, D.; Akutsu, K.; Hanashima, T.; Miyata, N.; Aoki, H.; Takeda, M.; Soyama, K.

    2018-04-01

    The multilayer structure of Fe/Si and Fe/Ge systems fabricated by ion beam sputtering (IBS) was investigated using X-ray and polarized neutron reflectivity measurements and scanning transmission electron microscopy with energy-dispersive X-ray analysis. The obtained result revealed that the incorporation of sputtering gas particles (Ar) in the Ge layer gives rise to a marked reduction in the neutron scattering length density (SLD) and contributes to the SLD contrast between the Fe and Ge layers almost vanishing for spin-down neutrons. Bundesmann et al. (2015) have shown that the implantation of primary Ar ions backscattered at the target is responsible for the incorporation of Ar particles and that the fraction increases with increasing ion incidence angle and increasing polar emission angle. This leads to a possibility of fine-tuning of the SLD for the IBS, which is required to realize a high polarization efficiency of a neutron polarizing supermirror. Fe/Ge polarizing supermirror with m = 5 fabricated under the same condition showed a spin-up reflectivity of 0.70 at the critical momentum transfer. The polarization was higher than 0.985 for the qz range where the correction for the polarization inefficiencies of the beamline works properly. The result of the polarized neutron reflectivity measurement suggests that the "magnetically-dead" layers formed at both sides of the Fe layer, together with the SLD contrast, play a critical role in determining the polarization performance of a polarizing supermirror.

  11. Near edge X-ray absorption fine structure study for optimization of hard diamond-like carbon film formation with Ar cluster ion beam

    CERN Document Server

    Kitagawa, T; Kanda, K; Shimizugawa, Y; Toyoda, N; Matsui, S; Yamada, I; Tsubakino, H; Matsuo, J

    2003-01-01

    Diamond-like carbon (DLC) film deposited using C sub 6 sub 0 vapor with simultaneous irradiation of an Ar cluster ion beam was characterized by a near edge X-ray absorption fine structure (NEXAFS), in order to optimize the hard DLC film deposition conditions. Contents of sp sup 2 orbitals in the films, which were estimated from NEXAFS spectra, are 30% lower than that of a conventional DLC film deposited by a RF plasma method. Those contents were obtained under the flux ratio of the C sub 6 sub 0 molecules to the Ar cluster ions to range from 1 to 20, at 5keV of Ar cluster ion acceleration energy. Average hardness of the films was 50 GPa under these flux ratios. This hardness was three times higher than that of a conventional DLC film. Furthermore, the lowest sp sup 2 content and above-mentioned high hardness were obtained at room temperature of the substrate when the depositions were performed in the range of the substrate temperature from room temperature to 250degC. (author)

  12. Focused Ion Beam Implantation

    Science.gov (United States)

    1992-03-17

    vernier structures in PMMA aligned to vernier structures previously fabricated on the sample in both the x and y axis. Some of this work is described in...length of the order of micrometers . Electrons at an energy of 50 keV were used, and a minimum As a variation from the ordinary single-gate MODFET, we

  13. A continuous plasma final focus

    International Nuclear Information System (INIS)

    Whittum, D.H.

    1989-11-01

    Scaling laws are set down for a plasma cell used for transport, focusing and current neutralization of fine, intense, relativistic electron beams. It is found that there exists a minimum beam spot size, σ min ∼ var-epsilon n (I A /γI) 1/2 , in such a focusing system. Propagation issues, including channel formation, synchrotron radiation, beam ionization and instabilities, are discussed. Numerical examples are given for a proof-of-principle experiment at KEK, an application for luminosity enhancement at the SLC, and a hypothetical TeV electron-positron collider. For a TeV collider, it is found that the effect of ion-motion on focusing, and the effect of Buneman instability on current neutralization must be considered. 3 figs., 1 tab

  14. SU-E-T-230: Creating a Large Number of Focused Beams with Variable Patient Head Tilt to Improve Dose Fall-Off for Brain Radiosurgery

    International Nuclear Information System (INIS)

    Chiu, J; Ma, L

    2015-01-01

    Purpose: To develop a treatment delivery and planning strategy by increasing the number of beams to minimize dose to brain tissue surrounding a target, while maximizing dose coverage to the target. Methods: We analyzed 14 different treatment plans via Leksell PFX and 4C. For standardization, single tumor cases were chosen. Original treatment plans were compared with two optimized plans. The number of beams was increased in treatment plans by varying tilt angles of the patient head, while maintaining original isocenter and the beam positions in the x-, y- and z-axes, collimator size, and beam blocking. PFX optimized plans increased beam numbers with three pre-set tilt angles, 70, 90, 110, and 4C optimized plans increased beam numbers with tilt angles increasing arbitrarily from range of 30 to 150 degrees. Optimized treatment plans were compared dosimetrically with original treatment plans. Results: Comparing total normal tissue isodose volumes between original and optimized plans, the low-level percentage isodose volumes decreased in all plans. Despite the addition of multiple beams up to a factor of 25, beam-on times for 1 tilt angle versus 3 or more tilt angles were comparable (<1 min.). In 64% (9/14) of the studied cases, the volume percentage decrease by >5%, with the highest value reaching 19%. The addition of more tilt angles correlates to a greater decrease in normal brain irradiated volume. Selectivity and coverage for original and optimized plans remained comparable. Conclusion: Adding large number of additional focused beams with variable patient head tilt shows improvement for dose fall-off for brain radiosurgery. The study demonstrates technical feasibility of adding beams to decrease target volume

  15. Neutron powder diffraction of small-volume samples at high pressure using compact opposed-anvil cells and focused beam

    International Nuclear Information System (INIS)

    Okuchi, T; Sasaki, S; Ohno, Y; Abe, J; Osakabe, T; Hattori, T; Sano-Furukawa, A; Utsumi, W; Arima, H; Harjo, S; Ito, T; Aizawa, K; Komatsu, K; Kagi, H

    2012-01-01

    Neutron powder diffraction techniques of small-volume samples at high pressure using compact opposed-anvil cells were developed at J-PARC pulsed neutron source. For this purpose we apply a few types of super-hard materials as opposed anvils with culet diameters between 3 to 5 mm. Generated pressures with these anvils were up to 9 GPa for 2 to 4 mm 3 and up to 14 GPa for 0.7 mm 3 sample volumes, which not only depends on the anvil geometry and material but even more depends on the metallic gasket geometry and material. A representative anvil geometry with 4 mm in culet diameter, along with TiZr 'null alloy' metallic gasket containing varying sample volumes, were then applied to time-of-flight neutron powder diffraction experiments, where methane hydrate of 4 mm 3 volume and lead of 0.7 mm 3 volume were separately measured and their signal-to-background ratios were evaluated. A neutron-focusing optics was used to concentrate the neutron beam into these small-volume samples to increase the intensity of diffraction. Although spurious diffraction peaks from the anvils were prominent, more than seven diffraction peaks are clearly observed from both of the samples. In spite of the smaller sample capacity than previous standard high-pressure apparatus for neutron, it is concluded that the opposed-anvil cells will become alternative apparatuses for neutron scattering at strong pulsed neutron sources where sufficient neutron intensity was granted.

  16. A method of determining acoustical physical constants for piezoelectric materials by line-focus-beam acoustic microscopy.

    Science.gov (United States)

    Takanaga, Izumi; Kushibiki, Jun-ichi

    2002-07-01

    We developed a new method of determining acoustical physical constants (elastic constant, piezoelectric constant, dielectric constant, and density) of piezoelectric materials with high accuracy. This method acquires velocities of leaky surface acoustic waves (LSAWs) excited on the water-loaded specimen surface, measured by line-focus-beam (LFB) acoustic microscopy, and bulk velocities of longitudinal and shear waves, measured with plane-wave transducers replacing the LFB device in the same system, together with the dielectric constants and density measured independently, for a small number of specimens. For LiNbO3 and LiTaO3 crystals, we demonstrated that we could accurately determine the constants by choosing proper propagation directions of LSAWs and bulk waves for three principal X-, Y-, and Z-cut specimens and one rotated Y-cut specimen [(104) plate for LiNbO3 and (012) plate for LiTaOa]. The accuracy is nearly the same as that for the constants determined only from the bulk wave velocities.

  17. 3D Plant cell architecture of Arabidopsis thaliana (Brassicaceae) using focused ion beam-scanning electron microscopy.

    Science.gov (United States)

    Bhawana; Miller, Joyce L; Cahoon, A Bruce

    2014-06-01

    Focused ion beam-scanning electron microscopy (FIB-SEM) combines the ability to sequentially mill the sample surface and obtain SEM images that can be used to create 3D renderings with micron-level resolution. We have applied FIB-SEM to study Arabidopsis cell architecture. The goal was to determine the efficacy of this technique in plant tissue and cellular studies and to demonstrate its usefulness in studying cell and organelle architecture and distribution. • Seed aleurone, leaf mesophyll, stem cortex, root cortex, and petal lamina from Arabidopsis were fixed and embedded for electron microscopy using protocols developed for animal tissues and modified for use with plant cells. Each sample was sectioned using the FIB and imaged with SEM. These serial images were assembled to produce 3D renderings of each cell type. • Organelles such as nuclei and chloroplasts were easily identifiable, and other structures such as endoplasmic reticula, lipid bodies, and starch grains were distinguishable in each tissue. • The application of FIB-SEM produced 3D renderings of five plant cell types and offered unique views of their shapes and internal content. These results demonstrate the usefulness of FIB-SEM for organelle distribution and cell architecture studies.

  18. Effect of polyglycerol esters additive on palm oil crystallization using focused beam reflectance measurement and differential scanning calorimetry.

    Science.gov (United States)

    Saw, M H; Hishamuddin, E; Chong, C L; Yeoh, C B; Lim, W H

    2017-01-01

    The effect of 0.1-0.7% (w/w) of polyglycerol esters (PGEmix-8) on palm oil crystallization was studied using focused beam reflectance measurement (FBRM) to analyze the in-line changes of crystal size distribution during the crystallization. FBRM results show that 0.1-0.5% (w/w) of PGEmix-8 did not significantly affect nucleation but slightly retarded crystal growth. The use of 0.7% (w/w) additive showed greater heterogeneous nucleation compared to those with lower dosages of additive. Crystal growth was also greatly reduced when using 0.7% (w/w) dosage. The morphological study indicated that the palm oil crystals were smaller and more even in size than when more additive was added. Isothermal crystallization studies using differential scanning calorimetry (DSC) showed increased inhibitory effects on palm oil crystal growth with increasing concentration of PGEmix-8. These results imply that PGEmix-8 is a nucleation enhancing and crystal growth retarding additive in palm oil crystallization at 0.7% (w/w) dosage. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  19. Characterisation of edgeless technologies for pixellated and strip silicon detectors with a micro-focused X-ray beam

    Science.gov (United States)

    Bates, R.; Blue, A.; Christophersen, M.; Eklund, L.; Ely, S.; Fadeyev, V.; Gimenez, E.; Kachkanov, V.; Kalliopuska, J.; Macchiolo, A.; Maneuski, D.; Phlips, B. F.; Sadrozinski, H. F.-W.; Stewart, G.; Tartoni, N.; Zain, R. M.

    2013-01-01

    Reduced edge or ``edgeless'' detector design offers seamless tileability of sensors for a wide range of applications from particle physics to synchrotron and free election laser (FEL) facilities and medical imaging. Combined with through-silicon-via (TSV) technology, this would allow reduced material trackers for particle physics and an increase in the active area for synchrotron and FEL pixel detector systems. In order to quantify the performance of different edgeless fabrication methods, 2 edgeless detectors were characterized at the Diamond Light Source using an 11 μm FWHM 15 keV micro-focused X-ray beam. The devices under test were: a 150 μm thick silicon active edge pixel sensor fabricated at VTT and bump-bonded to a Medipix2 ROIC; and a 300 μm thick silicon strip sensor fabricated at CIS with edge reduction performed by SCIPP and the NRL and wire bonded to an ALiBaVa readout system. Sub-pixel resolution of the 55 μm active edge pixels was achieved. Further scans showed no drop in charge collection recorded between the centre and edge pixels, with a maximum deviation of 5% in charge collection between scanned edge pixels. Scans across the cleaved and standard guard ring edges of the strip detector also show no reduction in charge collection. These results indicate techniques such as the scribe, cleave and passivate (SCP) and active edge processes offer real potential for reduced edge, tiled sensors for imaging detection applications.

  20. Charging suppression in focused-ion beam fabrication of visible subwavelength dielectric grating reflector using electron conducting polymer

    KAUST Repository

    Alias, Mohd Sharizal

    2015-08-19

    Nanoscale periodic patterning on insulating materials using focused-ion beam (FIB) is challenging because of charging effect, which causes pattern distortion and resolution degradation. In this paper, the authors used a charging suppression scheme using electron conducting polymer for the implementation of FIB patterned dielectric subwavelength grating (SWG) reflector. Prior to the FIB patterning, the authors numerically designed the optimal structure and the fabrication tolerance for all grating parameters (period, grating thickness, fill-factor, and low refractive index layer thickness) using the rigorous-coupled wave analysis computation. Then, the authors performed the FIB patterning on the dielectric SWG reflector spin-coated with electron conducting polymer for the anticharging purpose. They also performed similar patterning using thin conductive film anticharging scheme (30 nm Cr coating) for comparison. Their results show that the electron conducting polymer anticharging scheme effectively suppressing the charging effect during the FIB patterning of dielectric SWG reflector. The fabricated grating exhibited nanoscale precision, high uniformity and contrast, constant patterning, and complied with fabrication tolerance for all grating parameters across the entire patterned area. Utilization of electron conducting polymer leads to a simpler anticharging scheme with high precision and uniformity for FIB patterning on insulator materials.

  1. Optimized cryo-focused ion beam sample preparation aimed at in situ structural studies of membrane proteins.

    Science.gov (United States)

    Schaffer, Miroslava; Mahamid, Julia; Engel, Benjamin D; Laugks, Tim; Baumeister, Wolfgang; Plitzko, Jürgen M

    2017-02-01

    While cryo-electron tomography (cryo-ET) can reveal biological structures in their native state within the cellular environment, it requires the production of high-quality frozen-hydrated sections that are thinner than 300nm. Sample requirements are even more stringent for the visualization of membrane-bound protein complexes within dense cellular regions. Focused ion beam (FIB) sample preparation for transmission electron microscopy (TEM) is a well-established technique in material science, but there are only few examples of biological samples exhibiting sufficient quality for high-resolution in situ investigation by cryo-ET. In this work, we present a comprehensive description of a cryo-sample preparation workflow incorporating additional conductive-coating procedures. These coating steps eliminate the adverse effects of sample charging on imaging with the Volta phase plate, allowing data acquisition with improved contrast. We discuss optimized FIB milling strategies adapted from material science and each critical step required to produce homogeneously thin, non-charging FIB lamellas that make large areas of unperturbed HeLa and Chlamydomonas cells accessible for cryo-ET at molecular resolution. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Magnetic properties of optimized cobalt nanospheres grown by focused electron beam induced deposition (FEBID on cantilever tips

    Directory of Open Access Journals (Sweden)

    Soraya Sangiao

    2017-10-01

    Full Text Available In this work, we present a detailed investigation of the magnetic properties of cobalt nanospheres grown on cantilever tips by focused electron beam induced deposition (FEBID. The cantilevers are extremely soft and the cobalt nanospheres are optimized for magnetic resonance force microscopy (MRFM experiments, which implies that the cobalt nanospheres must be as small as possible while bearing high saturation magnetization. It was found that the cobalt content and the corresponding saturation magnetization of the nanospheres decrease for nanosphere diameters less than 300 nm. Electron holography measurements show the formation of a magnetic vortex state in remanence, which nicely agrees with magnetic hysteresis loops performed by local magnetometry showing negligible remanent magnetization. As investigated by local magnetometry, optimal behavior for high-resolution MRFM has been found for cobalt nanospheres with a diameter of ≈200 nm, which present atomic cobalt content of ≈83 atom % and saturation magnetization of 106 A/m, around 70% of the bulk value. These results represent the first comprehensive investigation of the magnetic properties of cobalt nanospheres grown by FEBID for application in MRFM.

  3. Laser-assisted atom probe tomography of semiconductors: The impact of the focused-ion beam specimen preparation.

    Science.gov (United States)

    Bogdanowicz, J; Kumar, A; Fleischmann, C; Gilbert, M; Houard, J; Vella, A; Vandervorst, W

    2018-03-05

    This paper demonstrates the increased light absorption efficiency of semiconducting atom probe tips resulting from focused-ion-beam (FIB) preparation. We use transmission electron microscopy to show that semiconducting tips prepared with FIB are surrounded with an amorphized shell. Photomodulated optical reflectance measurements then provide evidence that FIB-induced damage leads to an increase in both sub- and supra-bandgap light absorption efficiency. Using laser-assisted atom probe tomography (La-APT) measurements, we finally show that, for a nanoscale tip geometry, the laser-induced heating of a tip during La-APT is enhanced by the FIB preparation. We conclude that, upon supra-bandgap illumination, the presence of a FIB-amorphized surface dramatically increases the light-induced heat generation inside semiconducting tips during La-APT. Furthermore, we also deduce that, in the intriguing case of sub-bandgap illumination, the amorphization plays a crucial role in the unexpected light absorption. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Metal-insulator transition in Pt-C nanowires grown by focused-ion-beam-induced deposition

    International Nuclear Information System (INIS)

    Fernandez-Pacheco, A.; Ibarra, M. R.; De Teresa, J. M.; Cordoba, R.

    2009-01-01

    We present a study of the transport properties of Pt-C nanowires created by focused-ion-beam (FIB)-induced deposition. By means of the measurement of the resistance while the deposit is being performed, we observe a progressive decrease in the nanowire resistivity with thickness, changing from 10 8 μΩ cm for thickness ∼20 nm to a lowest saturated value of 700 μΩ cm for thickness >150 nm. Spectroscopy analysis indicates that this dependence on thickness is caused by a gradient in the metal-carbon ratio as the deposit is grown. We have fabricated nanowires in different ranges of resistivity and studied their conduction mechanism as a function of temperature. A metal-insulator transition as a function of the nanowire thickness is observed. The results will be discussed in terms of the Mott-Anderson theory for noncrystalline materials. An exponential decrease in the conductance with the electric field is found for the most resistive samples, a phenomenon understood by the theory of hopping in lightly doped semiconductors under strong electric fields. This work explains the important discrepancies found in the literature for Pt-C nanostructures grown by FIB and opens the possibility to tune the transport properties of this material by an appropriate selection of the growth parameters.

  5. Stabilization of Nanometre-Size Particle Beams in the Final Focus System of the Compact LInear Collider (CLIC)

    CERN Document Server

    Redaelli, S

    2003-01-01

    The Compact LInear Collider (CLIC) study at the European Organization for Nuclear Research (CERN) is developing the design of a 3 TeV e+ e- linear collider. The discovery reach of this machine depends on obtaining a luminosity of 1035 cm_2s_1, which will be done by colliding beams with transverse spot sizes in the nanometre range ≈ 60 × 0:7 nm2). Tolerances on fast mechanical stability of the focusing quadrupoles reach the 0.2 nm level. The serious concern of magnet stabilization for future linear colliders has been addressed by building a CERN test stand on magnet stability, bringing together state-of-the-art stabilization technology, latest equipment for vibration measurements and realistic magnet prototypes. For the first time an accelerator magnet was successfully stabilized to the sub-nanometre level, reducing its vibrations level by one order of magnitude with respect to the supporting ground. The best measurements indicate transverse RMS vibration amplitudes (above 4 Hz) of (0.79+0.08) nm ho...

  6. Focused beam reflectance method as an innovative (PAT) tool to monitor in-line granulation process in fluidized bed.

    Science.gov (United States)

    Alshihabi, Firas; Vandamme, Thierry; Betz, Gabriele

    2013-02-01

    Fluidized bed granulation is a commonly used unit operation in the pharmaceutical industry. But still to obtain and control the desired granule size is challenging due to many process variables affecting the final product. Focused beam reflectance measurement (FBRM, Mettler-Toledo, Switzerland) is an increasingly popular particle growth analysis technique. FBRM tool was installed in two different locations inside a fluidized bed granulator (GPCG2, Glatt, Binzen) in order to monitor the granulation growth kinetics. An experimental design was created to study the effect of process variables using FBRM probe and comparing the results with the one's measured by sieve analysis. The probe location is of major importance to get smooth and robust curves. The excess feeding of binder solution might lead to agglomeration and thus to process collapse, however this phenomenon was clearly detected with FBRM method. On the other hand, the process variables at certain levels might affect the FBRM efficiency by blocking the probe window with sticky particles. A good correlation was obtained (R(2) = 0.95) between FBRM and sieve analysis mean particle size. The proposed in-line monitoring tool enables the operator to select appropriate process parameters and control the wet granulation process more efficiently.

  7. Three-dimensional ultrastructure of osteocytes assessed by focused ion beam-scanning electron microscopy (FIB-SEM).

    Science.gov (United States)

    Hasegawa, Tomoka; Yamamoto, Tomomaya; Hongo, Hiromi; Qiu, Zixuan; Abe, Miki; Kanesaki, Takuma; Tanaka, Kawori; Endo, Takashi; de Freitas, Paulo Henrique Luiz; Li, Minqi; Amizuka, Norio

    2018-02-09

    The aim of this study is to demonstrate the application of focused ion beam-scanning electron microscopy, FIB-SEM for revealing the three-dimensional features of osteocytic cytoplasmic processes in metaphyseal (immature) and diaphyseal (mature) trabeculae. Tibiae of eight-week-old male mice were fixed with aldehyde solution, and treated with block staining prior to FIB-SEM observation. While two-dimensional backscattered SEM images showed osteocytes' cytoplasmic processes in a fragmented fashion, three-dimensional reconstructions of FIB-SEM images demonstrated that osteocytes in primary metaphyseal trabeculae extended their cytoplasmic processes randomly, thus maintaining contact with neighboring osteocytes and osteoblasts. In contrast, diaphyseal osteocytes extended thin cytoplasmic processes from their cell bodies, which ran perpendicular to the bone surface. In addition, these osteocytes featured thick processes that branched into thinner, transverse cytoplasmic processes; at some point, however, these transverse processes bend at a right angle to run perpendicular to the bone surface. Osteoblasts also possessed thicker cytoplasmic processes that branched off as thinner processes, which then connected with cytoplasmic processes of neighboring osteocytes. Thus, FIB-SEM is a useful technology for visualizing the three-dimensional structures of osteocytes and their cytoplasmic processes.

  8. Practical workflow for cryo focused-ion-beam milling of tissues and cells for cryo-TEM tomography.

    Science.gov (United States)

    Hsieh, Chyongere; Schmelzer, Thomas; Kishchenko, Gregory; Wagenknecht, Terence; Marko, Michael

    2014-01-01

    Vitreous freezing offers a way to study cells and tissue in a near-native state by cryo-transmission electron microscopy (cryo-TEM), which is important when structural information at the macromolecular level is required. Many cells - especially those in tissue - are too thick to study intact in the cryo-TEM. Cryo focused-ion-beam (cryo-FIB) milling is being used in a few laboratories to thin vitreously frozen specimens, thus avoiding the artifacts and difficulties of cryo-ultramicrotomy. However, the technique is challenging because of the need to avoid devitrification and frost accumulation during the entire process, from the initial step of freezing to the final step of loading the specimen into the cryo-TEM. We present a robust workflow that makes use of custom fixtures and devices that can be used for high-pressure-frozen bulk tissue samples as well as for samples frozen on TEM grids. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. Focused-ion-beam overlay-patterning of three-dimensional diamond structures for advanced single-photon properties

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Qianqing; Liu, Dongqi; Liu, Gangqin; Chang, Yanchun; Li, Wuxia, E-mail: liwuxia@aphy.iphy.ac.cn, E-mail: czgu@aphy.iphy.ac.cn [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Pan, Xinyu; Gu, Changzhi, E-mail: liwuxia@aphy.iphy.ac.cn, E-mail: czgu@aphy.iphy.ac.cn [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100190 (China)

    2014-07-28

    Sources of single photons are of fundamental importance in many applications as to provide quantum states for quantum communication and quantum information processing. Color centers in diamond are prominent candidates to generate and manipulate quantum states of light, even at room temperature. However, the efficiency of photon collection of the color centers in bulk diamond is greatly reduced by refraction at the diamond/air interface. To address this issue, diamond structuring has been investigated by various methods. Among them, focused-ion-beam (FIB) direct patterning has been recognized as the most favorable technique. But it has been noted that diamond tends to present significant challenges in FIB milling, e.g., the susceptibility of forming charging related artifacts and topographical features. In this work, periodically-positioned-rings and overlay patterning with stagger-superimposed-rings were proposed to alleviate some problems encountered in FIB milling of diamond, for improved surface morphology and shape control. Cross-scale network and uniform nanostructure arrays have been achieved in single crystalline diamond substrates. High quality diamond solid immersion lens and nanopillars were sculptured with a nitrogen-vacancy center buried at the desired position. Compared with the film counterpart, an enhancement of about ten folds in single photon collection efficiency was achieved with greatly improved signal to noise ratio. All these results indicate that FIB milling through over-lay patterning could be an effective approach to fabricate diamond structures, potentially for quantum information studies.

  10. Characterization of the onset asphaltenes by focused-beam laser reflectance : a tool for chemical additives screening

    Energy Technology Data Exchange (ETDEWEB)

    Marugan, J.; Calles, J.A.; Dufour, J.; Gimenez-Aguirre, R. [Univ. Rey Juan Carlos, Madrid (Spain). URJC-Repsol-YPF Flow Assurance Laboratory, Dept. of Chemical and Environmental Technology; Pena, J.L. [Univ. Rey Juan Carlos, Madrid (Spain). URJC-Repsol-YPF Flow Assurance Laboratory, Dept. of Chemical and Environmental Technology; Centro Tecnologico Repsol-YPF, Madrid (Spain); Merino-Garcia, D. [Centro Tecnologico Repsol-YPF, Madrid (Spain)

    2008-07-01

    The deposition of asphaltenes in crude oil can cause flow assurance problems. In this study, a laser reflectance technique known as Focused-Beam Reflectance Measurement (FBRM) was used to study the kinetics of asphaltenes aggregation near onset. The FBRM tool provides a very sensitive way of determining the onset n-alkane/oil mass ratio. The influence of the n-alkane solvent and temperature on the solvent/oil threshold ratio of 2 South American crude oils with 21 and 27 API were investigated. The FBRM technique provided kinetic information about the evolution with time of the size distribution of asphaltenes flocs. Additional FBRM experiments of asphaltene redissolution and reprecipitation were also performed for a comparative evaluation, beginning with the solids recovered following the IP- 143 standard, which were fractionated into 4 different polarity groups using n-pentane - chloroform mixtures. The objective was to find correlations between polarity of the asphaltenes and its instability near the onset. Metal content was determined through atomic emission spectroscopy. The solids were characterized by 1H NMR, FT-IR spectroscopy, and vapour-pressure osmometry in order to determine the chemical and structural features of the most unstable asphaltenes. The FBRM probe was used to screen commercial chemical additives to prevent asphaltenes deposits. This technique was shown to be a very powerful tool for examining the influence of additives on the aggregation kinetics and the particle size distribution of the first asphaltene solids.

  11. Generation and focusing of pulsed intense ion beams. Final progress report, April 1, 1979-September 30, 1979

    International Nuclear Information System (INIS)

    Sudan, R.N.; Hammer, D.A.

    1981-04-01

    Theoretical calculations suggest that an intense pulsed approx. 1 MeV proton beam can be used to simulate the characteristics of approx. 1 GeV heavy ion beam propagation in an inertial confinement fusion reactor chamber. Given the present availability of the former beams and the high projected cost for obtaining the latter ones, such experimental simulations appear appropriate. Work was undertaken under the cited contract to apply the technology of intense proton beams to this end. The first task was the development of a high brightness pulsed proton source which could produce a weakly convergent approx. 10 kA proton beam in a field free drift region. This was accomplished at approx. 250 keV, and preliminary beam propagation experiments were performed. It was concluded that a proper simulation experiment would require a higher voltage beam. An upgraded version of the existing generator, which would have produced a 30 kA beam at about 500 keV, and further propagation experiments were proposed as part of our unsuccessful renewal proposal dated October 15, 1979

  12. Laboratory-based micro-X-ray fluorescence setup using a von Hamos crystal spectrometer and a focused beam X-ray tube

    International Nuclear Information System (INIS)

    Kayser, Y.; Błachucki, W.; Dousse, J.-Cl.; Hoszowska, J.; Neff, M.; Romano, V.

    2014-01-01

    The high-resolution von Hamos bent crystal spectrometer of the University of Fribourg was upgraded with a focused X-ray beam source with the aim of performing micro-sized X-ray fluorescence (XRF) measurements in the laboratory. The focused X-ray beam source integrates a collimating optics mounted on a low-power micro-spot X-ray tube and a focusing polycapillary half-lens placed in front of the sample. The performances of the setup were probed in terms of spatial and energy resolution. In particular, the fluorescence intensity and energy resolution of the von Hamos spectrometer equipped with the novel micro-focused X-ray source and a standard high-power water-cooled X-ray tube were compared. The XRF analysis capability of the new setup was assessed by measuring the dopant distribution within the core of Er-doped SiO 2 optical fibers

  13. Laboratory-based micro-X-ray fluorescence setup using a von Hamos crystal spectrometer and a focused beam X-ray tube.

    Science.gov (United States)

    Kayser, Y; Błachucki, W; Dousse, J-Cl; Hoszowska, J; Neff, M; Romano, V

    2014-04-01

    The high-resolution von Hamos bent crystal spectrometer of the University of Fribourg was upgraded with a focused X-ray beam source with the aim of performing micro-sized X-ray fluorescence (XRF) measurements in the laboratory. The focused X-ray beam source integrates a collimating optics mounted on a low-power micro-spot X-ray tube and a focusing polycapillary half-lens placed in front of the sample. The performances of the setup were probed in terms of spatial and energy resolution. In particular, the fluorescence intensity and energy resolution of the von Hamos spectrometer equipped with the novel micro-focused X-ray source and a standard high-power water-cooled X-ray tube were compared. The XRF analysis capability of the new setup was assessed by measuring the dopant distribution within the core of Er-doped SiO2 optical fibers.

  14. Dopant profiling of focused ion beam milled semiconductors using off-axis electron holography; reducing artifacts, extending detection limits and reducing the effects of gallium implantation

    DEFF Research Database (Denmark)

    Cooper, David; Ailliot, Cyril; Barnes, Jean-Paul

    2010-01-01

    Focused ion beam (FIB) milling is one of the few specimen preparation techniques that can be used to prepare parallel-sided specimens with nm-scale site specificity for examination using off-axis electron holography in the transmission electron microscope (TEM). However, FIB milling results...... thickness is dependent on both the operating voltage and type of ion used during FIB milling....

  15. A New Approach to Studying Biological and Soft Materials Using Focused Ion Beam Scanning Electron Microscopy (FIB SEM)

    International Nuclear Information System (INIS)

    Stokes, D J; Morrissey, F; Lich, B H

    2006-01-01

    Over the last decade techniques such as confocal light microscopy, in combination with fluorescent labelling, have helped biologists and life scientists to study biological architectures at tissue and cell level in great detail. Meanwhile, obtaining information at very small length scales is possible with the combination of sample preparation techniques and transmission electron microscopy (TEM) or scanning transmission electron microscopy (STEM). Scanning electron microscopy (SEM) is well known for the determination of surface characteristics and morphology. However, the desire to understand the three dimensional relationships of meso-scale hierarchies has led to the development of advanced microscopy techniques, to give a further complementary approach. A focused ion beam (FIB) can be used as a nano-scalpel and hence allows us to reveal internal microstructure in a site-specific manner. Whilst FIB instruments have been used to study and verify the three-dimensional architecture of man made materials, SEM and FIB technologies have now been brought together in a single instrument representing a powerful combination for the study of biological specimens and soft materials. We demonstrate the use of FIB SEM to study three-dimensional relationships for a range of length scales and materials, from small-scale cellular structures to the larger scale interactions between biomedical materials and tissues. FIB cutting of heterogeneous mixtures of hard and soft materials, resulting in a uniform cross-section, has proved to be of particular value since classical preparation methods tend to introduce artefacts. Furthermore, by appropriate selection, we can sequentially cross-section to create a series of 'slices' at specific intervals. 3D reconstruction software can then be used to volume-render information from the 2D slices, enabling us to immediately see the spatial relationships between microstructural components

  16. Statistically-averaged rate equations for intense nonneutral beam propagation through a periodic solenoidal focusing field based on the nonlinear Vlasov-Maxwell equations

    Energy Technology Data Exchange (ETDEWEB)

    Davidson, R.C.; Lee, W.W.; Stoltz, P.

    1997-08-01

    This paper presents a detailed formulation and analysis of the rate equations for statistically-averaged quantities for an intense nonneutral beam propagating through a periodic solenoidal focusing field B{sup sol}(x). The analysis is based on the nonlinear Vlasov-Maxwell equations in the electrostatic approximation, assuming a thin beam with characteristic beam radius r{sub b} {much_lt} S. The results are applied to investigate the nonlinear evolution of the generalized entropy, mean canonical angular momentum {l_angle}P{sub {theta}}{r_angle}, center-of-mass motion for {l_angle}X{r_angle} and {l_angle}Y{r_angle}, mean kinetic energy (1/2) {l_angle}X{sup {prime}2} + Y{sup {prime}2}{r_angle}, mean-square beam radius {l_angle}X{sup 2} + Y{sup 2}{r_angle}, and coupled rate equations for the unnormalized transverse emittance {epsilon}(s) and root-mean-square beam radius R{sub b}(s) = {l_angle}X{sup 2} + Y{sup 2}{r_angle}{sup 1/2}. Global energy balance is discussed, and the coupled rate equations for {epsilon}(s) and R{sub b}(s) are examined for the class of axisymmetric beam distributions F{sub b}.

  17. Focusing peculiarities of ion-channel guiding on a relativistic electron beam in a free-electron laser with a three-dimensional wiggler

    International Nuclear Information System (INIS)

    Ouyang, Zhengbiao; Zhang, Shi-Chang

    2014-01-01

    In a free-electron laser the ‘natural focusing’ effect of a three-dimensional wiggler is too weak to confine the transport of a relativistic electron beam when the beam has a high current and consequently an external focusing system is often needed. In this paper we study the focusing peculiarities of an ion-channel guide field on an electron beam. Nonlinear simulations of an electron beam transport show that, compared to an axial guide magnetic field, the ion-channel guide field results in smaller velocity–space and configuration–space spreads. The intrinsic mechanism of this physical phenomenon is that the ion-channel guide field confines the trajectory of the electron motion resulting in a smaller instantaneous curvature radius and a slighter curvature-center excursion than an axial guide magnetic field does. It is also found that, unlike with an axial guide magnetic field, over-focusing may occur if the ion-channel guide field is too strong. (paper)

  18. A quantitative evaluation of the L.B.W. efficiency on AISI 304 bead on plates welded under different focusing and tilted laser beam conditions

    Science.gov (United States)

    Daurelio, Giuseppe; Ludovico, Antonio D.; Lugara, M. P.; De Filippis, L. A. C.; Spera, A. M.; Rocco, S.

    2005-03-01

    The aim of this search is to evaluate the WE (Welding Efficiency) of each beads versus the different positions of the laser beam optical focus (positive or negative or zero values) respect to the work-piece surface and also versus different laser beam incidence angles (80° and 70°) by using two laser power levels (2 and 2.5 KW) and two welding speeds (3 and 6 m/min). The WE values have been reported on two DA.LU. method plots and the relate evaluations regarding the same ones as well as the recorded best parameters have been evidenced.

  19. Superresolution beams

    CSIR Research Space (South Africa)

    Ngcobo, S

    2011-11-01

    Full Text Available zones capable of introducing a phase shift of zero or p on the alternately out of phase rings of the TEMp0 beams into a unified phase and then focusing the rectified beam to generate a high resolution beam which has a Gaussian beam intensity distribution...

  20. 3D imaging of cells and tissues by focused ion beam/scanning electron microscopy (FIB/SEM).

    Science.gov (United States)

    Drobne, Damjana

    2013-01-01

    Integration of a scanning electron microscope (SEM) and focused ion beam (FIB) technology into a single FIB/SEM system permits use of the FIB as a nano-scalpel to reveal site-specific subsurface microstructures which can be examined in great detail by SEM. The FIB/SEM technology is widely used in the semiconductor industry and material sciences, and recently its use in the life sciences has been initiated. Samples for FIB/SEM investigation can be either embedded in a plastic matrix, the traditional means of preparation of transmission electron microscopy (TEM) specimens, or simply dried as in samples prepared for SEM imaging. Currently, FIB/SEM is used in the life sciences for (a) preparation by the lift-out technique of lamella for TEM analysis, (b) tomography of samples embedded in a matrix, and (c) in situ site-specific FIB milling and SEM imaging using a wide range of magnifications. Site-specific milling and imaging has attracted wide interest as a technique in structural research of single eukaryotic and prokaryotic cells, small animals, and different animal tissue, but it still remains to be explored more thoroughly. In the past, preparation of samples for site-specific milling and imaging by FIB/SEM has typically adopted the embedding techniques used for TEM samples, and which have been very well described in the literature. Sample preparation protocols for the use of dried samples in FIB/SEM have been less well investigated. The aim of this chapter is to encourage application of FIB/SEM on dried biological samples. A detailed description of conventional dried sample preparation and FIB/SEM investigation of dried biological samples is presented. The important steps are described and illustrated, and direct comparison between embedded and dried samples of same tissues is provided. The ability to discover links between gross morphology of the tissue or organ, surface characteristics of any selected region, and intracellular structural details on the nanometer

  1. Design studies of an electrostatic quadrupole channel for transport of a high-brightness H- beam and comparison with gas focusing

    International Nuclear Information System (INIS)

    Chang, C.R.; Horowitz, E.; Reiser, M.

    1989-01-01

    Transport of low-energy, high-brightness H - beams from the ion source to the radio-frequency quadrupole (RFQ) accelerator requires the solution of several physics and engineering problems to avoid particle losses and emittance growth. The authors developed a conceptual design of an electrostatic quadrupole channel for transport of a 120 keV, 120 mA, H - beam into a 425 MHz RFQ with low emittance growth and high transmission efficiency. This design satisfies several constraints imposed by voltage breakdown and beam optics considerations. The system will consist entirely of electrostatic lenses which prevent plasma build-up and eliminate possible emittance growth from plasma fluctuations. Pertinent design features a worst case non-linear analysis for the electrostatic quadrupole channel, and first results of a particle simulation code used to study beam loss and emittance growth are reported. As an alternative to the electrostatic quadrupole concept, gas focusing is being investigated for transporting low-energy H - beams. Recent results from the numerical simulations of such a gas focussing channel are presented

  2. The Dynamics of Fine Mode Aerosol Optical Properties in South Korea from AERONET and Aircraft Observations with a Focus on Cases with Large Cloud Fraction and/or Fog During KORUS-AQ

    Science.gov (United States)

    Eck, T. F.; Holben, B. N.; Kim, J.; Choi, M.; Giles, D. M.; Schafer, J.; Smirnov, A.; Slutsker, I.; Sinyuk, A.; Sorokin, M. G.; Kraft, J.; Beyersdorf, A. J.; Anderson, B. E.; Thornhill, K. L., II; Crawford, J. H.

    2017-12-01

    The focus of our investigation is of major fine mode aerosol pollution events in South Korea, particularly when cloud fraction is high. This work includes the analysis of AERONET data utilizing the Spectral Deconvolution Algorithm to enable detection of fine mode aerosol optical depth (AOD) near to clouds. Additionally we analyze the newly developed AERONET V3 data sets that have significant changes to cloud screening algorithms. Comparisons of aerosol optical depth are made between AERONET Versions 2 and 3 for both long-term climatology data and for specific 2016 cases, especially in May and June 2016 during the KORUS-AQ field campaign. In general the Version 3 cloud screening allows many more fine mode AOD observations to reach Level 2 when cloud amount is high, as compared to Version 2, thereby enabling more thorough analysis of these types of cases. Particular case studies include May 25-26, 2016 when cloud fraction was very high over much of the peninsula, associated with a frontal passage and advection of pollution from China. Another interesting case is June 9, 2016 when there was fog over the West Sea, and this seems to have affected aerosol properties well downwind over the Korean peninsula. Both of these days had KORUS-AQ research aircraft flights that provided observations of aerosol absorption, particle size distributions and vertical profiles of extinction. AERONET retrievals and aircraft in situ measurements both showed high single scattering albedo (weak absorption) on these cloudy days. We also investigate the relationship between aerosol fine mode radius and AOD and the relationship between aerosol single scattering albedo and fine mode particle radius from the AERONET almucantar retrievals for the interval of April through June 2016 for 17 AERONET sites in South Korea. Strongly increasing fine mode radius (leading to greater scattering efficiency) as fine mode AOD increased is one factor contributing to a trend of increasing single scattering

  3. Enhanced Etching, Surface Damage Recovery, and Submicron Patterning of Hybrid Perovskites using a Chemically Gas-Assisted Focused-Ion Beam for Subwavelength Grating Photonic Applications

    KAUST Repository

    Alias, Mohd Sharizal

    2015-12-22

    The high optical gain and absorption of organic–inorganic hybrid perovskites have attracted attention for photonic device applications. However, owing to the sensitivity of organic moieties to solvents and temperature, device processing is challenging, particularly for patterning. Here, we report the direct patterning of perovskites using chemically gas-assisted focused-ion beam (GAFIB) etching with XeF2 and I2 precursors. We demonstrate etching enhancement in addition to controllability and marginal surface damage compared to focused-ion beam (FIB) etching without precursors. Utilizing the GAFIB etching, we fabricated a uniform and periodic submicron perovskite subwavelength grating (SWG) absorber with broadband absorption and nanoscale precision. Our results demonstrate the use of FIB as a submicron patterning tool and a means of providing surface treatment (after FIB patterning to minimize optical loss) for perovskite photonic nanostructures. The SWG absorber can be patterned on perovskite solar cells to enhance the device efficiency through increasing light trapping and absorption.

  4. First observation of meridional focusing of an x-ray beam using diffraction by a crystal with a transverse groove

    Czech Academy of Sciences Publication Activity Database

    Hrdý, Jaromír; Franc, František; Artemiev, Nikolai; Hrdá, Jaromíra; Ziegler, E.; Bigault, Th.; Freud, A. K.

    2001-01-01

    Roč. 8, - (2001), s. 1203-1206 ISSN 0909-0495 R&D Projects: GA AV ČR IAA1010104; GA MPO PZ-CH/22 Institutional research plan: CEZ:AV0Z1010914 Keywords : x-ray beam Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.519, year: 2001

  5. Single grain boundary break junction for suspended nanogap electrodes with gapwidth down to 1-2 nm by focused ion beam milling.

    Science.gov (United States)

    Cui, Ajuan; Liu, Zhe; Dong, Huanli; Wang, Yujin; Zhen, Yonggang; Li, Wuxia; Li, Junjie; Gu, Changzhi; Hu, Wenping

    2015-05-20

    Single grain boundary junctions are used for the fabrication of suspended nanogap electrodes with a gapwidth down to 1-2 nm through the break of such junctions by focused ion beam (FIB) milling. With advantages of stability and no debris, such nanogap electrodes are suitable for single molecular electronic device construction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Application of the relativistic electron beams originating in the discharges of plasma focus type for the combined laser-REB plasma heating

    International Nuclear Information System (INIS)

    Gribkov, V.A.

    1976-01-01

    Experimental investigations of the recent years allow to treat the discharge of plasma-focus-type (DPF) as an inductive storage with the switching time of the order of tens nsec. It results from the interferometry and X-ray measurements. The moment of the current sheath rupture coincides with the beginning of hard X-ray pulse. A considerable part of the bank energy (concentrated in the magnetic field near focus) converts into the electron beam energy with the mean energy of electrons of the order of 100 keV after the disruption of the current. The interferometry is allowed to investigate the dynamics of REB in DPF. The beam appeared to be divided into several filaments, and disturbed by ''hose'' instability and self-focusing inside the residual plasma. The X-ray pinhole pictures showed high plasma luminosity in the regions of beam focus, a neutron yield of the set-up had its maximum at this moment. All these data with anomalous scattering of diagnostic laser light in this region, high level of plasma noise with the frequency of the order of Langmuir frequency (by the factor of 10 6 ) and broad neutron spectra show us that an effective turbulent interaction of REB with plasma takes place in DPF. An experiment of particular interest for us involves the realization of laser initiated breakdown in the insulator and a combined laser-REB plasma heating. Analytical calculations indicate that when the REB energy is of the order of 10 4 to 10 6 J and the laser pulse duration of 10 -9 to 10 -10 sec, the laser energy of the order of 10 3 J is required for the experiment

  7. Pulsed laser-assisted focused electron-beam-induced etching of titanium with XeF2: enhanced reaction rate and precursor transport.

    Science.gov (United States)

    Noh, J H; Fowlkes, J D; Timilsina, R; Stanford, M G; Lewis, B B; Rack, P D

    2015-02-25

    In order to enhance the etch rate of electron-beam-induced etching, we introduce a laser-assisted focused electron-beam-induced etching (LA-FEBIE) process which is a versatile, direct write nanofabrication method that allows nanoscale patterning and editing. The results demonstrate that the titanium electron stimulated etch rate via the XeF2 precursor can be enhanced up to a factor of 6 times with an intermittent pulsed laser assist. The evolution of the etching process is correlated to in situ stage current measurements and scanning electron micrographs as a function of time. The increased etch rate is attributed to photothermally enhanced Ti-F reaction and TiF4 desorption and in some regimes enhanced XeF2 surface diffusion to the reaction zone.

  8. Low-dose patterning of platinum nanoclusters on carbon nanotubes by focused-electron-beam-induced deposition as studied by TEM

    Directory of Open Access Journals (Sweden)

    Xiaoxing Ke

    2013-02-01

    Full Text Available Focused-electron-beam-induced deposition (FEBID is used as a direct-write approach to decorate ultrasmall Pt nanoclusters on carbon nanotubes at selected sites in a straightforward maskless manner. The as-deposited nanostructures are studied by transmission electron microscopy (TEM in 2D and 3D, demonstrating that the Pt nanoclusters are well-dispersed, covering the selected areas of the CNT surface completely. The ability of FEBID to graft nanoclusters on multiple sides, through an electron-transparent target within one step, is unique as a physical deposition method. Using high-resolution TEM we have shown that the CNT structure can be well preserved thanks to the low dose used in FEBID. By tuning the electron-beam parameters, the density and distribution of the nanoclusters can be controlled. The purity of as-deposited nanoclusters can be improved by low-energy electron irradiation at room temperature.

  9. Low-dose patterning of platinum nanoclusters on carbon nanotubes by focused-electron-beam-induced deposition as studied by TEM

    Science.gov (United States)

    Bittencourt, Carla; Bals, Sara; Van Tendeloo, Gustaaf

    2013-01-01

    Summary Focused-electron-beam-induced deposition (FEBID) is used as a direct-write approach to decorate ultrasmall Pt nanoclusters on carbon nanotubes at selected sites in a straightforward maskless manner. The as-deposited nanostructures are studied by transmission electron microscopy (TEM) in 2D and 3D, demonstrating that the Pt nanoclusters are well-dispersed, covering the selected areas of the CNT surface completely. The ability of FEBID to graft nanoclusters on multiple sides, through an electron-transparent target within one step, is unique as a physical deposition method. Using high-resolution TEM we have shown that the CNT structure can be well preserved thanks to the low dose used in FEBID. By tuning the electron-beam parameters, the density and distribution of the nanoclusters can be controlled. The purity of as-deposited nanoclusters can be improved by low-energy electron irradiation at room temperature. PMID:23399584

  10. Studies for the development of a micro-focus monochromatic x-ray source with making use of a highly charged heavy ion beam

    International Nuclear Information System (INIS)

    Nakamura, Nobuyuki; Yoshiyasu, Nobuo; Nakayama, Ryo; Watanabe, Hirofumi

    2008-01-01

    We propose a new scheme for a micro-focus monochromatic X-ray source using a focused highly charged ion beam colliding with a solid surface. When highly charged ion approaches a surface, many electrons are captured into the ion and the so-called hollow atom is produced. The hollow atom will decay by emitting X-rays before and after hitting the surface. Such X-rays do not contain any contribution from bremsstrahlung, so that monochromatic X-rays can be obtained by using proper filters. For the first step of realizing the proposed scheme, an ion focusing system with a glass capillary has been developed. In order to study the monochromaticity of the emission, X-ray spectra from hollow atoms produced in the collisions between highly charged heavy ions and several surfaces have been observed. (author)

  11. Molecular beams

    International Nuclear Information System (INIS)

    Ramsey, N.F.

    1985-01-01

    This book is a timeless and rather complete theoretical and experimental treatment of electric and magnetic resonance molecular-beam experiments for studying the radio frequency spectra of atoms and molecules. The theory of interactions of the nucleus with atomic and molecular fields is extensively presented. Measurements of atomic and nuclear magnetic moments, electric multipole moments, and atomic fine and hyperfine structure are detailed. Useful but somewhat outdated chapters on gas kinetics, molecular beam design, and experimental techniques are also included

  12. Application of ion beams in materials science of radioactive waste forms: focus on the performance of spent nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    Garrido, Frederico [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, CNRS-IN2P3-Universite Paris-Sud, Batiments 104-108, 91405 Orsay Campus (France)]. E-mail: garrido@csnsm.in2p3.fr; Nowicki, Lech [Andrzej Soltan Institute for Nuclear Studies, Hoza 69, 00-681 Warsaw (Poland); Thome, Lionel [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, CNRS-IN2P3-Universite Paris-Sud, Ba-hat timents 104-108, 91405 Orsay Campus (France)

    2005-10-15

    Ion beam techniques provide unique tools for the qualification of radioactive waste forms. They address three major issues: (i) the simulation by ion irradiation of the stability of a matrix submitted to radiative environment; (ii) the doping of a material with stable or radioactive elements which simulate the species to be confined; (iii) the characterisation of a material via nuclear microanalysis techniques. Among various classes of nuclear matrices the spent nuclear fuel is widely considered as a potential candidate for the stabilisation of radioactive wastes in scenarios of long term interim storage or final geological disposal. Illustrative examples revealing the potentialities of the use of ion beams either as a pure characterisation tool - to investigate the chemical stability of the UO{sub 2} matrix under an oxygen potential - or in a combined way (e.g. irradiation/characterisation, doping/characterisation) - to explore the radiation stability and the behaviour of foreign species - are presented. Transformations (stoichiometry, depth and structure of growing hyperstoichiometric U{sub 4}O{sub 9}/U{sub 3}O{sub 7} oxides) occurring during low-temperature air oxidation of uranium dioxide single crystals are reported. Swift heavy ion irradiation of UO{sub 2} single crystals leads to a peculiar single crystal-polycrystal transformation (i.e. polygonisation of the fluorite-type structure of the material). Irradiation of UO{sub 2} at low energy shows that the damage production is directly linked to the energy deposited in nuclear elastic collisions. The lattice location of helium atoms (generated in large amount during the storage period) in interstitial octahedral positions is discussed.

  13. Near-field beam focusing by a single bare subwavelength metal slit with the high-index transmission space.

    Science.gov (United States)

    Guo, Yan; Zhao, Bo; Yang, Jianjun

    2013-06-17

    We theoretically demonstrate that a single bare subwavelength metal slit without any surrounding corrugations can have a capability to steer the incident light into focusing patterns by introducing a high index in the transmission half-space. The focusing properties are identified to depend on both the slit width and the output permittivity. The underlying physics lies in the interference of quasi-cylindrical waves scattered from the slit, and our proposed model agrees well with the simulation results. This finding is believed to inspire some novel ideas for the nano-optics design.

  14. Studying signal collection in the punch-through protection area of a silicon micro-strip sensor using a micro-focused X-ray beam

    CERN Document Server

    Poley, Anne-luise; The ATLAS collaboration

    2018-01-01

    For the Phase-II Upgrade of the ATLAS detector, a new, all-silicon tracker will be constructed in order to cope with the increased track density and radiation level of the High-Luminosity Large Hadron Collider. While silicon strip sensors are designed to minimise the fraction of dead material and maximise the active area of a sensor, concessions must be made to the requirements of operating a sensor in a particle physics detector. Sensor geometry features like the punch-through protection deviate from the standard sensor architecture and thereby affect the charge collection in that area. In order to study the signal collection of silicon strip sensors over their punch-through-protection area, ATLAS silicon strip sensors were scanned with a micro-focused X-ray beam at the Diamond Light Source. Due to the highly focused X-ray beam ($\\unit[2\\times3]{\\upmu\\text{m}}^2$) and the short average path length of an electron after interaction with an X-ray photon ($\\unit[\\leq2]{\\upmu\\text{m}}$), local signal collection i...

  15. A new high-resolution small-angle X-ray scattering apparatus using a fine-focus rotating anode, point-focusing collimation and a position-sensitive proportional counter

    International Nuclear Information System (INIS)

    Yoda, O.

    1984-01-01

    A high-resolution small-angle X-ray scattering camera has been built, which has the following features. (i) The point collimation optics employed allows the scattering cross section of the sample to be directly measured without corrections for desmearing. (ii) A small-angle resolution better than 0.5 mrad is achieved with a camera length of 1.6 m. (iii) A high photon flux of 0.9 photons μs -1 is obtained on the sample with the rotating-anode X-ray generator operated at 40 kV-30 mA. (iv) Incident X-rays are monochromatized by a bent quartz crystal, which makes the determination of the incident X-ray intensity simple and unambiguous. (v) By rotation of the position-sensitive proportional counter around the direct beam, anisotropic scattering patterns can be observed without adjusting the sample. Details of the design and performance are presented with some applications. (Auth.)

  16. Shadow effects in simulated ultrasound images derived from computed tomography images using a focused beam tracing model

    DEFF Research Database (Denmark)

    Pham, An Hoai; Lundgren, Bo; Stage, Bjarne

    2012-01-01

    Simulation of ultrasound images based on computed tomography (CT) data has previously been performed with different approaches. Shadow effects are normally pronounced in ultrasound images, so they should be included in the simulation. In this study, a method to capture the shadow effects has been......Focus ultrasound scanner (BK Medical, Herlev, Denmark) equipped with a dedicated research interface giving access to beamformed radio frequency data. CT images were obtained with an Aquilion ONE Toshiba CT scanner (Toshiba Medical Systems Corp., Tochigi, Japan). CT data were mapped from Hounsfield units...

  17. Aespoe Hard Rock Laboratory. The use of focused ion beams for structural characterisation of bentonite. A feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Wegden, Marie; Kristiansson, Per (Division of Nuclear Physics, Lund Inst. of Technology (Sweden)); Svensson, Daniel; Sjoeland, Anders (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden))

    2009-07-01

    Bentonite clay is planned to be used in the KBS-3 concept for future nuclear high level waste (HLW) repository in Sweden. In the concept the spent nuclear fuel is placed in an iron insert, which is encapsulated in a copper canister. The copper canister is embedded in compacted bentonite and deposited at 500 m depth in granite bedrock. The compacted bentonite will act as a buffer material, giving mechanical support for the copper canister, reducing water movements and capturing potentially escaping radionuclides. Bentonite contains high amounts of smectite minerals (most common is montmorillonite), which are swelling clay minerals. The smectite minerals are layered and have the ability to store water in its structure. This is done by intercalating water between the layers and expanding the interlayer distance. The exceptional swelling capacity makes bentonite a suitable buffer material that works as a sealant and barrier. Heterogeneity in the material, compaction and in swelling may result in porosity, both on the nano- and micrometre scale. This may affect the permeability of the clay and may mediate the transport of radionuclides, cations and corrosion products. The aim of this work is to investigate the feasibility of using common ion beam techniques for structural characterisation of bentonite, including studying the mineral composition and the coarse porosity. The analytical techniques used were scanning transmission ion microscopy (STIM), particle-induced X-ray emission (PIXE) and elastic p-p scattering, performed at the Lund Nuclear Microprobe. On-axis STIM analysis was performed in order to measure and map the areal mass density of the sample. Since it was impossible to differentiate an increase in thickness from an area of higher mass density, as well as discerning depth variations, the STIM analysis was also performed in tomographic mode, in an attempt to obtain 3D structural information. The tomographic reconstruction showed that the bentonite had an

  18. Intercostal high intensity focused ultrasound for liver ablation: The influence of beam shaping on sonication efficacy and near-field risks

    International Nuclear Information System (INIS)

    Greef, M. de; Wijlemans, J. W.; Bartels, L. W.; Moonen, C. T. W.; Ries, M.; Schubert, G.; Koskela, J.

    2015-01-01

    Purpose: One of the major issues in high intensity focused ultrasound ablation of abdominal lesions is obstruction of the ultrasound beam by the thoracic cage. Beam shaping strategies have been shown by several authors to increase focal point intensity while limiting rib exposure. However, as rib obstruction leaves only part of the aperture available for energy transmission, conserving total emitted acoustic power, the intensity in the near-field tissues inherently increases after beam shaping. Despite of effective rib sparing, those tissues are therefore subjected to increased risk of thermal damage. In this study, for a number of clinically representative intercostal sonication geometries, modeling clinically available hardware, the effect of beam shaping on both the exposure of the ribs and near-field to acoustic energy was evaluated and the implications for the volumetric ablation rate were addressed. Methods: A relationship between rib temperature rise and acoustic energy density was established by means of in vivo MR thermometry and simulations of the incident acoustic energy for the corresponding anatomies. This relationship was used for interpretation of rib exposure in subsequent numerical simulations in which rib spacing, focal point placement, and the focal point trajectory were varied. The time required to heat a targeted region to 65 °C was determined without and with the application of beam shaping. The required sonication time was used to calculate the acoustic energy density at the fat–muscle interface and at the surface of the ribs. At the fat–muscle interface, exposure was compared to available literature data and rib exposure was interpreted based on the earlier obtained relation between measured temperature rise and simulated acoustic energy density. To estimate the volumetric ablation rate, the cool-down time between periods of energy exposure was estimated using a time-averaged power limit of 100 kJ/h. Results: At the level of the ribs

  19. Intercostal high intensity focused ultrasound for liver ablation: The influence of beam shaping on sonication efficacy and near-field risks

    Energy Technology Data Exchange (ETDEWEB)

    Greef, M. de, E-mail: m.degreef@umcutrecht.nl; Wijlemans, J. W.; Bartels, L. W.; Moonen, C. T. W.; Ries, M. [Imaging Division, University Medical Center Utrecht, Utrecht 3508GA (Netherlands); Schubert, G.; Koskela, J. [Philips Healthcare, Vantaa FI-01511 (Finland)

    2015-08-15

    Purpose: One of the major issues in high intensity focused ultrasound ablation of abdominal lesions is obstruction of the ultrasound beam by the thoracic cage. Beam shaping strategies have been shown by several authors to increase focal point intensity while limiting rib exposure. However, as rib obstruction leaves only part of the aperture available for energy transmission, conserving total emitted acoustic power, the intensity in the near-field tissues inherently increases after beam shaping. Despite of effective rib sparing, those tissues are therefore subjected to increased risk of thermal damage. In this study, for a number of clinically representative intercostal sonication geometries, modeling clinically available hardware, the effect of beam shaping on both the exposure of the ribs and near-field to acoustic energy was evaluated and the implications for the volumetric ablation rate were addressed. Methods: A relationship between rib temperature rise and acoustic energy density was established by means of in vivo MR thermometry and simulations of the incident acoustic energy for the corresponding anatomies. This relationship was used for interpretation of rib exposure in subsequent numerical simulations in which rib spacing, focal point placement, and the focal point trajectory were varied. The time required to heat a targeted region to 65 °C was determined without and with the application of beam shaping. The required sonication time was used to calculate the acoustic energy density at the fat–muscle interface and at the surface of the ribs. At the fat–muscle interface, exposure was compared to available literature data and rib exposure was interpreted based on the earlier obtained relation between measured temperature rise and simulated acoustic energy density. To estimate the volumetric ablation rate, the cool-down time between periods of energy exposure was estimated using a time-averaged power limit of 100 kJ/h. Results: At the level of the ribs

  20. Anne Fine

    Directory of Open Access Journals (Sweden)

    Philip Gaydon

    2015-04-01

    Full Text Available An interview with Anne Fine with an introduction and aside on the role of children’s literature in our lives and development, and our adult perceptions of the suitability of childhood reading material. Since graduating from Warwick in 1968 with a BA in Politics and History, Anne Fine has written over fifty books for children and eight for adults, won the Carnegie Medal twice (for Goggle-Eyes in 1989 and Flour Babies in 1992, been a highly commended runner-up three times (for Bill’s New Frock in 1989, The Tulip Touch in 1996, and Up on Cloud Nine in 2002, been shortlisted for the Hans Christian Andersen Award (the highest recognition available to a writer or illustrator of children’s books, 1998, undertaken the positon of Children’s Laureate (2001-2003, and been awarded an OBE for her services to literature (2003. Warwick presented Fine with an Honorary Doctorate in 2005. Philip Gaydon’s interview with Anne Fine was recorded as part of the ‘Voices of the University’ oral history project, co-ordinated by Warwick’s Institute of Advanced Study.

  1. Ion irradiation effects on a magnetic Si/Ni/Si trilayer and lateral magnetic-nonmagnetic multistrip patterning by focused ion beam

    Science.gov (United States)

    Dev, B. N.; Banu, Nasrin; Fassbender, J.; Grenzer, J.; Schell, N.; Bischoff, L.; Groetzschel, R.; McCord, J.

    2017-10-01

    Fabrication of a multistrip magnetic/nonmagnetic structure in a thin sandwiched Ni layer [Si(5 nm)/Ni(15 nm)/Si] by a focused ion beam (FIB) irradiation has been attempted. A control experiment was initially performed by irradiation with a standard 30 keV Ga ion beam at various fluences. Analyses were carried out by Rutherford backscattering spectrometry, X-ray reflectivity, magnetooptical Kerr effect (MOKE) measurements and MOKE microscopy. With increasing ion fluence, the coercivity as well as Kerr rotation decreases. A threshold ion fluence has been identified, where ferromagnetism of the Ni layer is lost at room temperature and due to Si incorporation into the Ni layer, a Ni0.68Si0.32 alloy layer is formed. This fluence was used in FIB irradiation of parallel 50 nm wide stripes, leaving 1 µm wide unirradiated stripes in between. MOKE microscopy on this FIB-patterned sample has revealed interacting magnetic domains across several stripes. Considering shape anisotropy effects, which would favour an alignment of magnetization parallel to the stripe axis, the opposite behaviour is observed. Magneto-elastic effects introducing a stress-induced anisotropy component oriented perpendicular to the stripe axis are the most plausible explanation for the observed behaviour.

  2. A method to improve the quality of 2.5 dimensional micro-and nano-structures produced by focused ion beam machining.

    Science.gov (United States)

    De Felicis, Daniele; Mughal, Muhammad Zeeshan; Bemporad, Edoardo

    2017-10-01

    The present work deals with a new technique to produce complex micro- and nano-scale patterns with high accuracy by FIB micro machining. The proposed method is related to the production of stream file, which is optimized through a software interface. A unique sampling approach is used to optimize the conversion from a 3D meshed CAD object to the focused ion beam (FIB) digital to analogue converter (DAC). The method uses a novel scan strategy, sensitive to the pattern local geometry and size, to define the optimal ion beam path, dwell time and the scanning pitch. This not only allows to minimize the redeposition but also to obtain accurate and scalable milling routines. In order to show the applicability of the method, a hemisphere and a pyramid shape are milled and compared to the shapes obtained using the conventional techniques. Results show that the method is very effective in producing complex shapes while overcoming the detrimental effect of conventional raster/serpentine FIB strategies, such as redeposition. Lastly, a fish-net structure with a pitch of ∼200nm as well as a series of truncated cones with sub-micrometrical details are realized to show the potential impact of this new method. Results show that a spatial resolution of less than 100nm is achievable with the help of this method. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Focused ion beam scan routine, dwell time and dose optimizations for submicrometre period planar photonic crystal components and stamps in silicon

    International Nuclear Information System (INIS)

    Hopman, Wico C L; Ay, Feridun; Hu, Wenbin; Gadgil, Vishwas J; Kuipers, Laurens; Pollnau, Markus; Ridder, Rene M de

    2007-01-01

    Focused ion beam (FIB) milling is receiving increasing attention for nanostructuring in silicon (Si). These structures can for example be used for photonic crystal structures in a silicon-on-insulator (SOI) configuration or for moulds which can have various applications in combination with imprint technologies. However, FIB fabrication of submicrometre holes having perfectly vertical sidewalls is still challenging due to the redeposition effect in Si. In this study we show how the scan routine of the ion beam can be used as a sidewall optimization parameter. The experiments have been performed in Si and SOI. Furthermore, we show that sidewall angles as small as 1.5 0 are possible in Si membranes using a spiral scan method. We investigate the effect of the dose, loop number and dwell time on the sidewall angle, interhole milling and total milling depth by studying the milling of single and multiple holes into a crystal. We show that the sidewall angles can be as small as 5 0 in (bulk) Si and SOI when applying a larger dose. Finally, we found that a relatively large dwell time of 1 ms and a small loop number is favourable for obtaining vertical sidewalls. By comparing the results with those obtained by others, we conclude that the number of loops at a fixed dose per hole is the parameter that determines the sidewall angle and not the dwell time by itself

  4. In-situ integrity control of frozen-hydrated, vitreous lamellas prepared by the cryo-focused ion beam-scanning electron microscope.

    Science.gov (United States)

    de Winter, D A Matthijs; Mesman, Rob J; Hayles, Michael F; Schneijdenberg, Chris T W M; Mathisen, Cliff; Post, Jan A

    2013-07-01

    Recently a number of new approaches have been presented with the intention to produce electron beam transparent cryo-sections (lamellas in FIB-SEM terminology) from hydrated vitreously frozen cryo samples with a Focused Ion Beam (FIB) system, suitable for cryo-Transmission Electron Microscopy (cryo-TEM). As the workflow is still challenging and time consuming, it is important to be able to determine the integrity and suitability (cells vs. no cells; vitreous vs. crystalline) of the lamellas. Here we present an in situ method that tests both conditions by using the cryo-Scanning Electron Microscope (cryo-SEM) in transmission mode (TSEM; Transmission Scanning Electron Microscope) once the FIB-made lamella is ready. Cryo-TSEM imaging of unstained cells yields strong contrast, enabling direct imaging of material present in the lamellas. In addition, orientation contrast is shown to be suitable for distinguishing crystalline lamellas from vitreous lamellas. Tilting the stage a few degrees results in changes of contrast between ice grains as a function of the tilt angle, whereas the contrast of areas with vitreous ice remains unchanged as a function of the tilt angle. This orientation contrast has subsequently been validated by cryo-Electron BackScattered Diffraction (EBSD) in transmission mode. Integration of the presented method is discussed and the role it can play in future developments for a new and innovative all-in-one cryo-FIB-SEM life sciences instrument. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. Effects of focused ion beam milling on the compressive behavior of directionally solidified micro-pillars and the nanoindentation response of an electro-polished surface

    International Nuclear Information System (INIS)

    Shim, Sang Hoon; Bei, Hongbin; Miller, Michael K; Pharr, George Mathews; George, Easo P

    2009-01-01

    Focused ion beam (FIB) milling is the typical way in which micro-pillars are fabricated to study small-scale plasticity and size effects in uniaxial compression. However, FIB milling can introduce defects into the milled pillars. To investigate the effects of FIB damage on mechanical behavior, we tested Mo-alloy micro-pillars that were FIB milled following directional solidification, and compared their compressive response to pillars that were not FIB milled. We also FIB milled at glancing incidence a Mo-alloy single-crystal surface, and compared its nanoindentation response to an electro-polished surface of the same crystal. Consequences for the interpretation of data obtained from FIB milled micro-pillars are discussed

  6. Thickness-modulated tungsten-carbon superconducting nanostructures grown by focused ion beam induced deposition for vortex pinning up to high magnetic fields.

    Science.gov (United States)

    Serrano, Ismael García; Sesé, Javier; Guillamón, Isabel; Suderow, Hermann; Vieira, Sebastián; Ibarra, Manuel Ricardo; De Teresa, José María

    2016-01-01

    We report efficient vortex pinning in thickness-modulated tungsten-carbon-based (W-C) nanostructures grown by focused ion beam induced deposition (FIBID). By using FIBID, W-C superconducting films have been created with thickness modulation properties exhibiting periodicity from 60 to 140 nm, leading to a strong pinning potential for the vortex lattice. This produces local minima in the resistivity up to high magnetic fields (2.2 T) in a broad temperature range due to commensurability effects between the pinning potential and the vortex lattice. The results show that the combination of single-step FIBID fabrication of superconducting nanostructures with built-in artificial pinning landscapes and the small intrinsic random pinning potential of this material produces strong periodic pinning potentials, maximizing the opportunities for the investigation of fundamental aspects in vortex science under changing external stimuli (e.g., temperature, magnetic field, electrical current).

  7. Post-focus expansion of ion beams for low fluence and large area MeV ion irradiation: Application to human brain tissue and electronics devices

    Science.gov (United States)

    Whitlow, Harry J.; Guibert, Edouard; Jeanneret, Patrick; Homsy, Alexandra; Roth, Joy; Krause, Sven; Roux, Adrien; Eggermann, Emmanuel; Stoppini, Luc

    2017-08-01

    Irradiation with ∼3 MeV proton fluences of 106-109 protons cm-2 have been applied to study the effects on human brain tissue corresponding to single-cell irradiation doses and doses received by electronic components in low-Earth orbit. The low fluence irradiations were carried out using a proton microbeam with the post-focus expansion of the beam; a method developed by the group of Breese [1]. It was found from electrophysiological measurements that the mean neuronal frequency of human brain tissue decreased to zero as the dose increased to 0-1050 Gy. Enhancement-mode MOSFET transistors exhibited a 10% reduction in threshold voltage for 2.7 MeV proton doses of 10 Gy while a NPN bipolar transistor required ∼800 Gy to reduce the hfe by 10%, which is consistent the expected values.

  8. Optimizing a neutron-beam focusing device for the direct geometry time-of-flight spectrometer TOFTOF at the FRM II reactor source

    DEFF Research Database (Denmark)

    Rasmussen, N. G.; Simeoni, G. G.; Lefmann, K.

    2016-01-01

    (adjustable supermirror curvature) and the compact size (only 0.5 m long). We have simulated the neutron transport across the entire guide system. We present a detailed computer characterization of the existing device, along with the study of the factors mostly influencing the future improvement. We have......, and the ability of a variable curvature to keep the focal point at the sample position. Our simulations are in excellent agreement with theoretical predictions and the experimentally measured beam profile. With respect to the possibility of a further upgrade, we find that supermirror coatings with m-values higher...... than 3.5 would have only marginal influence on the optimal behaviour, whereas comparable spectrometers could take advantage of longer focusing segments, with particular impact for the thermal region of the neutron spectrum....

  9. The rapid prototyping of textured amorphous surfaces for the graphoepitaxial deposition of CdTe films using focused ion beam lithography

    Energy Technology Data Exchange (ETDEWEB)

    Neretina, S. [McMaster University, Department of Engineering Physics and Centre for Emerging Device Technologies, Hamilton, Ontario (Canada); Temple University, Department of Mechanical Engineering, Philadelphia, PA (United States); Hughes, R.A. [McMaster University, Brockhouse Institute for Materials Research, Hamilton, Ontario (Canada); Temple University, Department of Mechanical Engineering, Philadelphia, PA (United States); Stortz, G.; Mascher, P. [McMaster University, Department of Engineering Physics and Centre for Emerging Device Technologies, Hamilton, Ontario (Canada); Preston, J.S. [McMaster University, Department of Engineering Physics and Centre for Emerging Device Technologies, Hamilton, Ontario (Canada); McMaster University, Brockhouse Institute for Materials Research, Hamilton, Ontario (Canada)

    2011-02-15

    Cadmium telluride films deposited on amorphous substrates exhibit a grain structure characterized by [111]-oriented grains, but where the in-plane grain orientation is randomized due to the absence of epitaxy. Here, we explore the viability of promoting an in-plane grain alignment through graphoepitaxy. Fifteen different substrate surface textures were fabricated using focused ion beam lithography. This approach allows for the side-by-side deposition of surface textures where both the areal extent and depth of the surface features are varied in a systematic manner. CdTe films deposited overtop these textures show grain structures with dramatic variations, revealing that particular length scales have the most pronounced effect on the grain structure. (orig.)

  10. Selective area growth of InAs nanowires from SiO2/Si(1 1 1) templates direct-written by focused helium ion beam technology

    Science.gov (United States)

    Yang, Che-Wei; Chen, Wei-Chieh; Chou, Chieh; Lin, Hao-Hsiung

    2018-02-01

    We report on the selective area growth of InAs nanowires on patterned SiO2/Si (1 1 1) nano-holes, prepared by focused helium ion beam technology. We used a single spot mode, in which the focused helium ion beam was fixed on a single point with a He+-ion dosage, ranging from 1.5 pC to 8 pC, to drill the nano-holes. The smallest hole diameter achieved is ∼8 nm. We found that low He+-ion dosage is able to facilitate the nucleation of (1 1 1)B InAs on the highly mismatched Si, leading to the vertical growth of InAs nanowires (NWs). High He-ion dosage, on the contrary, severely damaged Si surface, resulting in tilted and stripe-like NWs. In addition to titled NW grown from (1 1 1)A InAs domain, a new titled growth direction due to defect induced twinning was observed. Cross-sectional TEM images of vertical NWs show mixed wurtizite (WZ) and zincblende (ZB) phases, while WZ phase dominants. The stacking faults resulting from the phase change is proportional to NW diameter, suggesting that the critical diameter of phase turning is larger than 110 nm, the maximum diameter of our NWs. Period of misfit dislocation at the InAs/Si interface of vertical NW is also found larger than the theoretical value when the diameter of heterointerface is smaller than 50 nm, indicating that the small contact area is able to accommodate the large lattice and thermal mismatch between InAs and Si.

  11. Fabrication of FeSi and Fe{sub 3}Si compounds by electron beam induced mixing of [Fe/Si]{sub 2} and [Fe{sub 3}/Si]{sub 2} multilayers grown by focused electron beam induced deposition

    Energy Technology Data Exchange (ETDEWEB)

    Porrati, F.; Sachser, R.; Huth, M. [Physikalisches Institut, Goethe-Universität, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany); Gazzadi, G. C. [S3 Center, Nanoscience Institute-CNR, Via Campi 213/a, 41125 Modena (Italy); Frabboni, S. [S3 Center, Nanoscience Institute-CNR, Via Campi 213/a, 41125 Modena (Italy); FIM Department, University of Modena and Reggio Emilia, Via G. Campi 213/a, 41125 Modena (Italy)

    2016-06-21

    Fe-Si binary compounds have been fabricated by focused electron beam induced deposition by the alternating use of iron pentacarbonyl, Fe(CO){sub 5}, and neopentasilane, Si{sub 5}H{sub 12} as precursor gases. The fabrication procedure consisted in preparing multilayer structures which were treated by low-energy electron irradiation and annealing to induce atomic species intermixing. In this way, we are able to fabricate FeSi and Fe{sub 3}Si binary compounds from [Fe/Si]{sub 2} and [Fe{sub 3}/Si]{sub 2} multilayers, as shown by transmission electron microscopy investigations. This fabrication procedure is useful to obtain nanostructured binary alloys from precursors which compete for adsorption sites during growth and, therefore, cannot be used simultaneously.

  12. Comparison of ultramicrotomy and focused-ion-beam for the preparation of TEM and STEM cross section of organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Corazza, Michael, E-mail: michael.corazza@gmail.com [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde (Denmark); Simonsen, Søren B. [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde (Denmark); Gnaegi, Helmut [Diatome Ltd., Biel-Bienne (Switzerland); Thydén, Karl T.S.; Krebs, Frederik C.; Gevorgyan, Suren A. [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde (Denmark)

    2016-12-15

    Highlights: • Comparison of flexible solar cell sections prepared by ultramicrotomy and by FIB. • Energy filtered TEM analysis of phase separation in the P3HT:PCBM active layer. • Imaging of aging effects on solar cell cross section prepared by ultramicrotomy. • Ultramicrotomy provides great details while FIB better preserves the structure. - Abstract: The challenge of preparing cross sections of organic photovoltaics (OPV) suitable for transmission electron microscopy (TEM) and scanning TEM (STEM) is addressed. The samples were polymer solar cells fabricated using roll-to-roll (R2R) processing methods on a flexible polyethylene terephthalate (PET) substrate. Focused ion beam (FIB) and ultramicrotomy were used to prepare the cross sections. The differences between the samples prepared by ultramicrotomy and FIB are addressed, focusing on the advantages and disadvantages of each technique. The sample prepared by ultramicrotomy yielded good resolution, enabling further studies of phase separation of P3HT:PCBM by means of energy filtered TEM (EFTEM). The sample prepared by FIB shows good structure preservation, but reduced resolution due to non-optimal thicknesses achieved after treatment. Degradation studies of samples prepared by ultramicrotomy are further discussed, which reveal particular effects of the ISOS-L-3 aging test (85 °C, 50% R.H., 0.7 Sun) onto the sample, especially pronounced in the silver layer.

  13. Polycrystal model of the mechanical behavior of a Mo–TiC30vol.% metal–ceramic composite using a three-dimensional microstructure map obtained by dual beam focused ion beam scanning electron microscopy

    International Nuclear Information System (INIS)

    Cédat, D.; Fandeur, O.; Rey, C.; Raabe, D.

    2012-01-01

    The mechanical behavior of a Mo–TiC 30vol.% ceramic–metal composite was investigated over a wide temperature range (25–700 °C). High-energy X-ray tomography was used to reveal percolation of the hard titanium carbide phase through the composite. Using a polycrystal approach for a two-phase material, finite-element simulations were performed on a real three-dimensional (3-D) aggregate of the material. The 3-D microstructure, used as the starting configuration for the predictions, was obtained by serial sectioning in a dual beam focused ion beam scanning electron microscope coupled to an electron backscattered diffraction system. The 3-D aggregate consists of a molybdenum matrix and a percolating TiC skeleton. As for most body-centered cubic (bcc) metals, the molybdenum matrix phase is characterized by a change in plasticity mechanism with temperature. We used a polycrystal model for bcc materials which was extended to two phases (TiC and Mo). The model parameters of the matrix were determined from experiments on pure molydenum. For all temperatures investigated the TiC particles were considered to be brittle. Gradual damage to the TiC particles was treated, based on an accumulative failure law that is approximated by evolution of the apparent particle elastic stiffness. The model enabled us to determine the evolution of the local mechanical fields with deformation and temperature. We showed that a 3-D aggregate representing the actual microstructure of the composite is required to understand the local and global mechanical properties of the composite studied.

  14. Focused-ion-beam-fabricated Au nanorods coupled with Ag nanoparticles used as surface-enhanced Raman scattering-active substrate for analyzing trace melamine constituents in solution

    International Nuclear Information System (INIS)

    Sivashanmugan, Kundan; Liao, Jiunn-Der; Liu, Bernard Haochih; Yao, Chih-Kai

    2013-01-01

    Graphical abstract: -- Highlights: •Well-ordered Au-nanorod array with a controlled tip ring diameter (Au N Rs d ) is made by focused ion beam. •Au N Rs d coupled with Ag nanoparticles (Ag NPs/Au N Rs d ) is competent to sense target molecules in a solution. •Ag NPs/Au N Rs d SERS active substrate can detect a single molecule of crystal violet. •Ag NPs/Au N Rs d as a SERS-active substrate can distinguish melamine contaminants at low concentrations (e.g., 10 −12 M). -- Abstract: A well-ordered Au-nanorod array with a controlled tip ring diameter (Au N Rs d ) was fabricated using the focused ion beam method. Au N Rs d was then coupled with Ag nanoparticles (Ag NPs) to bridge the gaps among Au nanorods. The effect of surface-enhanced Raman scattering (SERS) on Au N Rs d and Ag NPs/Au N Rs d was particularly verified using crystal violet (CV) as the molecular probe. Raman intensity obtained from a characteristic peak of CV on Au N Rs d was estimated by an enhancement factor of ≈10 7 in magnitude, which increased ≈10 12 in magnitude for that on Ag NPs/Au N Rs d . A highly SERS-active Ag NPs/Au N Rs d was furthermore applied for the detection of melamine (MEL) at very low concentrations. Raman-active peaks of MEL (10 −3 to 10 −12 M) in water or milk solution upon Au N Rs d or Ag NPs/Au N Rs d were well distinguished. The peaks at 680 and 702 cm −1 for MEL molecules were found suitable to be used as the index for sensing low-concentration MEL in a varied solution, while that at 1051 cm −1 was practical to interpret MEL molecules in water or milk solution bonded with Au (i.e., Au N Rs d ) or Ag (i.e., Ag NPs/Au N Rs d ) surface. At the interface of Ag NPs/Au N Rs d and MEL molecules in milk solution, a laser-induced electromagnetic field or hotspot effect was produced and competent to sense low-concentration MEL molecules interacting with Ag and Au surfaces. Accordingly, Ag NPs/Au N Rs d is very promising to be used as a fast and sensitive tool for

  15. Fine chemistry

    International Nuclear Information System (INIS)

    Laszlo, P.

    1988-01-01

    The 1988 progress report of the Fine Chemistry laboratory (Polytechnic School, France) is presented. The research programs are centered on the renewal of the organic chemistry most important reactions and on the invention of new, highly efficient and highly selective reactions, by applying low cost reagents and solvents. An important research domain concerns the study and fabrication of new catalysts. They are obtained by means of the reactive sputtering of the metals and metal oxydes thin films. The Monte Carlo simulations of the long-range electrostatic interaction in a clay and the obtention of acrylamides from anhydrous or acrylic ester are summarized. Moreover, the results obtained in the field of catalysis are also given. The published papers and the congress communications are included [fr

  16. Characterisation of strip silicon detectors for the ATLAS Phase-II Upgrade with a micro-focused X-ray beam

    CERN Document Server

    INSPIRE-00407830; Blue, Andrew; Bates, Richard; Bloch, Ingo; Diez, Sergio; Fernandez-Tejero, Javier; Fleta, Celeste; Gallop, Bruce; Greenall, Ashley; Gregor, Ingrid-Maria; Hara, Kazuhiko; Ikegami, Yoichi; Lacasta, Carlos; Lohwasser, Kristin; Maneuski, Dzmitry; Nagorski, Sebastian; Pape, Ian; Phillips, Peter W.; Sperlich, Dennis; Sawhney, Kawal; Soldevila, Urmila; Ullan, Miguel; Unno, Yoshinobu; Warren, Matt

    2016-07-29

    The planned HL-LHC (High Luminosity LHC) in 2025 is being designed to maximise the physics potential through a sizable increase in the luminosity, totalling 1x10^35 cm^-2 s^-1 after 10 years of operation. A consequence of this increased luminosity is the expected radiation damage at 3000 fb^-1, requiring the tracking detectors to withstand hadron equivalences to over 1x10^16 1 MeV neutrons per cm^2. With the addition of increased readout rates, a complete re-design of the current ATLAS Inner Detector (ID) is being developed as the Inner Tracker (ITk). Two proposed detectors for the ATLAS strip tracker region of the ITk were characterized at the Diamond Light Source with a 3 micron FWHM 15 keV micro focused X-ray beam. The devices under test were a 320 micron thick silicon stereo (Barrel) ATLAS12 strip mini sensor wire bonded to a 130 nm CMOS binary readout chip (ABC130) and a 320 micron thick full size radial (Endcap) strip sensor - utilizing bi-metal readout layers - wire bonded to 250 nm CMOS binary readout...

  17. Internal architecture of coffin-shaped ZSM-5 zeolite crystals with hourglass contrast unravelled by focused ion beam-assisted transmission electron microscopy.

    Science.gov (United States)

    Lu, J; Bartholomeeusen, E; Sels, B F; Schryvers, D

    2017-01-01

    Optical microscopy, focused ion beam and transmission electron microscopy are combined to study the internal architecture in a coffin-shaped ZSM-5 crystal showing an hourglass contrast in optical microscopy. Based on parallel lamellas from different positions in the crystal, the orientation relationships between the intergrowth components of the crystal are studied and the internal architecture and growth mechanism are illustrated. The crystal is found to contain two pyramid-like components aside from a central component. Both pyramid-like components are rotated by 90° along the common c-axis and with respect to the central component while the interfaces between the components show local zig-zag feature, the latter indicating variations in relative growth velocity of the two components. The pyramid-like intergrowth components are larger and come closer to one another in the middle of the crystal than at the edges, but they do not connect. A model of multisite nucleation and growth of 90° intergrowth components is proposed. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

  18. Application of In-line Focused Beam Reflectance Measurement to Brivanib Alaninate Wet Granulation Process to Enable Scale-up and Attribute-based Monitoring and Control Strategies.

    Science.gov (United States)

    Narang, Ajit S; Stevens, Timothy; Macias, Kevin; Paruchuri, Srinivasa; Gao, Zhihui; Badawy, Sherif

    2017-01-01

    Application of in-line real-time process monitoring using a process analytical technology for granule size distribution can enable quality-by-design development of a drug product and enable attribute-based monitoring and control strategies. In this study, an in-line laser focused beam reflectance measurement (FBRM) C35 probe was used to investigate the effect of formulation and process parameters on the granule growth profile over time during the high shear wet granulation of a high drug load formulation of brivanib alaninate. The probe quantitatively captured changes in the granule chord length distribution (CLD) with the progress of granulation and delineated the impact of water concentration used during granulation. The results correlated well with offline particle size distribution measured by nested sieve analyses. An end point indication algorithm was developed that was able to successfully track the process time needed to reach the target CLD. Testing of the brivanib alaninate granulation through 25-fold scale-up of the batch process indicated that the FBRM CLD profile can provide a scale-independent granule attribute-based process fingerprint. These studies highlight the ability of FBRM to quantitate a granule attribute of interest during wet granulation that can be used as an attribute-based scale-up and process monitoring and control parameter. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  19. Analysis of shape and spatial interaction of synaptic vesicles using data from focused ion beam scanning electron microscopy (FIB-SEM

    Directory of Open Access Journals (Sweden)

    Mahdieh eKhanmohammadi

    2015-09-01

    Full Text Available The spatial interactions of synaptic vesicles in synapses were assessed after a detailed characterization of size, shape, and orientation of the synaptic vesicles. We hypothesized that shape and orientation of the synaptic vesicles are influenced by their movement towards the active zone causing deviations from spherical shape and systematic trends in their orientation.We studied three-dimensional representations of synapses obtained by manual annotation of focused ion beam scanning electron microscopy (FIB-SEM images of male mouse brain. The configurations of synaptic vesicles were regarded as marked point patterns, where the points are the centers of the vesicles, and the mark of a vesicle is given by its size, shape, and orientation characteristics. Statistics for marked point processes were employed to study spatial interactions between vesicles.We found that the synaptic vesicles in excitatory synapses appeared to be of oblate ellipsoid shape and in inhibitory synapses appeared to be of cigar ellipsoid shape, and followed a systematic pattern regarding their orientation towards the active zone. Moreover, there was strong evidence of spatial alignment in the orientations of pairs of synaptic vesicles, and of repulsion between them, beyond that caused by their physical extent.

  20. Understanding the crack formation of graphite particles in cycled commercial lithium-ion batteries by focused ion beam - scanning electron microscopy

    Science.gov (United States)

    Lin, Na; Jia, Zhe; Wang, Zhihui; Zhao, Hui; Ai, Guo; Song, Xiangyun; Bai, Ying; Battaglia, Vincent; Sun, Chengdong; Qiao, Juan; Wu, Kai; Liu, Gao

    2017-10-01

    The structure degradation of commercial Lithium-ion battery (LIB) graphite anodes with different cycling numbers and charge rates was investigated by focused ion beam (FIB) and scanning electron microscopy (SEM). The cross-section image of graphite anode by FIB milling shows that cracks, resulted in the volume expansion of graphite electrode during long-term cycling, were formed in parallel with the current collector. The crack occurs in the bulk of graphite particles near the lithium insertion surface, which might derive from the stress induced during lithiation and de-lithiation cycles. Subsequently, crack takes place along grain boundaries of the polycrystalline graphite, but only in the direction parallel with the current collector. Furthermore, fast charge graphite electrodes are more prone to form cracks since the tensile strength of graphite is more likely to be surpassed at higher charge rates. Therefore, for LIBs long-term or high charge rate applications, the tensile strength of graphite anode should be taken into account.

  1. Site-Specific Preparation of Intact Solid-Liquid Interfaces by Label-Free In Situ Localization and Cryo-Focused Ion Beam Lift-Out.

    Science.gov (United States)

    Zachman, Michael J; Asenath-Smith, Emily; Estroff, Lara A; Kourkoutis, Lena F

    2016-12-01

    Scanning transmission electron microscopy (STEM) allows atomic scale characterization of solid-solid interfaces, but has seen limited applications to solid-liquid interfaces due to the volatility of liquids in the microscope vacuum. Although cryo-electron microscopy is routinely used to characterize hydrated samples stabilized by rapid freezing, sample thinning is required to access the internal interfaces of thicker specimens. Here, we adapt cryo-focused ion beam (FIB) "lift-out," a technique recently developed for biological specimens, to prepare intact internal solid-liquid interfaces for high-resolution structural and chemical analysis by cryo-STEM. To guide the milling process we introduce a label-free in situ method of localizing subsurface structures in suitable materials by energy dispersive X-ray spectroscopy (EDX). Monte Carlo simulations are performed to evaluate the depth-probing capability of the technique, and show good qualitative agreement with experiment. We also detail procedures to produce homogeneously thin lamellae, which enable nanoscale structural, elemental, and chemical analysis of intact solid-liquid interfaces by analytical cryo-STEM. This work demonstrates the potential of cryo-FIB lift-out and cryo-STEM for understanding physical and chemical processes at solid-liquid interfaces.

  2. Comparison of the Chromium Distribution in New Super Koropon Primer to 30 Year Old Super Koropon Using Focused Ion Beam/Scanning Electron Microscopy

    Science.gov (United States)

    Lomness, Janice K.; Calle, Luz Marina

    2006-01-01

    Super Koropon primer (MB0125-055) plays a significant role in the corrosion protection of areas throughout the Orbiter. Because the Shuttle Program relies so heavily upon the performance of the Koropon primer, it is necessary to fully understand all aspects of the behavior of the coating. One area where little understanding of the Koropon primer still exists is the level of risk associated with age related degradation. Recently, efforts were undertaken to better understand the age life of the Koropon primer and to gain some insight into the aging process of this coating. In that study, an aluminum access panel from the Orbiter Enterprise was used to investigate the performance of the old Koropon film. A control panel was also used to study the performance of new Koropon coating. Preliminary investigations into the performance of aged Super Koropon primer indicated a significant decrease in corrosion protection. This investigation serves as an example of how Focused Ion Beam/Scanning Microscopy can be used to characterize the changes that occur as coatings age.

  3. A focused ion beam milling and lift-out approach for site-specific preparation of frozen-hydrated lamellas from multicellular organisms.

    Science.gov (United States)

    Mahamid, Julia; Schampers, Ruud; Persoon, Hans; Hyman, Anthony A; Baumeister, Wolfgang; Plitzko, Jürgen M

    2015-11-01

    Cryo-electron tomography provides 3D views of cellular architecture with molecular resolution. A principal limitation of cryo-transmission electron microscopy performed on cells or tissues is the accessible specimen thickness. Recently it has been shown that cryo-focused ion beam milling of plunge-frozen eukaryotic cells can produce homogeneously thin, distortion free lamellas for cryo-electron tomography. Multicellular organisms and tissue cannot be properly vitrified and thinned using this technique because they are considerably thicker. High pressure freezing is therefore necessary to provide optimal preservation. Here, we describe a workflow for preparing lamellas from Caenorhabditis elegans worms using cryo-FIB applied to high pressure frozen samples. We employ cryo-planing followed by correlative cryo-fluorescence microscopy to navigate this large multicellular volume and to localize specific targets within. To produce vitreous lamellas amenable to cryo-TEM observations at these targeted locations, we have developed a dedicated lift-out procedure at cryogenic temperature. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. I. The theory of aberrations of quadrupole focusing arrays. II. Ion optical design of high quality extracted synchrotron beams with application to the bevatron

    Energy Technology Data Exchange (ETDEWEB)

    Meads, Jr, Philip Francis [Univ. of California, Berkeley, CA (United States). Applied Science and Technology

    1963-05-15

    In Part One they formulate in a general way the problem of analyzing and evaluating the aberrations of quadrupole magnet beam systems, and of characterizing the shapes and other properties of the beam envelopes in the neighborhood of foci. They consider all aberrations, including those due to misalignments and faulty construction, through third order in small parameters, for quadrupole beam systems. One result of this study is the development of analytic and numerical techniques for treating these aberrations, yielding useful expressions for the comparison of the aberrations of different beam systems. A second result of this study is a comprehensive digital computer program that determines the magnitude and nature of the aberrations of such beam systems. The code, using linear programming techniques, will adjust the parameters of a beam system to obtain specified optical properties and to reduce the magnitude of aberrations that limit the performance of that system. They examine numerically, in detail, the aberrations of two typical beam systems. In Part Two, they examine the problem of extracting the proton beam from a synchrotron of 'H' type magnet construction. They describe the optical studies that resulted in the design of an external beam from the Bevatron that is optimized with respect to linear, dispersive, and aberration properties and that uses beam elements of conservative design. The design of the beam is the result of the collaboration of many people representing several disciplines. They describe the digital computer programs developed to carry out detailed orbit studies which were required because of the existence of large second order aberrations in the beam.

  5. Beam loss caused by edge focusing of injection bump magnets and its mitigation in the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex

    Directory of Open Access Journals (Sweden)

    H. Hotchi

    2016-01-01

    Full Text Available In the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex, transverse injection painting is utilized not only to suppress space-charge induced beam loss in the low energy region but also to mitigate foil scattering beam loss during charge-exchange injection. The space-charge induced beam loss is well minimized by the combination of modest transverse painting and full longitudinal painting. But, for sufficiently mitigating the foil scattering part of beam loss, the transverse painting area has to be further expanded. However, such a wide-ranging transverse painting had not been realized until recently due to beta function beating caused by edge focusing of pulsed injection bump magnets during injection. This beta function beating additionally excites random betatron resonances through a distortion of the lattice superperiodicity, and its resultant deterioration of the betatron motion stability causes significant extra beam loss when expanding the transverse painting area. To solve this issue, we newly installed pulse-type quadrupole correctors to compensate the beta function beating. This paper presents recent experimental results on this correction scheme for suppressing the extra beam loss, while discussing the beam loss and its mitigation mechanisms with the corresponding numerical simulations.

  6. Determining temperature distribution in tissue in the focal plane of the high (>100 W/cm(2)) intensity focused ultrasound beam using phase shift of ultrasound echoes.

    Science.gov (United States)

    Karwat, Piotr; Kujawska, Tamara; Lewin, Peter A; Secomski, Wojciech; Gambin, Barbara; Litniewski, Jerzy

    2016-02-01

    In therapeutic applications of High Intensity Focused Ultrasound (HIFU) the guidance of the HIFU beam and especially its focal plane is of crucial importance. This guidance is needed to appropriately target the focal plane and hence the whole focal volume inside the tumor tissue prior to thermo-ablative treatment and beginning of tissue necrosis. This is currently done using Magnetic Resonance Imaging that is relatively expensive. In this study an ultrasound method, which calculates the variations of speed of sound in the locally heated tissue volume by analyzing the phase shifts of echo-signals received by an ultrasound scanner from this very volume is presented. To improve spatial resolution of B-mode imaging and minimize the uncertainty of temperature estimation the acoustic signals were transmitted and received by 8 MHz linear phased array employing Synthetic Transmit Aperture (STA) technique. Initially, the validity of the algorithm developed was verified experimentally in a tissue-mimicking phantom heated from 20.6 to 48.6 °C. Subsequently, the method was tested using a pork loin sample heated locally by a 2 MHz pulsed HIFU beam with focal intensity ISATA of 129 W/cm(2). The temperature calibration of 2D maps of changes in the sound velocity induced by heating was performed by comparison of the algorithm-determined changes in the sound velocity with the temperatures measured by thermocouples located in the heated tissue volume. The method developed enabled ultrasound temperature imaging of the heated tissue volume from the very inception of heating with the contrast-to-noise ratio of 3.5-12 dB in the temperature range 21-56 °C. Concurrently performed, conventional B-mode imaging revealed CNR close to zero dB until the temperature reached 50 °C causing necrosis. The data presented suggest that the proposed method could offer an alternative to MRI-guided temperature imaging for prediction of the location and extent of the thermal lesion prior to applying the

  7. Portable test bench for the studies concerning ion sources and ion beam extraction and focusing systems; Banco de pruebas portatil para el estudio de fuentes de iones y de la extraccion y enfoque del haz de iones

    Energy Technology Data Exchange (ETDEWEB)

    Cordero Lopez, F.

    1961-07-01

    A portable test bench is described, which was designed to check ion sources, ion beam extraction and focusing systems before its use in a 600 KeV Cockcroft-Walton accelerator. The vacuum possibilities of the system are specially analyzed in connection with its particular use. The whole can be considered as a portable accelerator of low energy (50 keV). (Author)

  8. Investigating microstructural evolution during the electroreduction of UO{sub 2} to U in LiCl-KCl eutectic using focused ion beam tomography

    Energy Technology Data Exchange (ETDEWEB)

    Brown, L.D.; Abdulaziz, R.; Tjaden, B.; Inman, D.; Brett, D.J.L.; Shearing, P.R., E-mail: p.shearing@ucl.ac.uk

    2016-11-15

    Reprocessing of spent nuclear fuels using molten salt media is an attractive alternative to liquid-liquid extraction techniques. Pyroelectrochemical processing utilizes direct, selective, electrochemical reduction of uranium dioxide, followed by selective electroplating of a uranium metal. Thermodynamic prediction of the electrochemical reduction of UO{sub 2} to U in LiCl-KCl eutectic has shown to be a function of the oxide ion activity. The pO{sup 2−} of the salt may be affected by the microstructure of the UO{sub 2} electrode. A uranium dioxide filled “micro-bucket” electrode has been partially electroreduced to uranium metal in molten lithium chloride-potassium chloride eutectic. This partial electroreduction resulted in two distinct microstructures: a dense UO{sub 2} and a porous U metal structure were characterised by energy dispersive X-ray spectroscopy. Focused ion beam tomography was performed on five regions of this electrode which revealed an overall porosity ranging from 17.36% at the outer edge to 3.91% towards the centre, commensurate with the expected extent of reaction in each location. The pore connectivity was also seen to reduce from 88.32% to 17.86% in the same regions and the tortuosity through the sample was modelled along the axis of propagation of the electroreduction, which was seen to increase from a value of 4.42 to a value of infinity (disconnected pores). These microstructural characteristics could impede the transport of O{sup 2−} ions resulting in a change in the local pO{sup 2−} which could result in the inability to perform the electroreduction. - Highlights: • The microstructural evolution of the reduction from UO{sub 2} to U has been investigated. • The porosity and tortuosity is seen to change significantly during electroreduction. • Low porosity and high tortuosity associated with the UO{sub 2} phase may impede O{sup 2−} transport.

  9. Investigating microstructural evolution during the electroreduction of UO2 to U in LiCl-KCl eutectic using focused ion beam tomography

    Science.gov (United States)

    Brown, L. D.; Abdulaziz, R.; Tjaden, B.; Inman, D.; Brett, D. J. L.; Shearing, P. R.

    2016-11-01

    Reprocessing of spent nuclear fuels using molten salt media is an attractive alternative to liquid-liquid extraction techniques. Pyroelectrochemical processing utilizes direct, selective, electrochemical reduction of uranium dioxide, followed by selective electroplating of a uranium metal. Thermodynamic prediction of the electrochemical reduction of UO2 to U in LiCl-KCl eutectic has shown to be a function of the oxide ion activity. The pO2- of the salt may be affected by the microstructure of the UO2 electrode. A uranium dioxide filled "micro-bucket" electrode has been partially electroreduced to uranium metal in molten lithium chloride-potassium chloride eutectic. This partial electroreduction resulted in two distinct microstructures: a dense UO2 and a porous U metal structure were characterised by energy dispersive X-ray spectroscopy. Focused ion beam tomography was performed on five regions of this electrode which revealed an overall porosity ranging from 17.36% at the outer edge to 3.91% towards the centre, commensurate with the expected extent of reaction in each location. The pore connectivity was also seen to reduce from 88.32% to 17.86% in the same regions and the tortuosity through the sample was modelled along the axis of propagation of the electroreduction, which was seen to increase from a value of 4.42 to a value of infinity (disconnected pores). These microstructural characteristics could impede the transport of O2- ions resulting in a change in the local pO2- which could result in the inability to perform the electroreduction.

  10. Characterisation of silicon microstrip detectors for the ATLAS Phase-II Upgrade with a micro-focused X-ray beam

    Energy Technology Data Exchange (ETDEWEB)

    Poley, Luise [DESY, Hamburg (Germany); Blue, Andrew; Bates, Richard [Glasgow Univ. (United Kingdom). SUPA School of Physics and Astronomy; and others

    2016-03-15

    The planned HL-LHC (High Luminosity LHC) in 2025 is being designed to maximise the physics potential through a sizable increase in the luminosity, totalling 1 x 10{sup 35} cm{sup -2}s{sup -1} after 10 years of operation. A consequence of this increased luminosity is the expected radiation damage at 3000 fb{sup -1}, requiring the tracking detectors to withstand hadron equivalences to over 1 x 10{sup 16} 1 MeV neutrons per cm{sup 2}. With the addition of increased readout rates, a complete re-design of the current ATLAS Inner Detector (ID) is being developed as the Inner Tracker (ITk). Two proposed detectors for the ATLAS strip tracker region of the ITk were characterized at the Diamond Light Source with a 3 μm FWHM 15 keV micro focused X-ray beam. The devices under test were a 320 μm thick silicon stereo (Barrel) ATLAS12 strip mini sensor wire bonded to a 130 nm CMOS binary readout chip (ABC130) and a 320 μm thick full size radial (Endcap) strip sensor - utilizing bi-metal readout layers - wire bonded to 250 nm CMOS binary readout chips (ABCN-25). Sub-strip resolution of the 74.5 μm strips was achieved for both detectors. Investigation of the p-stop diffusion layers between strips is shown in detail for the wire bond pad regions. Inter strip charge collection measurements indicate that the effective width of the strip on the silicon sensors is determined by p-stops regions between the strips rather than the strip pitch. The collected signal allowed for the identification of operating thresholds for both devices, making it possible to compare signal response between different versions of silicon strip detector modules.

  11. Characterisation of strip silicon detectors for the ATLAS Phase-II Upgrade with a micro-focused X-ray beam

    Science.gov (United States)

    Poley, L.; Blue, A.; Bates, R.; Bloch, I.; Díez, S.; Fernandez-Tejero, J.; Fleta, C.; Gallop, B.; Greenall, A.; Gregor, I.-M.; Hara, K.; Ikegami, Y.; Lacasta, C.; Lohwasser, K.; Maneuski, D.; Nagorski, S.; Pape, I.; Phillips, P. W.; Sperlich, D.; Sawhney, K.; Soldevila, U.; Ullan, M.; Unno, Y.; Warren, M.

    2016-07-01

    The planned HL-LHC (High Luminosity LHC) in 2025 is being designed to maximise the physics potential through a sizable increase in the luminosity up to 6·1034 cm-2s-1. A consequence of this increased luminosity is the expected radiation damage at 3000 fb-1 after ten years of operation, requiring the tracking detectors to withstand fluences to over 1·1016 1 MeV neq/cm2. In order to cope with the consequent increased readout rates, a complete re-design of the current ATLAS Inner Detector (ID) is being developed as the Inner Tracker (ITk). Two proposed detectors for the ATLAS strip tracker region of the ITk were characterized at the Diamond Light Source with a 3 μm FWHM 15 keV micro focused X-ray beam. The devices under test were a 320 μm thick silicon stereo (Barrel) ATLAS12 strip mini sensor wire bonded to a 130 nm CMOS binary readout chip (ABC130) and a 320 μm thick full size radial (end-cap) strip sensor - utilizing bi-metal readout layers - wire bonded to 250 nm CMOS binary readout chips (ABCN-25). A resolution better than the inter strip pitch of the 74.5 μm strips was achieved for both detectors. The effect of the p-stop diffusion layers between strips was investigated in detail for the wire bond pad regions. Inter strip charge collection measurements indicate that the effective width of the strip on the silicon sensors is determined by p-stop regions between the strips rather than the strip pitch.

  12. Detailed characterisation of focused ion beam induced lateral damage on silicon carbide samples by electrical scanning probe microscopy and transmission electron microscopy

    Science.gov (United States)

    Stumpf, F.; Abu Quba, A. A.; Singer, P.; Rumler, M.; Cherkashin, N.; Schamm-Chardon, S.; Cours, R.; Rommel, M.

    2018-03-01

    The lateral damage induced by focused ion beam on silicon carbide was characterized using electrical scanning probe microscopy (SPM), namely, scanning spreading resistance microscopy and conductive atomic force microscopy (c-AFM). It is shown that the damage exceeds the purposely irradiated circles with a radius of 0.5 μm by several micrometres, up to 8 μm for the maximum applied ion dose of 1018 cm-2. Obtained SPM results are critically compared with earlier findings on silicon. For doses above the amorphization threshold, in both cases, three different areas can be distinguished. The purposely irradiated area exhibits resistances smaller than the non-affected substrate. A second region with strongly increasing resistance and a maximum saturation value surrounds it. The third region shows the transition from maximum resistance to the base resistance of the unaffected substrate. It correlates to the transition from amorphized to defect-rich to pristine crystalline substrate. Additionally, conventional transmission electron microscopy (TEM) and annular dark-field STEM were used to complement and explain the SPM results and get a further understanding of the defect spreading underneath the surface. Those measurements also show three different regions that correlate well with the regions observed from electrical SPM. TEM results further allow to explain observed differences in the electrical results for silicon and silicon carbide which are most prominent for ion doses above 3 × 1016 cm-2. Furthermore, the conventional approach to perform current-voltage measurements by c-AFM was critically reviewed and several improvements for measurement and analysis process were suggested that result in more reliable and impactful c-AFM data.

  13. Characterisation of silicon microstrip detectors for the ATLAS Phase-II Upgrade with a micro-focused X-ray beam

    International Nuclear Information System (INIS)

    Poley, Luise; Blue, Andrew; Bates, Richard

    2016-03-01

    The planned HL-LHC (High Luminosity LHC) in 2025 is being designed to maximise the physics potential through a sizable increase in the luminosity, totalling 1 x 10 35 cm -2 s -1 after 10 years of operation. A consequence of this increased luminosity is the expected radiation damage at 3000 fb -1 , requiring the tracking detectors to withstand hadron equivalences to over 1 x 10 16 1 MeV neutrons per cm 2 . With the addition of increased readout rates, a complete re-design of the current ATLAS Inner Detector (ID) is being developed as the Inner Tracker (ITk). Two proposed detectors for the ATLAS strip tracker region of the ITk were characterized at the Diamond Light Source with a 3 μm FWHM 15 keV micro focused X-ray beam. The devices under test were a 320 μm thick silicon stereo (Barrel) ATLAS12 strip mini sensor wire bonded to a 130 nm CMOS binary readout chip (ABC130) and a 320 μm thick full size radial (Endcap) strip sensor - utilizing bi-metal readout layers - wire bonded to 250 nm CMOS binary readout chips (ABCN-25). Sub-strip resolution of the 74.5 μm strips was achieved for both detectors. Investigation of the p-stop diffusion layers between strips is shown in detail for the wire bond pad regions. Inter strip charge collection measurements indicate that the effective width of the strip on the silicon sensors is determined by p-stops regions between the strips rather than the strip pitch. The collected signal allowed for the identification of operating thresholds for both devices, making it possible to compare signal response between different versions of silicon strip detector modules.

  14. Investigation of fatigue crack initiation facets in Ti-6Al-4V using focused ion beam milling and electron backscatter diffraction.

    Science.gov (United States)

    Everaerts, J; Verlinden, B; Wevers, M

    2017-07-01

    In the very high cycle fatigue regime, internal crack initiation can occur in Ti-6Al-4V because of the formation of facets, which are α grains that have fractured in a transcrystalline and planar manner. Because this crack initiation phase occupies most of the fatigue life, it is essential to understand which mechanisms lead to facet formation. Fatigue tests have been performed on drawn and heat-treated Ti-6Al-4V wires, and the facets at internal crack initiation sites have been analysed in detail in terms of their appearance, their spatial orientation and their crystallographic orientation. The facets were not smooth, but showed surface markings at the nanoscale. In nearly all cases, these markings followed a linear pattern. One anomalous facet, in a sample with the largest grain size, contained a fan-shaped pattern. The facets were at relatively steep angles, mostly between 50° and 70°. Cross-sections of the fracture surfaces have been made by focused ion beam milling and were used to measure the crystallographic orientation of facets by electron backscatter diffraction. Most facet planes coincided with a prismatic lattice plane, and the linear markings were parallel to the prismatic slip direction, which is a strong indication that prismatic slip and slip band formation led to crack initiation. However, the anomalous facet had a near-basal orientation, which points to a possible cleavage mechanism. The cross-sections also exposed secondary cracks, which had formed on prismatic lattice planes, and in some cases early stage facet formation and short crack growth phenomena. The latter observations show that facets can extend through more than one grain, and that there is crack coalescence between facets. The fact that drawn wires have a specific crystallographic texture has led to a different facet formation behaviour compared to what has been suggested in the literature. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  15. Self-focusing and filamentation of a laser beam within the paraxial stationary approximation. Part I: theoretical aspects; Autofocalisation et filamentation d`un faisceau laser dans le cadre de l`approximation paraxiale et stationnaire. Partie I: aspects theoriques

    Energy Technology Data Exchange (ETDEWEB)

    Blain, M.A.; Bonnaud, G.; Chiron, A.; Riazuelo, G.

    1996-02-01

    This report addresses the propagation of an intense laser beam in a unmagnetized plasma, which is relevant for both the inertial confinement fusion (ICF) and the ultra-high intensity (UHI) pulses. The width and the irradiance of the laser pulses are respectively: (0.1-10) nanosecond and (10{sup 13}-10{sup 16}) W/cm{sup 2} for the ICF context and (0.1-1) picosecond and in excess of 10{sup 18} W/cm{sup 2} for the UHI context. The nonlinear mechanisms for beam self-focusing and filamentation, induced by both the ponderomotive expelling of charged particles and the relativistic increase of the electron mass, are specified studied. Part I deals with the theoretical aspects and part II is concerned with the results of two-dimensional simulations. The results have been obtained within the framework of the paraxial approximation and the stationary response of the plasma. The large set of scenarios that characterize the behavior of Gaussian beam and a modulated beam is presented; a synthetic overview of the previous theoretical works is also provided. The interplay of two crossing beams is discussed. This report will be a help to improve the uniformity of the laser irradiation in the ICF context and to channel a very intense laser beam over large distance in the UHI context. (authors). 53 refs., 11 figs., 3 tabs.

  16. Self-focusing and filamentation of a laser beam within the paraxial stationary approximation. Part II: computer simulations; Autofocalisation et filamentation d`un faisceau laser dans le cadre de l`approximation paraxiale et stationnaire. Partie II: simulations numeriques

    Energy Technology Data Exchange (ETDEWEB)

    Blain, M.A.; Bonnaud, G.; Chiron, A.; Riazuelo, G.

    1996-02-01

    This report addresses the propagation of an intense laser beam in a unmagnetized plasma, which is relevant for both the inertial confinement fusion (ICF) and the ultra-high intensity (UHI) pulses. The width and the irradiance of the laser pulses are respectively: (0.1-10) nanosecond and (10{sup 13}-10{sup 16}) W/cm{sup 2} for the ICF context and (0.1-1) picosecond and in excess of 10{sup 1}8 W/cm{sup 2} for the UHI context. The nonlinear mechanisms for beam self-focusing and filamentation, induced by both the ponderomotive expelling of charged particles and the relativistic increase of the electron mass, are specified studied. Part I deals with the theoretical aspects and part II is concerned with the results of two-dimensional simulations. The results have been obtained within the framework of the paraxial approximation and the stationary response of the plasma. The large set of scenarios that characterize the behavior of Gaussian beam and a modulated beam is presented; a synthetic overview of the previous theoretical works is also provided. The interplay of two crossing beams is discussed. This report will be a help to improve the uniformity of the laser irradiation in the ICF context and to channel a very intense laser beam over large distance in the UHI context. (authors). 17 refs., 53 figs., 14 tabs.

  17. Centroid and Envelope Eynamics of Charged Particle Beams in an Oscillating Wobbler and External Focusing Lattice for Heavy Ion Fusion Applications

    International Nuclear Information System (INIS)

    Davidson, Ronald C.; Logan, B. Grant

    2011-01-01

    Recent heavy ion fusion target studies show that it is possible to achieve ignition with direct drive and energy gain larger than 100 at 1MJ. To realize these advanced, high-gain schemes based on direct drive, it is necessary to develop a reliable beam smoothing technique to mitigate instabilities and facilitate uniform deposition on the target. The dynamics of the beam centroid can be explored as a possible beam smoothing technique to achieve a uniform illumination over a suitably chosen region of the target. The basic idea of this technique is to induce an oscillatory motion of the centroid for each transverse slice of the beam in such a way that the centroids of different slices strike different locations on the target. The centroid dynamics is controlled by a set of biased electrical plates called 'wobblers'. Using a model based on moments of the Vlasov-Maxwell equations, we show that the wobbler deflection force acts only on the centroid motion, and that the envelope dynamics are independent of the wobbler fields. If the conducting wall is far away from the beam, then the envelope dynamics and centroid dynamics are completely decoupled. This is a preferred situation for the beam wobbling technique, because the wobbler system can be designed to generate the desired centroid motion on the target without considering its effects on the envelope and emittance. A conceptual design of the wobbler system for a heavy ion fusion driver is briefly summarized.

  18. A laser-based beam profile monitor for the SLC/SLD interaction region

    International Nuclear Information System (INIS)

    Alley, R.; Arnett, D.; Bong, E.; Colocho, W.; Frisch, J.; Horton-Smith, S.; Inman, W.; Jobe, K.; Kotseroglou, T.; McCormick, D.; Nelson, J.; Scheeff, M.; Wagner, S.; Ross, M.C.

    1996-01-01

    Beam size estimates made using beam-beam deflections are used for optimization of the Stanford linear collider (SLC) electron-positron beam sizes. Typical beam sizes and intensities expected for 1996 operations are 2.1 x 0.6 μm (x, y) at 4.0.10 10 particles per pulse. Conventional profile monitors, such as scanning wires, fail at charge densities well below this. The laser-based profile monitor uses a finely-focused 350-nm wavelength tripled YLF laser pulse that traverses the particle beam path about 29 cm away from the e + /e - IP. Compton scattered photons and degraded e + /e - are detected as the beam is steered across the laser pulse. The laser pulse has a transverse size of 380 nm and a Rayleigh range of about 5 μm. (orig.)

  19. Focusing horn

    CERN Multimedia

    1980-01-01

    This was the first magnetic horn developed by Simon Van der Meer to collect antiprotons in the AD complex. It was used for the AA (antiproton accumulator). Making an antiproton beam took a lot of time and effort. Firstly, protons were accelerated to an energy of 26 GeV/c (protons at 26GeV/c, antiprotons at 3.6GeV/c) in the PS and ejected onto a metal target. From the spray of emerging particles, a magnetic horn picked out 3.6 GeV antiprotons for injection into the AA through a wide-aperture focusing quadrupole magnet. For a million protons hitting the target, just one antiproton was captured, 'cooled' and accumulated. It took 3 days to make a beam of 3 x 10^11 -, three hundred thousand million - antiprotons. The development of this technology was a key step to the functioning of CERN's Super Proton Synchrotron as a proton - antiproton collider.

  20. Analysis of packing microstructure and wall effects in a narrow-bore ultrahigh pressure liquid chromatography column using focused ion-beam scanning electron microscopy.

    Science.gov (United States)

    Reising, Arved E; Schlabach, Sabine; Baranau, Vasili; Stoeckel, Daniela; Tallarek, Ulrich

    2017-09-01

    Column wall effects are well recognized as major limiting factor in achieving high separation efficiency in HPLC. This is especially important for modern analytical columns packed with small particles, where wall effects dominate the band broadening. Detailed knowledge about the packing microstructure of packed analytical columns has so far not been acquired. Here, we present the first three-dimensional reconstruction protocol for these columns utilizing focused ion-beam scanning electron microscopy (FIB-SEM) on a commercial 2.1mm inner diameter×50mm length narrow-bore analytical column packed with 1.7μm bridged-ethyl hybrid silica particles. Two sections from the packed bed are chosen for reconstruction by FIB-SEM: one from the bulk packing region of the column and one from its critical wall region. This allows quantification of structural differences between the wall region and the center of the bed due to effects induced by the hard, confining column wall. Consequences of these effects on local flow velocity in the column are analyzed with flow simulations utilizing the lattice-Boltzmann method. The reconstructions of the bed structures reveal significant structural differences in the wall region (extending radially over approximately 62 particle diameters) compared to the center of the column. It includes the local reduction of the external porosity by up to 10% and an increase of the mean particle diameter by up to 3%, resulting in a decrease of the local flow velocity by up to 23%. In addition, four (more ordered) layers of particles in the direct vicinity of the column wall induce local velocity fluctuations by up to a factor of three regarding the involved velocity amplitudes. These observations highlight the impact of radial variations in packing microstructure on band migration and column performance. This knowledge on morphological peculiarities of column wall effects helps guiding us towards further optimization of the packing process for analytical

  1. Strong-strong beam-beam simulation on parallel computer

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, Ji

    2004-08-02

    The beam-beam interaction puts a strong limit on the luminosity of the high energy storage ring colliders. At the interaction points, the electromagnetic fields generated by one beam focus or defocus the opposite beam. This can cause beam blowup and a reduction of luminosity. An accurate simulation of the beam-beam interaction is needed to help optimize the luminosity in high energy colliders.

  2. Strong-strong beam-beam simulation on parallel computer

    International Nuclear Information System (INIS)

    Qiang, Ji

    2004-01-01

    The beam-beam interaction puts a strong limit on the luminosity of the high energy storage ring colliders. At the interaction points, the electromagnetic fields generated by one beam focus or defocus the opposite beam. This can cause beam blowup and a reduction of luminosity. An accurate simulation of the beam-beam interaction is needed to help optimize the luminosity in high energy colliders

  3. Ion Accelerator Merges Several Beams

    Science.gov (United States)

    Aston, G.

    1984-01-01

    Intense ion beam formed by merging multiple ion beamlets into one concentrated beam. Beamlet holes in graphite screen and focusing grids arranged in hexagonal pattern. Merged beam passes through single hole in each of aluminum accelerator and decelerator grids. Ion extraction efficiency, beam intensity, and focusing improved.

  4. Observation of Muon Neutrino Charged Current Events in an Off-Axis Horn-Focused Neutrino Beam Using the NOvA Prototype Detector

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, Enrique Arrieta [Michigan State Univ., East Lansing, MI (United States)

    2014-01-01

    The NOνA is a long base-line neutrino oscillation experiment. It will study the oscillations between muon and electron neutrinos through the Earth. NOνA consists of two detectors separated by 810 km. Each detector will measure the electron neutrino content of the neutrino (NuMI) beam. Differences between the measurements will reveal details about the oscillation channel. The NOνA collaboration built a prototype detector on the surface at Fermilab in order to develop calibration, simulation, and reconstruction tools, using real data. This 220 ton detector is 110 mrad off the NuMI beam axis. This off-axis location allows the observation of neutrino interactions with energies around 2 GeV, where neutrinos come predominantly from charged kaon decays. During the period between October 2011 and April 2012, the prototype detector collected neutrino data from 1.67 × 1020 protons on target delivered by the NuMI beam. This analysis selected a number of candidate charged current muon neutrino events from the prototype data, which is 30% lower than predicted by the NOνA Monte Carlo simulation. The analysis suggests that the discrepancy comes from an over estimation of the neutrino flux in the Monte Carlo simulation, and in particular, from neutrinos generated in charged kaon decays. The ratio of measured divided by the simulated flux of muon neutrinos coming from charged kaon decays is: 0.70+0.108 -0.094. The NOνA collaboration may use the findings of this analysis to introduce a more accurate prediction of the neutrino flux produced by the NuMI beam in future Monte Carlo simulations.

  5. Beam halo in high-intensity beams

    International Nuclear Information System (INIS)

    Wangler, T.P.

    1993-01-01

    In space-charge dominated beams the nonlinear space-charge forces produce a filamentation pattern, which in projection to the 2-D phase spaces results in a 2-component beam consisting of an inner core and a diffuse outer halo. The beam-halo is of concern for a next generation of cw, high-power proton linacs that could be applied to intense neutron generators for nuclear materials processing. The author describes what has been learned about beam halo and the evolution of space-charge dominated beams using numerical simulations of initial laminar beams in uniform linear focusing channels. Initial results are presented from a study of beam entropy for an intense space-charge dominated beam

  6. An adiabatic focuser

    International Nuclear Information System (INIS)

    Chen, P.; Oide, K.; Sessler, A.M.; Yu, S.S.

    1989-08-01

    Theoretical analysis is made of an intense relativistic electron beam, such as would be available from a linear collider, moving through a plasma of increasing density, but density always less than that of the beam (underdense). In this situation, the plasma electrons are expelled from the beam channel and the electrons are subject to an ever-increasing focusing force provided by the channel ions. Analysis is made on the beam radiation energy loss in the classical, the transition, and the quantum regimes. It is shown that the focuser is insensitive to the beam energy spread behaviors in the nonclassical regimes, the radiation limit on lenses (the Oide limit) can be exceeded. The sensitivity of the system to the topic mismatch and the nonlinearity is also analyzed. Examples are given with SLC-type and TLC-type parameters. 9 refs., 1 tab

  7. Efficacy of 'fine' focal spot imaging in CT abdominal angiography

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Lawrence Chia Wei; Devapalasundaram, Ashwini; Ardley, Nicholas [Monash Health, Department of Diagnostic Imaging, Clayton, Victoria (Australia); Lau, Kenneth K. [Monash Health, Department of Diagnostic Imaging, Clayton, Victoria (Australia); Monash University, Department of Medicine, Faculty of Medicine, Nursing, and Health Sciences, Victoria (Australia); Buchan, Kevin [Phillips Healthcare, Clinical Science, PO Box 312, Mont Albert, Victoria (Australia); Huynh, Minh [RMIT University, School of Mathematical and Geospatial Sciences, Victoria (Australia)

    2014-12-15

    To assess the efficacy of fine focal spot imaging in calcification beam-hardening artefact reduction and vessel clarity on CT abdominal angiography (CTAA). Adult patients of any age and gender who presented for CTAA were included. Thirty-nine patients were examined with a standard focal spot size (SFSS) of 1 x 1 mm in the first 3 months while 31 consecutive patients were examined with a fine focal spot size (FFSS) of 1 x 0.5 mm in the following 3 months. Vessel clarity and calcification beam-hardening artefacts of the abdominal aorta, celiac axis, superior mesenteric artery, inferior mesenteric artery, renal arteries, and iliac arteries were assessed using a 5-point grading scale by two blinded radiologists randomly. Cohen's Kappa test indicated that on average, there was substantial agreement among reviewers for vessel wall clarity and calcification artefact grading. Mann-Whitney test showed that there was a significant difference between the two groups, with FFSS performing significantly better for vessel clarity (U, 6481.50; p < 0.001; r, 0.73) and calcification artefact reduction (U, 1916; p < 0.001; r, 0.77). Fine focus CT angiography produces images with better vessel wall clarity and less vessel calcification beam-hardening artefact. (orig.)

  8. Fiscal 1998 research report. Application technology of next-generation high-density energy beams; 1998 nendo chosa hokokusho. Jisedai komitsudo energy beam riyo gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    Survey was made on application technologies of next- generation high-density energy beams. For real application of laser power, application to not exciting source of YAG crystal but machining directly is highly efficient. For generation of semiconductor laser high-power coherent beam, phase synchronization and summing are large technological walls. Short pulse, high intensity and high repeatability are also important. Since ultra-short pulse laser ends before heat transfer to the periphery, it is suitable for precise machining, in particular, ultra-fine machining. To use beam sources as tool for production process, development of transmission, focusing and control technologies, and optical fiber and device is indispensable. Applicable fields are as follows: machining (more than pico seconds), surface modification (modification and functionalization of tribo- materials and biocompatible materials), complex machining, fabrication of quantum functional structured materials (thin film, ultra-fine particle), agriculture, ultra-precise measurement, non-destructive measurement, and coherent chemistry in chemical and environment fields. (NEDO)

  9. The Effect of Collimating Lens Focusing on Laser Beam Shape in Matrix Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS)

    Science.gov (United States)

    O'Rourke, Matthew B.; Raymond, Benjamin B. A.; Djordjevic, Steven P.; Padula, Matthew P.

    2018-01-01

    Tissue imaging using matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a well-established technique that, in recent years, has seen wider adoption and novel application. Applications such imaging mass spectrometry (IMS) and biotyping are beginning to gain greater exposure and use; however, with limitations in optimization methods, producing the best result often relies on the ability to customize the physical characteristics of the instrumentation, a task that is challenging for most mass spectrometry laboratories. With this in mind, we have described the effect of making simple adjustments to the laser optics at the final collimating lens area, to adjust the laser beam size and shape in order to allow greater customization of the instrument for improving techniques such as IMS. We have therefore been able to demonstrate that improvements can be made without requiring the help of an electrical engineer or external funding in a way that only costs a small amount of time.

  10. The Effect of Collimating Lens Focusing on Laser Beam Shape in Matrix Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS)

    Science.gov (United States)

    O'Rourke, Matthew B.; Raymond, Benjamin B. A.; Djordjevic, Steven P.; Padula, Matthew P.

    2018-03-01

    Tissue imaging using matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a well-established technique that, in recent years, has seen wider adoption and novel application. Applications such imaging mass spectrometry (IMS) and biotyping are beginning to gain greater exposure and use; however, with limitations in optimization methods, producing the best result often relies on the ability to customize the physical characteristics of the instrumentation, a task that is challenging for most mass spectrometry laboratories. With this in mind, we have described the effect of making simple adjustments to the laser optics at the final collimating lens area, to adjust the laser beam size and shape in order to allow greater customization of the instrument for improving techniques such as IMS. We have therefore been able to demonstrate that improvements can be made without requiring the help of an electrical engineer or external funding in a way that only costs a small amount of time.

  11. Contribution to the study of the {alpha} spectrometry by the impulse ionization chamber. Application to the study of the beam fine structure of some heavy nuclei; Contribution a l'etude de la spectrometrie {alpha} par la chambre d'ionisation a impulsion. Application a l'etude de la structure fine du rayonnement de quelques noyaux lourds

    Energy Technology Data Exchange (ETDEWEB)

    Valladas, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1954-05-15

    In the first part, it studies an impulse spectrometer of which the resolution and stability have been pushed to their maximum possibilities. It uses an ionization chamber because of its simple and steady functioning. The general characteristics and building of the ionization chamber are described. The electronic devices are described as well as the recording system. The theoretical study of the amplifier has allowed to reduce the amplitude dispersion from electronic devices as background noise. The resolution in energy of an {alpha} spectrometer using an impulse ionization chamber is studied and results are discussed. The spectral lines display of the fine structure under the effect of conversion electrons emitted by coincidence in the ionization chamber is studied. Finally, the detection possibilities of very low intensity spectral lines of fine structure of detection are considered. In the second part, the {alpha} emission of fine structure of {sup 230}Th, {sup 234}U and {sup 238}U nuclei is studied. (M.P.)

  12. T10 Beam Studies & Beam Simulation

    CERN Document Server

    Bergmann, Michael Georges; Van Dijk, Maarten; CERN. Geneva. EN Department

    2017-01-01

    In order to test detector components before their installation in actual experiments, one uses test beams in which one can control particle typ, momentum and size to high degree. For this project the focus of a secondary beam at T10 in the East Area at CERN was analysed using an AZALEA telescope from DESY.

  13. 3D Terahertz Beam Profiling

    DEFF Research Database (Denmark)

    Pedersen, Pernille Klarskov; Strikwerda, Andrew; Jepsen, Peter Uhd

    2013-01-01

    We present a characterization of THz beams generated in both a two-color air plasma and in a LiNbO3 crystal. Using a commercial THz camera, we record intensity images as a function of distance through the beam waist, from which we extract 2D beam profiles and visualize our measurements into 3D beam...... profiles. For the two-color air-plasma, we measure a conical beam profile that is focused to a bell-shape at the beam waist, whereas we observe a Gaussian beam profile for the THz beam generated from the LiNbO3 crystal....

  14. Line broadening by focusing

    International Nuclear Information System (INIS)

    Brito, A.L. de; Jabs, A.

    1983-01-01

    It is pointed out that the spectral width of a quasi-monochromatic light beam broadens when the beam is focused. A quantitative formula for this broadening is derived from classical wave theory. The effect is shown to explain some experiments on laser beams done by E. Panarella which that author has explained under the ad-hoc hypothesis that the frequency of the photons changes along with the intensity of the light beam. The line broadening by focusing might also contribute to gas ionization by incident light when the ionization potential is well above the mean photon energy. Some remarks are made on some direct applications of the Heisenberg relations in comparison with our treatment. (Author) [pt

  15. The Fine Structure Constant

    Indian Academy of Sciences (India)

    IAS Admin

    The article discusses the importance of the fine structure constant in quantum mechanics, along with the brief history of how it emerged. Al- though Sommerfelds idea of elliptical orbits has been replaced by wave mechanics, the fine struc- ture constant he introduced has remained as an important parameter in the field of ...

  16. [Aerodynamic focusing of particles and heavy molecules

    International Nuclear Information System (INIS)

    de la Mora, J.F.

    1990-01-01

    By accelerating a gas containing suspended particles or large molecules through a converging nozzle, the suspended species may be focused and therefore used to write fine lines on a surface. Our objective was to study the limits on how narrow this focal region could be as a function of particle size. We find that, for monodisperse particles with masses m p some 3.6 x 10 5 times larger than the molecular mass m of the carrier gas (diameters above some 100 angstrom), there is no fundamental obstacle to directly write submicron features. However, this conclusion has been verified experimentally only with particles larger than 0.1 μm. Experimental, theoretical and numerical studies on the defocusing role of Brownian motion for very small particles or heavy molecules have shown that high resolution (purely aerodynamic) focusing is impossible with volatile molecules whose masses are typically smaller than 1000 Dalton. For these, the minimal focal diameter after optimization appears to be 5√(m/m p ) times the nozzle diameter d n . But combinations of focused lasers and aerodynamic focusing appear as promising for direct writing with molecular precursors. Theoretical and numerical schemes capable of predicting the evolution of the focusing beam, including Brownian motion effects, have been developed, although further numerical work would be desirable. 11 refs

  17. Measurement of ion beam angular distribution at different helium gas pressures in a plasma focus device by large-area polycarbonate detectors

    Energy Technology Data Exchange (ETDEWEB)

    Sohrabi, M.; Habibi, M., E-mail: mortezahabibi@gmail.com; Ramezani, V. [Amirkabir University of Technology, Energy Engineering and Physics Department (Iran, Islamic Republic of)

    2017-02-15

    The paper presents an experimental study and analysis of full helium ion density angular distributions in a 4-kJ plasma focus device (PFD) at pressures of 10, 15, 25, and 30 mbar using large-area polycarbonate track detectors (PCTDs) (15-cm etchable diameter) processed by 50-Hz-HV electrochemical etching (ECE). Helium ion track distributions at different pressures, in particular, at the main axis of the PFD are presented. Maximum ion track density of ~4.4 × 10{sup 4} tracks/cm{sup 2} was obtained in the PCTD placed 6 cm from the anode. The ion distributions for all pressures applied are ring-shaped, which is possibly due to the hollow cylindrical copper anode used. The large-area PCTD processed by ECE proves, at the present state-of-theart, a superior method for direct observation and analysis of ion distributions at a glance with minimum efforts and time. Some observations of the ion density distributions at different pressures are reported and discussed.

  18. Beam-beam diagnostics from closed-orbit distortion

    Energy Technology Data Exchange (ETDEWEB)

    Furman, M.; Chin, Y.H.; Eden, J. [Lawrence Berkeley Lab., CA (United States); Kozanecki, W. [DAPNIA/SPP, CEN Saclay Gif-sur-Yvette, (FR)]|[Stanford Linear Accelerator Center, Menlo Park, CA (United States); Tennyson, J.; Ziemann, V. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1992-07-01

    We study the applicability of beam-beam deflection techniques as a tuning tool for asymmetric B factories, focusing on PEP-II as an example. Assuming that the closed orbits of the two beams are separated vertically at the interaction point by a local orbit bump that is nominally closed, we calculate the residual beam orbit distortions due to the beam-beam interaction. Difference orbit measurements, performed at points conveniently distant from the interaction point (IP), provide distinct signatures that can be used to maintain the beams in collision and perform detailed optical diagnostics at the IP. A proposal to test this method experimentally at the TRISTAN ring is briefly discussed.

  19. Neutral particle beam intensity controller

    Science.gov (United States)

    Dagenhart, W.K.

    1984-05-29

    The neutral beam intensity controller is based on selected magnetic defocusing of the ion beam prior to neutralization. The defocused portion of the beam is dumped onto a beam dump disposed perpendicular to the beam axis. Selective defocusing is accomplished by means of a magnetic field generator disposed about the neutralizer so that the field is transverse to the beam axis. The magnetic field intensity is varied to provide the selected partial beam defocusing of the ions prior to neutralization. The desired focused neutral beam portion passes along the beam path through a defining aperture in the beam dump, thereby controlling the desired fraction of neutral particles transmitted to a utilization device without altering the kinetic energy level of the desired neutral particle fraction. By proper selection of the magnetic field intensity, virtually zero through 100% intensity control of the neutral beam is achieved.

  20. Particle Accelerator Focus Automation

    Science.gov (United States)

    Lopes, José; Rocha, Jorge; Redondo, Luís; Cruz, João

    2017-08-01

    The Laboratório de Aceleradores e Tecnologias de Radiação (LATR) at the Campus Tecnológico e Nuclear, of Instituto Superior Técnico (IST) has a horizontal electrostatic particle accelerator based on the Van de Graaff machine which is used for research in the area of material characterization. This machine produces alfa (He+) and proton (H+) beams of some μA currents up to 2 MeV/q energies. Beam focusing is obtained using a cylindrical lens of the Einzel type, assembled near the high voltage terminal. This paper describes the developed system that automatically focuses the ion beam, using a personal computer running the LabVIEW software, a multifunction input/output board and signal conditioning circuits. The focusing procedure consists of a scanning method to find the lens bias voltage which maximizes the beam current measured on a beam stopper target, which is used as feedback for the scanning cycle. This system, as part of a wider start up and shut down automation system built for this particle accelerator, brings great advantages to the operation of the accelerator by turning it faster and easier to operate, requiring less human presence, and adding the possibility of total remote control in safe conditions.

  1. Particle Accelerator Focus Automation

    Directory of Open Access Journals (Sweden)

    Lopes José

    2017-08-01

    Full Text Available The Laboratório de Aceleradores e Tecnologias de Radiação (LATR at the Campus Tecnológico e Nuclear, of Instituto Superior Técnico (IST has a horizontal electrostatic particle accelerator based on the Van de Graaff machine which is used for research in the area of material characterization. This machine produces alfa (He+ and proton (H+ beams of some μA currents up to 2 MeV/q energies. Beam focusing is obtained using a cylindrical lens of the Einzel type, assembled near the high voltage terminal. This paper describes the developed system that automatically focuses the ion beam, using a personal computer running the LabVIEW software, a multifunction input/output board and signal conditioning circuits. The focusing procedure consists of a scanning method to find the lens bias voltage which maximizes the beam current measured on a beam stopper target, which is used as feedback for the scanning cycle. This system, as part of a wider start up and shut down automation system built for this particle accelerator, brings great advantages to the operation of the accelerator by turning it faster and easier to operate, requiring less human presence, and adding the possibility of total remote control in safe conditions.

  2. Fine Arts Database (FAD)

    Data.gov (United States)

    General Services Administration — The Fine Arts Database records information on federally owned art in the control of the GSA; this includes the location, current condition and information on artists.

  3. Analyses of fine paste ceramics

    International Nuclear Information System (INIS)

    Sabloff, J.A.

    1980-01-01

    Four chapters are included: history of Brookhaven fine paste ceramics project, chemical and mathematical procedures employed in Mayan fine paste ceramics project, and compositional and archaeological perspectives on the Mayan fine paste ceramics

  4. Analyses of fine paste ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sabloff, J A [ed.

    1980-01-01

    Four chapters are included: history of Brookhaven fine paste ceramics project, chemical and mathematical procedures employed in Mayan fine paste ceramics project, and compositional and archaeological perspectives on the Mayan fine paste ceramics. (DLC)

  5. High harmonics focusing undulator

    Energy Technology Data Exchange (ETDEWEB)

    Varfolomeev, A.A.; Hairetdinov, A.H.; Smirnov, A.V.; Khlebnikov, A.S. [Kurchatov Institute, Moscow (Russian Federation)

    1995-12-31

    It was shown in our previous work that there exist a possibility to enhance significantly the {open_quote}natural{close_quote} focusing properties of the hybrid undulator. Here we analyze the actual undulator configurations which could provide such field structure. Numerical simulations using 2D code PANDIRA were carried out and the enhanced focusing properties of the undulator were demonstrated. The obtained results provide the solution for the beam transport in a very long (short wavelength) undulator schemes.

  6. Hard X-ray nanofocusing using adaptive focusing optics based on piezoelectric deformable mirrors.

    Science.gov (United States)

    Goto, Takumi; Nakamori, Hiroki; Kimura, Takashi; Sano, Yasuhisa; Kohmura, Yoshiki; Tamasaku, Kenji; Yabashi, Makina; Ishikawa, Tetsuya; Yamauchi, Kazuto; Matsuyama, Satoshi

    2015-04-01

    An adaptive Kirkpatrick-Baez mirror focusing optics based on piezoelectric deformable mirrors was constructed at SPring-8 and its focusing performance characteristics were demonstrated. By adjusting the voltages applied to the deformable mirrors, the shape errors (compared to a target elliptical shape) were finely corrected on the basis of the mirror shape determined using the pencil-beam method, which is a type of at-wavelength figure metrology in the X-ray region. The mirror shapes were controlled with a peak-to-valley height accuracy of 2.5 nm. A focused beam with an intensity profile having a full width at half maximum of 110 × 65 nm (V × H) was achieved at an X-ray energy of 10 keV.

  7. Crystalline beams

    International Nuclear Information System (INIS)

    Schiffer, J.P.

    1989-01-01

    Ions in a storage ring are confined to a mean orbit by focusing elements. To a first approximation these may be described by a constant harmonic restoring force: F = -Kr. If the particles in the frame moving along with the beam have small random thermal energies, then they will occupy a cylindrical volume around the mean orbit and the focusing force will be balanced by that from the mutual repulsion of the particles. Inside the cylinder only residual two-particle interactions will play a significant role and some form of ordering might be expected to take place. The results of some of the first MD calculations showed a surprising result: not only were the particles arranged in the form of a tube, but they formed well-defined layers: concentric shells, with the particles in each shell arranged in a hexagonal lattice that is characteristic of two-dimensional Coulomb systems. This paper discusses the condense layer structure

  8. Focused ion beam systems: basics and applications

    National Research Council Canada - National Science Library

    Yao, Nan

    2007-01-01

    ..., their interaction with materials, etching, and deposition are all covered, as well as in-situ materials characterization, sample preparation, three-dimension reconstruction, and applications in biomaterials and nanotechnology. With nanostructured materials becoming increasingly important in micromechanical, electronic, and magnetic devices, this self...

  9. Increasing the mechanical strength of fine-grained concrete by introducing finely dispersed mineral additives

    Science.gov (United States)

    Khakimullina, Svetlana; Il'ina, Liliia; Mukhina, Irina

    2017-01-01

    The paper investigates the influence of particles size and the quantity of mineral additives, both active and inert, on the strength of fine-grained concrete. Concentrations of fine silica fume and diopside for maximum hardening of fine-grained concrete with a given size of input particles were determined experimentally. The strength properties of fine-grained concrete were detected by testing the sample beams with dimensions of 40×40×160 mm after 28 days of hardening under normal conditions. The results show that adding silica fume in the amount of 12% increases the compressive strength of concrete up to 55%; 7% of diopside with 52.5 microns dispersion - up to 46.7%; 3% of diopside with 8.9 microns dispersion - up to 45.8%. It was found that the greater the dispersion of inert mineral additive is, the less its optimum amount providing maximum hardening of fine-grained concrete is. Thus, the optimum ratio of these two mineral additives was determined to achieve the required strength. Adding 12% of silica fume and 7% of diopside with 52.5 microns dispersion provides the highest efficiency of the concrete strength properties. The fine concrete with such relation of additives has the strength 2.5 times greater compared to the control one.

  10. Structure in defocused beams of x-ray mirrors: causes and possible solutions

    Science.gov (United States)

    Sutter, John P.; Alcock, Simon G.; Rust, Fiona; Wang, Hongchang; Sawhney, Kawal

    2014-09-01

    Grazing incidence mirrors are now a standard optic for focusing X-ray beams. Both bimorph and mechanically bendable mirrors are widely used at Diamond Light Source because they permit a wide choice of focal lengths. They can also be deliberately set out of focus to enlarge the X-ray beam, and indeed many beamline teams now wish to generate uniform beam spots of variable size. However, progress has been slowed by the appearance of fine structure in these defocused beams. Measurements showing the relationship between the medium-frequency polishing error and this structure over a variety of beam sizes will be presented. A theoretical model for the simulations of defocused beams from general mirrors will then be developed. Not only the figure error and its first derivative the slope error, but also the second derivative, the curvature error, must be considered. In conclusion, possible ways to reduce the defocused beam structure by varying the actuators' configuration and settings will be discussed.

  11. Coherent beam-beam effects

    International Nuclear Information System (INIS)

    Chao, A.W.

    1992-01-01

    There are two physical pictures that describe the beam-beam interaction in a storage ring collider: The weak-strong and the strong-strong pictures. Both pictures play a role in determining the beam-beam behavior. This review addresses only the strong-strong picture. The corresponding beam dynamical effects are referred to as the coherent beam-beam effects. Some basic knowledge of the weak-strong picture is assumed. To be specific, two beams of opposite charges are considered. (orig.)

  12. Dutch Alternatives to Imprisonment and Fines

    NARCIS (Netherlands)

    Peters, Laura; Hilgendorf, Eric; Valerius, Brian

    2015-01-01

    The modern Dutch sanctioning system started to develop as from 1886 with the introduction of the Wetboek van Strafrecht (Dutch Penal Code). With its primary focus on imprisonment and fines, this Code only included three principal penalties. However, it has undergone a statutory evolution, both in

  13. Top-down, in-plane GaAs nanowire MOSFETs on an Al2O3 buffer with a trigate oxide from focused ion-beam milling and chemical oxidation

    Science.gov (United States)

    Lee, S. C.; Neumann, A.; Jiang, Y.-B.; Artyushkova, K.; Brueck, S. R. J.

    2016-09-01

    The top-down fabrication of an in-plane nanowire (NW) GaAs metal-oxide-semiconductor field-effect transistor (MOSFET) with a trigate oxide implemented by liquid-phase chemical-enhanced oxidation (LPCEO) is reported. A 2 μm long channel having an effective cross section ˜70 × 220 nm2 is directly fabricated into an epitaxial n +-GaAs layer. This in-plane NW structure is achieved by focused ion beam (FIB) milling and hydrolyzation oxidation resulting in electronic isolation from the substrate through a semiconductor-on-insulator structure with an n +-GaAs/Al2O3 layer stack. The channel is epitaxially connected to the μm-scale source and drain within a single layer for a planar MOSFET to avoid any issues of ohmic contact and LPCEO to the NW. To fabricate a MOSFET, the top and the two sidewalls of the in-plane NW are oxidized by LPCEO to relieve the surface damage from FIB as well as to transform these surfaces to a ˜15 nm thick gate oxide. This trigate device has threshold voltage ˜0.14 V and peak transconductance ˜35 μS μm-1 with a subthreshold swing ˜150 mV/decade and on/off ratio of drain current ˜103, comparable to the performance of bottom-up NW devices.

  14. Survey of beam-beam limitations

    International Nuclear Information System (INIS)

    Courant, E.; Cornacchia, M.; Donald, M.M.R.; Evans, L.R.; Tazzari, S.; Wilson, E.J.N.

    1979-01-01

    The effect of beam-beam interaction is known to limit the luminosity of electron-positron storage rings and will, no doubt, limit the proton-antiproton collision scheme for the SPS. While theorists are struggling to explain this phenomenon it is more instructive to list their failures than their rather limited successes, in the hope that experiments may emerge which will direct their endeavors. The search for a description of a nonlinear system as it approaches the limit in which ordered motion breaks down, is the nub of the problem. It has engaged many fine mathematical intellects for decades and will no doubt continue to do so long after ISABELLE, the p antip and LEP are past achievements. Empirical scaling laws are emerging which relate electron machines to each other but their extrapolation to proton machines remain a very speculative exercise. Experimental data on proton limits is confined to one machine, the ISR, which does not normally suffer the beam-beam effect and where it must be artificially induced or simulated. This machine is also very different in important ways from the p antip collider. The gloomy picture which has emerged recently is that the fixed limits which were conventionally assumed for proton and electron machines can only be said to be valid for the machines which engendered them - the best guess that could be made at the time. They are very difficult to extrapolate to other sets of parameters

  15. Beam Transport Testing for the Production Accelerator Arrangement

    Energy Technology Data Exchange (ETDEWEB)

    Gromov, R. [Argonne National Lab. (ANL), Argonne, IL (United States); Chemerisov, S. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2014-02-14

    The beam transport system is designed to deliver an electron beam from the accelerator to the target. The design of the beam line depends on beam parameter (energy, energy spread, etc.) and target geometry. Elements of the beam transport system should provide transportation, focusing, and positioning of the beam onto the target surface.

  16. Imeilus Fine 5

    Index Scriptorium Estoniae

    2017-01-01

    Vaba Lava teatrikeskuse laval esineb Fine 5 oma lavastusega "Imeilus". Tiina Ollesk ja Renee Nõmmik, tantsulavastuse autorid on koreograafid, õppejõud, lavastajad ja kogemustega tantsijad. 29. jaanuaril korraldavad Tiina Ollesk ja Renee Nõmmik Tallinna Ülikoolis kaasaegse liikumismõtlemise töötoa, mis on pühendatud lavastusele "Imeilus"

  17. The Fine Dutch Tradition

    NARCIS (Netherlands)

    Hooimeijer, F.L.

    2012-01-01

    Publication of the exhibition and symposium on water adaptive urban planning and architecture in Bangkok. The Urban Fine Dutch Tradition is a dynamic tradition of making urban designs using the parameters of the natural system – incorperating in an efficient way the hydrological cycle, the soil and

  18. Transport of reservoir fines

    DEFF Research Database (Denmark)

    Yuan, Hao; Shapiro, Alexander; Stenby, Erling Halfdan

    Modeling transport of reservoir fines is of great importance for evaluating the damage of production wells and infectivity decline. The conventional methodology accounts for neither the formation heterogeneity around the wells nor the reservoir fines’ heterogeneity. We have developed an integral...

  19. A fine art

    Energy Technology Data Exchange (ETDEWEB)

    Schnabel, G.; Raaff, T. [Andritz AG (Austria)

    2006-07-15

    The paper describes a new dewatering system for coal fines which challenges established processes by using screenbowl centrifuge and hyperbaric filter combinations. Company acquisitions over the past three to four years enabled Andritz AG to develop a new system combining two technologies. The article describes the benefits of the combination process and explains the basic operation of these machines. 4 figs.

  20. Fine 5 lavastab Venemaal

    Index Scriptorium Estoniae

    2013-01-01

    Tantsuteatru Fine 5 koreograafid Tiina Ollesk ja Rene Nõmmik toovad Jekaterinburgis välja lavastuse "... and Red", esitajaks Venemaa nimekas nüüdistantsutrupp Provintsialnõje Tantsõ. Lavastuses kõlab Taavo Remmeli kontrabassiimprovisatsioon "12.12.2006"