Beam Pattern Analysis of the Plate-type Waveguide Sensor for Under-Sodium Viewing

International Nuclear Information System (INIS)

Kim, Hoewoong; Joo, Youngsang; Park, Changgyu; Kim, Jongbum

2013-01-01

Sensor for under-sodium viewing (USV) in a sodium-cooled fast reactor (SFR) has been developed. In the developed WG sensor approach, the A0 mode Lamb wave is used and a thin beryllium layer is coated on the waveguide surface to improve the ultrasonic radiation ability in a sodium environment. In this work, the beam pattern radiated from the developed plate-type WG sensor is investigated analytically to understand and predict the ultrasonic beam radiation property of the WG sensor in a liquid. Analytic calculations to obtain beam patterns for two kinds of WG sensors with and without beryllium coating layers were carried out and the results were compared with those obtained by experiments. In this work, the beam pattern of the plate-type WG sensor for USV was investigated analytically. Employing the far-field approximation, the acoustic response at a given measurement position was calculated for the plate-type WG sensors with and without beryllium coating layers. The beam patterns of WG sensors were predicted by the analytic calculation and the corresponding experiments were carried out. The results showed that the far-field beam pattern radiated from the plate-type WG sensor could be well predicted by an analytic calculation. The radiation beam angles obtained by the analytical calculation were in good agreement with those obtained by experiments

Effects of source and receiver locations in predicting room transfer functions by a phased beam tracing method

DEFF Research Database (Denmark)

Jeong, Cheol-Ho; Ih, Jeong-Guon

2012-01-01

The accuracy of a phased beam tracing method in predicting transfer functions is investigated with a special focus on the positions of the source and receiver. Simulated transfer functions for various source-receiver pairs using the phased beam tracing method were compared with analytical Green’s...

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

A low cost high resolution pattern generator for electron-beam lithography

International Nuclear Information System (INIS)

Pennelli, G.; D'Angelo, F.; Piotto, M.; Barillaro, G.; Pellegrini, B.

2003-01-01

A simple, very low cost pattern generator for electron-beam lithography is presented. When it is applied to a scanning electron microscope, the system allows a high precision positioning of the beam for lithography of very small structures. Patterns are generated by a suitable software implemented on a personal computer, by using very simple functions, allowing an easy development of new writing strategies for a great adaptability to different user necessities. Hardware solutions, as optocouplers and battery supply, have been implemented for reduction of noise and disturbs on the voltages controlling the positioning of the beam

Reference Beam Pattern Design for Frequency Invariant Beamforming Based on Fast Fourier Transform

Directory of Open Access Journals (Sweden)

Wang Zhang

2016-09-01

Full Text Available In the field of fast Fourier transform (FFT-based frequency invariant beamforming (FIB, there is still an unsolved problem. That is the selection of the reference beam to make the designed wideband pattern frequency invariant (FI over a given frequency range. This problem is studied in this paper. The research shows that for a given array, the selection of the reference beam pattern is determined by the number of sensors and the ratio of the highest frequency to the lowest frequency of the signal (RHL. The length of the weight vector corresponding to a given reference beam pattern depends on the reference frequency. In addition, the upper bound of the weight length to ensure the FI property over the whole frequency band of interest is also given. When the constraints are added to the reference beam, it does not affect the FI property of the designed wideband beam as long as the symmetry of the reference beam is ensured. Based on this conclusion, a scheme for reference beam design is proposed.

Synthesis of Steered Flat-top Beam Pattern Using Evolutionary Algorithm

Directory of Open Access Journals (Sweden)

D. Mandal

2016-12-01

Full Text Available In this paper a pattern synthesis method based on Evolutionary Algorithm is presented. A Flat-top beam pattern has been generated from a concentric ring array of isotropic elements by finding out the optimum set of elements amplitudes and phases using Differential Evolution algorithm. The said pattern is generated in three predefined azimuth planes instate of a single phi plane and also verified for a range of azimuth plane for the same optimum excitations. The main beam is steered to an elevation angle of 30 degree with lower peak SLL and ripple. Dynamic range ratio (DRR is also being improved by eliminating the weakly excited array elements, which simplify the design complexity of feed networks.

Direct generation of abruptly focusing vortex beams using a 3/2 radial phase-only pattern.

Science.gov (United States)

Davis, Jeffrey A; Cottrell, Don M; Zinn, Jonathan M

2013-03-20

Abruptly focusing Airy beams have previously been generated using a radial cubic phase pattern that represents the Fourier transform of the Airy beam. The Fourier transform of this pattern is formed using a system length of 2f, where f is the focal length of the Fourier transform lens. In this work, we directly generate these abruptly focusing Airy beams using a 3/2 radial phase pattern encoded onto a liquid crystal display. The resulting optical system is much shorter. In addition, we can easily produce vortex patterns at the focal point of these beams. Experimental results match theoretical predictions.

Pattern transfer on fused silica samples using sub-aperture reactive ion beam etching

Energy Technology Data Exchange (ETDEWEB)

Miessler, Andre; Arnold, Thomas [Leibniz-Institut fuer Oberflaechenmodifizierung (IOM), Permoserstrasse 15, D-04318 Leipzig (Germany)

2012-07-01

In comparison to sole Ar ion beam sputtering Reactive Ion Beam Etching (RIBE) reveals the main advantage of increasing the selectivity for different kind of materials due to chemical contributions during the material removal. Therefore RIBE is qualified to be an excellent candidate for pattern transfer applications. The goal of the present study is to apply a sub-aperture reactive ion beam for pattern transfer on large fused silica samples. Concerning this matter, the etching behavior in the ion beam periphery plays a decisive role. Using a Kaufman-typed ion source with NF{sub 3} as reactive gas, XPS measurements of the modified surface exposes impurities like Ni, Fe and Cr, which belongs to chemically eroded material of the plasma pot and a layer formation of silicon nitride, handicaps the etching process mainly in the beam periphery where the sputtering contribution decrease. These side effects influence the pattern transfer of trench structures, produced in AZ MIR 701 photoresist by lithography on a 2'' fused silica plate, by changing the selectivity due to modified chemical reactions of the resist layer. Concerning this we investigate a RF-Ion source for sub aperture reactive ion beam applications and finally we examine the pattern transfer on large fused silica plates using NF{sub 3}-sub-aperture RIBE.

Development of pattern aware unit (PAU) for the LCLS beam based fast feedback system

International Nuclear Information System (INIS)

Kim, K.H.; Allison, S.; Fairley, D.; Himel, T.M.; Krejcik, P.; Rogind, D.; Williams, E.

2012-01-01

LCLS is now successfully operating at its design beam repetition rate of 120 Hz, but in order to ensure stable beam operation at this high rate we have developed a new timing pattern aware EPICS controller for beam line actuators. Actuators that are capable of responding at 120 Hz are controlled by the new Pattern Aware Unit (PAU) as part of the beam-based feedback system. The beam at the LCLS is synchronized to the 60 Hz AC power line phase and is subject to electrical noise which differs according to which of the six possible AC phases is chosen from the 3-phase site power line. Beam operation at 120 Hz interleaves two of these 60 Hz phases and the feedback must be able to apply independent corrections to the beam pulse according to which of the 60 Hz timing patterns the pulse is synchronized to. The PAU works together with the LCLS Event Timing system which broadcasts a timing pattern that uniquely identifies each pulse when it is measured and allows the feedback correction to be applied to subsequent pulses belonging to the same timing pattern, or time slot, as it is referred to at SLAC. At 120 Hz operation this effectively provides us with two independent, but interleaved feedback loops. Other beam programs at the SLAC facility such as LCLS-II and FACET will be pulsed on other time slots and the PAUs in those systems will respond to their appropriate timing patterns. This paper describes the details of the PAU development: real-time requirements and achievement, scalability, and consistency. The operational results will also be described. (authors)

Inversion of convergent-beam electron diffraction patterns

International Nuclear Information System (INIS)

Bird, D.M.; Saunders, M.

1992-01-01

The problem of recovering the structure factors that contribute to a zone-axis convergent-beam diffraction pattern is discussed. It is shown that an automated matching procedure that minimizes the sum-of-squares difference between experimental and simulated patterns is effective whether one is refining accurate structure factors in a known crystal or attempting ab initio structure determination. The details of the minimization method are analysed and it is shown that a quasi-Newton method that uses analytically derived gradients is particulary effective when several structure factors are varied. The inversion method for ab initio structure determination is tested on the [110] axis of GaP, using simulated patterns as ideal 'experimental' data. (orig.)

Beam Loss Patterns at the LHC Collimators Measurements & Simulations

CERN Document Server

Böhlen, Till Tobias

2008-01-01

The Beam Loss Monitoring (BLM) system of the Large Hadron Collider (LHC) detects particle losses of circulating beams and initiates an emergency extraction of the beam in case that the BLM thresholds are exceeded. This protection is required as energy deposition in the accelerator equipment due to secondary shower particles can reach critical levels; causing damage to the beam-line components and quenches of superconducting magnets. Robust and movable beam line elements, so-called collimators, are the aperture limitations of the LHC. Consequently, they are exposed to the excess of lost beam particles and their showers. Proton loss patterns at LHC collimators have to be determined to interpret the signal of the BLM detectors and to set adequate BLM thresholds for the protection of collimators and other equipment in case of unacceptably increased loss rates. The first part of this work investigates the agreement of BLM detector measurements with simulations for an LHC-like collimation setup. The setup consists ...

Pattern transfer on large samples using a sub-aperture reactive ion beam

Energy Technology Data Exchange (ETDEWEB)

Miessler, Andre; Mill, Agnes; Gerlach, Juergen W.; Arnold, Thomas [Leibniz-Institut fuer Oberflaechenmodifizierung (IOM), Permoserstrasse 15, D-04318 Leipzig (Germany)

2011-07-01

In comparison to sole Ar ion beam sputtering Reactive Ion Beam Etching (RIBE) reveals the main advantage of increasing the selectivity for different kind of materials due to chemical contributions during the material removal. Therefore RIBE is qualified to be an excellent candidate for pattern transfer applications. The goal of the present study is to apply a sub-aperture reactive ion beam for pattern transfer on large fused silica samples. Concerning this matter, the etching behavior in the ion beam periphery plays a decisive role. Using CF{sub 4} as reactive gas, XPS measurements of the modified surface exposes impurities like Ni, Fe and Cr, which belongs to chemically eroded material of the plasma pot as well as an accumulation of carbon (up to 40 atomic percent) in the beam periphery, respectively. The substitution of CF{sub 4} by NF{sub 3} as reactive gas reveals a lot of benefits: more stable ion beam conditions in combination with a reduction of the beam size down to a diameter of 5 mm and a reduced amount of the Ni, Fe and Cr contaminations. However, a layer formation of silicon nitride handicaps the chemical contribution of the etching process. These negative side effects influence the transfer of trench structures on quartz by changing the selectivity due to altered chemical reaction of the modified resist layer. Concerning this we investigate the pattern transfer on large fused silica plates using NF{sub 3}-sub-aperture RIBE.

Demonstration of electronic pattern switching and 10x pattern demagnification in a maskless micro-ion beam reduction lithography system

International Nuclear Information System (INIS)

Ngo, V.V.; Akker, B.; Leung, K.N.; Noh, I.; Scott, K.L.; Wilde, S.

2002-01-01

A proof-of-principle ion projection lithography (IPL) system called Maskless Micro-ion beam Reduction Lithography (MMRL) has been developed and tested at the Lawrence Berkeley National Laboratory (LBNL) for future integrated circuits (ICs) manufacturing and thin film media patterning [1]. This MMRL system is aimed at completely eliminating the first stage of the conventional IPL system [2] that contains the complicated beam optics design in front of the stencil mask and the mask itself. It consists of a multicusp RF plasma generator, a multi-beamlet pattern generator, and an all-electrostatic ion optical column. Results from ion beam exposures on PMMA and Shipley UVII-HS resists using 75 keV H+ are presented in this paper. Proof-of-principle electronic pattern switching together with 10x reduction ion optics (using a pattern generator made of nine 50-(micro)m switchable apertures) has been performed and is reported in this paper. In addition, the fabrication of a micro-fabricated pattern generator [3] on an SOI membrane is also presented

Preparing patterned carbonaceous nanostructures directly by overexposure of PMMA using electron-beam lithography

Energy Technology Data Exchange (ETDEWEB)

Duan Huigao; Zhao Jianguo; Zhang Yongzhe; Xie Erqing [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Han Li [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China)], E-mail: duanhg@gmail.com, E-mail: xieeq@lzu.edu.cn

2009-04-01

The overexposure process of poly(methyl methacrylate) (PMMA) was studied in detail using electron-beam lithography. It was found that PMMA films could be directly patterned without development due to the electron-beam-induced collapse of PMMA macromolecular chains. By analyzing the evolution of surface morphologies and compositions of the overexposed PMMA films, it was also found that the transformation of PMMA from positive to negative resist was a carbonization process, so patterned carbonaceous nanostructures could be prepared directly by overexposure of PMMA using electron-beam lithography. This simple one-step process for directly obtaining patterned carbonaceous nanostructures has promising potential application as a tool to make masks and templates, nanoelectrodes, and building blocks for MEMS and nanophotonic devices.

High performance Si immersion gratings patterned with electron beam lithography

Science.gov (United States)

Gully-Santiago, Michael A.; Jaffe, Daniel T.; Brooks, Cynthia B.; Wilson, Daniel W.; Muller, Richard E.

2014-07-01

Infrared spectrographs employing silicon immersion gratings can be significantly more compact than spectro- graphs using front-surface gratings. The Si gratings can also offer continuous wavelength coverage at high spectral resolution. The grooves in Si gratings are made with semiconductor lithography techniques, to date almost entirely using contact mask photolithography. Planned near-infrared astronomical spectrographs require either finer groove pitches or higher positional accuracy than standard UV contact mask photolithography can reach. A collaboration between the University of Texas at Austin Silicon Diffractive Optics Group and the Jet Propulsion Laboratory Microdevices Laboratory has experimented with direct writing silicon immersion grating grooves with electron beam lithography. The patterning process involves depositing positive e-beam resist on 1 to 30 mm thick, 100 mm diameter monolithic crystalline silicon substrates. We then use the facility JEOL 9300FS e-beam writer at JPL to produce the linear pattern that defines the gratings. There are three key challenges to produce high-performance e-beam written silicon immersion gratings. (1) E- beam field and subfield stitching boundaries cause periodic cross-hatch structures along the grating grooves. The structures manifest themselves as spectral and spatial dimension ghosts in the diffraction limited point spread function (PSF) of the diffraction grating. In this paper, we show that the effects of e-beam field boundaries must be mitigated. We have significantly reduced ghost power with only minor increases in write time by using four or more field sizes of less than 500 μm. (2) The finite e-beam stage drift and run-out error cause large-scale structure in the wavefront error. We deal with this problem by applying a mark detection loop to check for and correct out minuscule stage drifts. We measure the level and direction of stage drift and show that mark detection reduces peak-to-valley wavefront error

Beam pattern improvement by compensating array nonuniformities in a guided wave phased array

International Nuclear Information System (INIS)

Kwon, Hyu-Sang; Lee, Seung-Seok; Kim, Jin-Yeon

2013-01-01

This paper presents a simple data processing algorithm which can improve the performance of a uniform circular array based on guided wave transducers. The algorithm, being intended to be used with the delay-and-sum beamformer, effectively eliminates the effects of nonuniformities that can significantly degrade the beam pattern. Nonuniformities can arise intrinsically from the array geometry when the circular array is transformed to a linear array for beam steering and extrinsically from unequal conditions of transducers such as element-to-element variations of sensitivity and directivity. The effects of nonuniformities are compensated by appropriately imposing weight factors on the elements in the projected linear array. Different cases are simulated, where the improvements of the beam pattern, especially the level of the highest sidelobe, are clearly seen, and related issues are discussed. An experiment is performed which uses A0 mode Lamb waves in a steel plate, to demonstrate the usefulness of the proposed method. The discrepancy between theoretical and experimental beam patterns is explained by accounting for near-field effects. (paper)

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.

Pattern evolution during ion beam sputtering; reductionistic view

Energy Technology Data Exchange (ETDEWEB)

Kim, J.-H.; Kim, J.-S., E-mail: jskim@sm.ac.kr

2016-09-15

The development of the ripple pattern during the ion beam sputtering (IBS) is expounded via the evolution of its constituent ripples. For that purpose, we perform numerical simulation of the ripple evolution that is based on Bradley–Harper model and its non-linear extension. The ripples are found to evolve via various well-defined processes such as ripening, averaging, bifurcation and their combinations, depending on their neighboring ripples. Those information on the growth kinetics of each ripple allow the detailed description of the pattern development in real space that the instability argument and the diffraction study both made in k-space cannot provide.

Problems in nonlinear acoustics: Scattering of sound by sound, parametric receiving arrays, nonlinear effects in asymmetric sound beams and pulsed finite amplitude sound beams

Science.gov (United States)

Hamilton, Mark F.

1989-08-01

Four projects are discussed in this annual summary report, all of which involve basic research in nonlinear acoustics: Scattering of Sound by Sound, a theoretical study of two nonconlinear Gaussian beams which interact to produce sum and difference frequency sound; Parametric Receiving Arrays, a theoretical study of parametric reception in a reverberant environment; Nonlinear Effects in Asymmetric Sound Beams, a numerical study of two dimensional finite amplitude sound fields; and Pulsed Finite Amplitude Sound Beams, a numerical time domain solution of the KZK equation.

IDENTIFIKASI PROFIL DASAR LAUT MENGGUNAKAN INSTRUMEN SIDE SCAN SONAR DENGAN METODE BEAM PATTERN DISCRETE-EQUI-SPACED UNSHADED LINE ARRAY

Directory of Open Access Journals (Sweden)

Muhammad Zainuddin Lubis

2017-05-01

Full Text Available Laut Punggur merupakan laut yang terletak di Batam, Kepulauan Riau yang mempunyai beragam habitat objek,dan bentuk struktur bawah laut yang memiliki dinamika laut yang sangat tinggi. Side scan sonar (SSS merupakan instrumen pengembangan sistem sonar yang mampu menunjukkan dalam gambar dua dimensional permukaan dasar laut dengan kondisi kontur, topografi, dan target secara bersamaan. Metode Beam Pattern Discrete-Equi-Spaced Unshaded Line Array digunakan untuk menghitung beam pattern dua dimensi yang tergantung pada sudut dari gelombang suara yang masuk dari sumbu array yang diterima tergantung pada sudut di mana sinar suara pada array. Penelitian ini dilakukan pada Desember 2016 di laut Punggur,Batam, Kepulauan Riau-Indonesia, dengan koordinat 104 ° 08,7102 E dan 1° 03,2448 N sampai 1 ° 03.3977 N dan 104 ° 08,8133 E, menggunakan instrumen Side Scan Sonar C-Max CM2 Tow fish dengan frekuensi 325 kHz. Hasil yang diperoleh dari perekaman terdapat 7 target, dan Beam pattern dari metode Beam Discrete-Equi-Spaced Unshaded Line Array target 4 memiliki nilai tertinggi pada directivity Pattern yaitu 21.08 dB. Hasil model beam pattern ini memiliki nilai pusat pada incidence angle (o terhadap Directivity pattern (dB tidak berada di nilai 0 ataupun pada pusat beam pattern yang dihasilkan pada target 6 dengan nilai incident angle -1.5 o dan 1.5o mengalami penurunan hingga -40 dB. Karakteristik sedimen dasar perairan di laut punggur ditemukan lebih banyak pasir. Hasil metode Beam Discrete-Equi-Spaced Unshaded Line Array ditemukan bangkai kapal tenggelam.Kata Kunci: Side Scan Sonar, Beam Pattern Discrete-Equi-Spaced Unshaded Line Array, Incidence angle, Directivity pattern IDENTIFICATION OF SEABED PROFILE USING SIDE SCAN SONAR INSTRUMENT WITH PATTERN DISCRETE-EQUI-SPACED UNSHADED LINE ARRAY METHODRiau Islands is an island that has a variety of habitat objects, and forms of submarine structures that have a very high ocean dynamics, Punggur Sea is the sea

Germanium growth on electron beam lithography patterned Si3N4/Si(001) substrate using molecular beam epitaxy

Science.gov (United States)

Sarkar, Subhendu Sinha; Katiyar, Ajit K.; Sarkar, Arijit; Dhar, Achintya; Rudra, Arun; Khatri, Ravinder K.; Ray, Samit Kumar

2018-04-01

It is important to investigate the growth dynamics of Ge adatoms under different surface stress regimes of the patterned dielectric to control the selective growth of self-assembled Ge nanostructures on silicon. In the present work, we have studied the growth of Ge by molecular beam epitaxy on nanometer scale patterned Si3N4/Si(001) substrates generated using electron beam lithography. The pitch of the patterns has been varied to investigate its effect on the growth of Ge in comparison to un-patterned Si3N4. For the patterned Si3N4 film, Ge did not desorbed completely from the Si3N4 film and hence no site selective growth pattern is observed. Instead, depending upon the pitch, Ge growth has occurred in different growth modes around the openings in the Si3N4. For the un-patterned substrate, the morphology exhibits the occurrence of uniform 3D clustering of Ge adatoms on Si3N4 film. This variation in the growth modes of Ge is attributed to the variation of residual stress in the Si3N4 film for different pitch of holes, which has been confirmed theoretically through Comsol Multiphysics simulation. The variation in stress for different pitches resulted in modulation of surface energy of the Si3N4 film leading to the different growth modes of Ge.

External Beam Radiotherapy for Colon Cancer: Patterns of Care

International Nuclear Information System (INIS)

Dunn, Emily F.; Kozak, Kevin R.; Moody, John S.

2010-01-01

Purpose: Despite its common and well characterized use in other gastrointestinal malignancies, little is known about radiotherapy (RT) use in nonmetastatic colon cancer in the United States. To address the paucity of data regarding RT use in colon cancer management, we examined the RT patterns of care in this patient population. Methods and Materials: Patients with nonmetastatic colon cancer, diagnosed between 1988 and 2005, were identified in the Surveillance, Epidemiology, and End Results (SEER) database. Univariate and multivariate methods were used to identify factors associated with RT use. Results: On univariate analysis, tumor location, age, sex, race, T stage, N stage, and geographic location were each associated with differences in RT use (all p < 0.01). In general, younger patients, male patients, and patients with more advanced disease were more likely to receive RT. On multivariate analysis, tumor location, age, gender, T and N stage, time of diagnosis and geographic location were significantly associated with RT use (all p < 0.001). Race, however, was not associated with RT use. On multivariate analysis, patients diagnosed in 1988 were 2.5 times more likely to receive RT than those diagnosed in 2005 (p = 0.001). Temporal changes in RT use reflect a responsiveness to evolving evidence related to the therapeutic benefits of adjuvant RT. Conclusions: External beam RT is infrequently used for colon cancer, and its use varies according to patient and tumor characteristics. RT use has declined markedly since the late 1980s; however, it continues to be used for nonmetastatic disease in a highly individualized manner.

Localized conductive patterning via focused electron beam reduction of graphene oxide

Energy Technology Data Exchange (ETDEWEB)

Kim, Songkil; Henry, Mathias [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Kulkarni, Dhaval D.; Zackowski, Paul; Jang, Seung Soon; Tsukruk, Vladimir V. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Fedorov, Andrei G., E-mail: agf@gatech.edu [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

2015-03-30

We report on a method for “direct-write” conductive patterning via reduction of graphene oxide (GO) sheets using focused electron beam induced deposition (FEBID) of carbon. FEBID treatment of the intrinsically dielectric graphene oxide between two metal terminals opens up the conduction channel, thus enabling a unique capability for nanoscale conductive domain patterning in GO. An increase in FEBID electron dose results in a significant increase of the domain electrical conductivity with improving linearity of drain-source current vs. voltage dependence, indicative of a change of graphene oxide electronic properties from insulating to semiconducting. Density functional theory calculations suggest a possible mechanism underlying this experimentally observed phenomenon, as localized reduction of graphene oxide layers via interactions with highly reactive intermediates of electron-beam-assisted dissociation of surface-adsorbed hydrocarbon molecules. These findings establish an unusual route for using FEBID as nanoscale lithography and patterning technique for engineering carbon-based nanomaterials and devices with locally tailored electronic properties.

Pattern formation on Ge by low energy ion beam erosion

International Nuclear Information System (INIS)

Teichmann, Marc; Lorbeer, Jan; Frost, Frank; Rauschenbach, Bernd; Ziberi, Bashkim

2013-01-01

Modification of nanoscale surface topography is inherent to low-energy ion beam erosion processes and is one of the most important fields of nanotechnology. In this report a comprehensive study of surface smoothing and self-organized pattern formation on Ge(100) by using different noble gases ion beam erosion is presented. The investigations focus on low ion energies (⩽ 2000 eV) and include the entire range of ion incidence angles. It is found that for ions (Ne, Ar) with masses lower than the mass of the Ge target atoms, no pattern formation occurs and surface smoothing is observed for all angles of ion incidence. In contrast, for erosion with higher mass ions (Kr, Xe), ripple formation starts at incidence angles of about 65° depending on ion energy. At smaller incident angles surface smoothing occurs again. Investigations of the surface dynamics for specific ion incidence angles by changing the ion fluence over two orders of magnitude gives a clear evidence for coarsening and faceting of the surface pattern. Both observations indicate that gradient-dependent sputtering and reflection of primary ions play crucial role in the pattern evolution, just at the lowest accessible fluences. The results are discussed in relation to recently proposed redistributive or stress-induced models for pattern formation. In addition, it is argued that a large angular variation of the sputter yield and reflected primary ions can significantly contribute to pattern formation and evolution as nonlinear and non-local processes as supported by simulation of sputtering and ion reflection. (paper)

Disclosure Pattern among People Living with HIV-AIDS Receiving ...

African Journals Online (AJOL)

Background Disclosure of HIV status has been described as a preventive strategy in the transmission of HIV among sexual partners as well as a necessary step for PLWHA to receive necessary support from family members and the community. The study was undertaken to determine the pattern and rates of disclosure ...

Statistical spatial properties of speckle patterns generated by multiple laser beams

International Nuclear Information System (INIS)

Le Cain, A.; Sajer, J. M.; Riazuelo, G.

2011-01-01

This paper investigates hot spot characteristics generated by the superposition of multiple laser beams. First, properties of speckle statistics are studied in the context of only one laser beam by computing the autocorrelation function. The case of multiple laser beams is then considered. In certain conditions, it is shown that speckles have an ellipsoidal shape. Analytical expressions of hot spot radii generated by multiple laser beams are derived and compared to numerical estimates made from the autocorrelation function. They are also compared to numerical simulations performed within the paraxial approximation. Excellent agreement is found for the speckle width as well as for the speckle length. Application to the speckle patterns generated in the Laser MegaJoule configuration in the zone where all the beams overlap is presented. Influence of polarization on the size of the speckles as well as on their abundance is studied.

External beam radiation for retinoblastoma: Results, patterns of failure, and a proposal for treatment guidelines

International Nuclear Information System (INIS)

Hernandez, J. Carlos; Brady, Luther W.; Shields, Jerry A.; Shields, Carol L.; Potter, Patrick de; Karlsson, Ulf L.; Markoe, Arnold M.; Amendola, Beatriz E.; Singh, Arun

1996-01-01

Purpose: To analyze treatment results and patterns of failure following external beam radiation for retinoblastoma and propose treatment guidelines according to specific clinical variables. Methods and Materials: We analyzed 27 patients (34 eyes) with retinoblastoma who received external beam radiation as initial treatment at Hahnemann University Hospital from October 1980 to December 1991 and have been followed for at least 1 year. Of the 34 eyes, 14 were Groups I-II (Reese-Ellsworth classification), 7 were Group III, and 13 were Groups IV-V. Doses ranged from 34.5-49.5 Gy (mean 44.3 Gy, median 45 Gy) in 1.5-2.0 Gy fractions generally delivered through anterior and lateral wedged pair fields. Results: At a mean follow up of 35.2 months (range 12-93 months), local tumor control was obtained in 44% (15 out of 34) of eyes with external beam radiation alone. Salvage therapy (plaque brachytherapy, cryotherapy, and/or photocoagulation) controlled an additional 10 eyes (29.5%), so that overall ocular survival has been 73.5%. Local tumor control with external beam radiotherapy alone was obtained in 78.5% (11 out of 14) of eyes in Groups I-II, but in only 20% (4 out of 20) of eyes in Groups III-V. A total of 67 existing tumors were identified prior to treatment in the 34 treated eyes and local control with external beam radiation alone was obtained in 87% (46 out of 53) of tumors measuring 15 mm or less and in 50% (7 out of 14) of tumors measuring more than 15 mm. When analyzing patterns of failure in the 19 eyes that relapsed, a total of 28 failure sites were identified and consisted of progression of vitreous seeds in seven instances (25% of failure sites) recurrences from previously existing tumors in 10 instances (36% of failure sites) and development of new tumors in previously uninvolved retina in 11 instances (39% of failure sites). Conclusions: 1) We find that external beam radiation to a dose of 45 Gy in fractions of 1.5 to 2.0 Gy provides adequate tumor control

Interference pattern period measurement at picometer level

Science.gov (United States)

Xiang, Xiansong; Wei, Chunlong; Jia, Wei; Zhou, Changhe; Li, Minkang; Lu, Yancong

2016-10-01

To produce large scale gratings by Scanning Beam Interference Lithography (SBIL), a light spot containing grating pattern is generated by two beams interfering, and a scanning stage is used to drive the substrate moving under the light spot. In order to locate the stage at the proper exposure positions, the period of the Interference pattern must be measured accurately. We developed a set of process to obtain the period value of two interfering beams at picometer level. The process includes data acquisition and data analysis. The data is received from a photodiode and a laser interferometer with sub-nanometer resolution. Data analysis differs from conventional analyzing methods like counting wave peaks or using Fourier transform to get the signal period, after a preprocess of filtering and envelope removing, the mean square error is calculated between the received signal and ideal sinusoid waves to find the best-fit frequency, thus an accuracy period value is acquired, this method has a low sensitivity to amplitude noise and a high resolution of frequency. With 405nm laser beams interfering, a pattern period value around 562nm is acquired by employing this process, fitting diagram of the result shows the accuracy of the period value reaches picometer level, which is much higher than the results of conventional methods.

Influence of laser beam profiles on received power fluctuation

Science.gov (United States)

Dordova, Lucie; Diblik, Jan

2011-09-01

Gaussian beam is very often used for the transmission of information in optical wireless links. The usage of this optical beam has its advantages and, of course, disadvantages. This work focuses on possibilities of using laser beams with different distribution of optical intensity - Top Hat beam. Creation of the optical beam with selected optical intensity profile will be briefly described. Optical beams will propagate through the "clear" and stationary atmosphere in the experimental part of this work. These results will be compared with the data obtained after a laser beam is passed through the turbulent and attenuated atmosphere. We will use an ultrasound fog generator for laser beam attenuation testing. To create the turbulence, infra radiators will be applied. Particular results obtained from different atmospheric conditions will be compared and using different types of optical beams will be assessed.

Diffractive elements for generating microscale laser beam patterns: a Y2K problem

Science.gov (United States)

Teiwes, Stephan; Krueger, Sven; Wernicke, Guenther K.; Ferstl, Margit

2000-03-01

Lasers are widely used in industrial fabrication for engraving, cutting and many other purposes. However, material processing at very small scales is still a matter of concern. Advances in diffractive optics could provide for laser systems that could be used for engraving or cutting of micro-scale patterns at high speeds. In our paper we focus on the design of diffractive elements which can be used for this special application. It is a common desire in material processing to apply 'discrete' as well as 'continuous' beam patterns. Especially, the latter case is difficult to handle as typical micro-scale patterns are characterized by bad band-limitation properties, and as speckles can easily occur in beam patterns. It is shown in this paper that a standard iterative design method usually fails to obtain diffractive elements that generate diffraction patterns with acceptable quality. Insights gained from an analysis of the design problems are used to optimize the iterative design method. We demonstrate applicability and success of our approach by the design of diffractive phase elements that generate a discrete and a continuous 'Y2K' pattern.

Microcomb-Based True-Time-Delay Network for Microwave Beamforming With Arbitrary Beam Pattern Control

Science.gov (United States)

Xue, Xiaoxiao; Xuan, Yi; Bao, Chengying; Li, Shangyuan; Zheng, Xiaoping; Zhou, Bingkun; Qi, Minghao; Weiner, Andrew M.

2018-06-01

Microwave phased array antennas (PAAs) are very attractive to defense applications and high-speed wireless communications for their abilities of fast beam scanning and complex beam pattern control. However, traditional PAAs based on phase shifters suffer from the beam-squint problem and have limited bandwidths. True-time-delay (TTD) beamforming based on low-loss photonic delay lines can solve this problem. But it is still quite challenging to build large-scale photonic TTD beamformers due to their high hardware complexity. In this paper, we demonstrate a photonic TTD beamforming network based on a miniature microresonator frequency comb (microcomb) source and dispersive time delay. A method incorporating optical phase modulation and programmable spectral shaping is proposed for positive and negative apodization weighting to achieve arbitrary microwave beam pattern control. The experimentally demonstrated TTD beamforming network can support a PAA with 21 elements. The microwave frequency range is $\\mathbf{8\\sim20\\ {GHz}}$, and the beam scanning range is $\\mathbf{\\pm 60.2^\\circ}$. Detailed measurements of the microwave amplitudes and phases are performed. The beamforming performances of Gaussian, rectangular beams and beam notch steering are evaluated through simulations by assuming a uniform radiating antenna array. The scheme can potentially support larger PAAs with hundreds of elements by increasing the number of comb lines with broadband microcomb generation.

Direct nano-patterning of graphene with helium ion beams

International Nuclear Information System (INIS)

Naitou, Y.; Iijima, T.; Ogawa, S.

2015-01-01

Helium ion microscopy (HIM) was used for direct nano-patterning of single-layer graphene (SLG) on SiO 2 /Si substrates. This technique involves irradiation of the sample with accelerated helium ions (He + ). Doses of 2.0 × 10 16  He +  cm −2 from a 30 kV beam induced a metal-insulator transition in the SLG. The resolution of HIM patterning on SLG was investigated by fabricating nanoribbons and nanostructures. Analysis of scanning capacitance microscopy measurements revealed that the spatial resolution of HIM patterning depended on the dosage of He + in a non-monotonic fashion. Increasing the dose from 2.0 × 10 16 to 5.0 × 10 16  He +  cm −2 improved the spatial resolution to several tens of nanometers. However, doses greater than 1.0 × 10 17  He +  cm −2 degraded the patterning characteristics. Direct patterning using HIM is a versatile approach to graphene fabrication and can be applied to graphene-based devices

In vivo visualization method by absolute blood flow velocity based on speckle and fringe pattern using two-beam multipoint laser Doppler velocimetry

Energy Technology Data Exchange (ETDEWEB)

Kyoden, Tomoaki, E-mail: kyouden@nc-toyama.ac.jp; Naruki, Shoji; Akiguchi, Shunsuke; Momose, Noboru; Homae, Tomotaka; Hachiga, Tadashi [National Institute of Technology, Toyama College, 1-2 Ebie-Neriya, Imizu, Toyama 933-0293 (Japan); Ishida, Hiroki [Department of Applied Physics, Faculty of Science, Okayama University of Science, 1-1 Ridai-cho, Okayama 700-0005 (Japan); Andoh, Tsugunobu [Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194 (Japan); Takada, Yogo [Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi, Osaka 558-8585 (Japan)

2016-08-28

Two-beam multipoint laser Doppler velocimetry (two-beam MLDV) is a non-invasive imaging technique able to provide an image of two-dimensional blood flow and has potential for observing cancer as previously demonstrated in a mouse model. In two-beam MLDV, the blood flow velocity can be estimated from red blood cells passing through a fringe pattern generated in the skin. The fringe pattern is created at the intersection of two beams in conventional LDV and two-beam MLDV. Being able to choose the depth position is an advantage of two-beam MLDV, and the position of a blood vessel can be identified in a three-dimensional space using this technique. Initially, we observed the fringe pattern in the skin, and the undeveloped or developed speckle pattern generated in a deeper position of the skin. The validity of the absolute velocity value detected by two-beam MLDV was verified while changing the number of layers of skin around a transparent flow channel. The absolute velocity value independent of direction was detected using the developed speckle pattern, which is created by the skin construct and two beams in the flow channel. Finally, we showed the relationship between the signal intensity and the fringe pattern, undeveloped speckle, or developed speckle pattern based on the skin depth. The Doppler signals were not detected at deeper positions in the skin, which qualitatively indicates the depth limit for two-beam MLDV.

High-damage-threshold static laser beam shaping using optically patterned liquid-crystal devices.

Science.gov (United States)

Dorrer, C; Wei, S K-H; Leung, P; Vargas, M; Wegman, K; Boulé, J; Zhao, Z; Marshall, K L; Chen, S H

2011-10-15

Beam shaping of coherent laser beams is demonstrated using liquid crystal (LC) cells with optically patterned pixels. The twist angle of a nematic LC is locally set to either 0 or 90° by an alignment layer prepared via exposure to polarized UV light. The two distinct pixel types induce either no polarization rotation or a 90° polarization rotation, respectively, on a linearly polarized optical field. An LC device placed between polarizers functions as a binary transmission beam shaper with a highly improved damage threshold compared to metal beam shapers. Using a coumarin-based photoalignment layer, various devices have been fabricated and tested, with a measured single-shot nanosecond damage threshold higher than 30 J/cm2.

Simulating discrete models of pattern formation by ion beam sputtering

International Nuclear Information System (INIS)

Hartmann, Alexander K; Kree, Reiner; Yasseri, Taha

2009-01-01

A class of simple, (2+1)-dimensional, discrete models is reviewed, which allow us to study the evolution of surface patterns on solid substrates during ion beam sputtering (IBS). The models are based on the same assumptions about the erosion process as the existing continuum theories. Several distinct physical mechanisms of surface diffusion are added, which allow us to study the interplay of erosion-driven and diffusion-driven pattern formation. We present results from our own work on evolution scenarios of ripple patterns, especially for longer timescales, where nonlinear effects become important. Furthermore we review kinetic phase diagrams, both with and without sample rotation, which depict the systematic dependence of surface patterns on the shape of energy depositing collision cascades after ion impact. Finally, we discuss some results from more recent work on surface diffusion with Ehrlich-Schwoebel barriers as the driving force for pattern formation during IBS and on Monte Carlo simulations of IBS with codeposition of surfactant atoms.

Simulation of 3-D radiation beam patterns propagated through a planar interface from ultrasonic phased array transducers.

Science.gov (United States)

Song, Sung-Jin; Kim, Chang-Hwan

2002-05-01

Phased array transducers are quite often mounted on solid wedges with specific angles in many practical ultrasonic inspections of thin plates phased array techniques with testing set-up, it is essential to have thorough understanding on the characteristics of radiation beam pattern produced in the interrogated medium. To address such a need, this paper proposes a systematic way to calculate full 3-D radiation beam patterns produced in the interrogated solid medium by phased array transducers mounted on a solid wedge. In order to investigate the characteristics of radiation beam patterns in steel, simulation is carried out for 7.5 MHz array transducers mounted on an acrylic wedge with the angle of 15.45 degrees with various of steering angles and/or focal planes.

Direct nano-patterning of graphene with helium ion beams

Energy Technology Data Exchange (ETDEWEB)

Naitou, Y., E-mail: yu-naitou@aist.go.jp [Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8562 (Japan); Iijima, T.; Ogawa, S. [Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba 305-8569 (Japan)

2015-01-19

Helium ion microscopy (HIM) was used for direct nano-patterning of single-layer graphene (SLG) on SiO{sub 2}/Si substrates. This technique involves irradiation of the sample with accelerated helium ions (He{sup +}). Doses of 2.0 × 10{sup 16 }He{sup + }cm{sup −2} from a 30 kV beam induced a metal-insulator transition in the SLG. The resolution of HIM patterning on SLG was investigated by fabricating nanoribbons and nanostructures. Analysis of scanning capacitance microscopy measurements revealed that the spatial resolution of HIM patterning depended on the dosage of He{sup +} in a non-monotonic fashion. Increasing the dose from 2.0 × 10{sup 16} to 5.0 × 10{sup 16 }He{sup + }cm{sup −2} improved the spatial resolution to several tens of nanometers. However, doses greater than 1.0 × 10{sup 17 }He{sup + }cm{sup −2} degraded the patterning characteristics. Direct patterning using HIM is a versatile approach to graphene fabrication and can be applied to graphene-based devices.

Crossover patterning by the beam-film model: analysis and implications.

Directory of Open Access Journals (Sweden)

Liangran Zhang

2014-01-01

Full Text Available Crossing-over is a central feature of meiosis. Meiotic crossover (CO sites are spatially patterned along chromosomes. CO-designation at one position disfavors subsequent CO-designation(s nearby, as described by the classical phenomenon of CO interference. If multiple designations occur, COs tend to be evenly spaced. We have previously proposed a mechanical model by which CO patterning could occur. The central feature of a mechanical mechanism is that communication along the chromosomes, as required for CO interference, can occur by redistribution of mechanical stress. Here we further explore the nature of the beam-film model, its ability to quantitatively explain CO patterns in detail in several organisms, and its implications for three important patterning-related phenomena: CO homeostasis, the fact that the level of zero-CO bivalents can be low (the "obligatory CO", and the occurrence of non-interfering COs. Relationships to other models are discussed.

Three-dimensional patterning in polymer optical waveguides using focused ion beam milling

Science.gov (United States)

Kruse, Kevin; Burrell, Derek; Middlebrook, Christopher

2016-07-01

Waveguide (WG) photonic-bridge taper modules are designed for symmetric planar coupling between silicon WGs and single-mode fibers (SMFs) to minimize photonic chip and packaging footprint requirements with improving broadband functionality. Micromachined fabrication and evaluation of polymer WG tapers utilizing high-resolution focused ion beam (FIB) milling is performed and presented. Polymer etch rates utilizing the FIB and optimal methods for milling polymer tapers are identified for three-dimensional patterning. Polymer WG tapers with low sidewall roughness are manufactured utilizing FIB milling and optically tested for fabrication loss. FIB platforms utilize a focused beam of ions (Ga+) to etch submicron patterns into substrates. Fabricating low-loss polymer WG taper prototypes with the FIB before moving on to mass-production techniques provides theoretical understanding of the polymer taper and its feasibility for connectorization devices between silicon WGs and SMFs.

High quality single shot diffraction patterns using ultrashort megaelectron volt electron beams from a radio frequency photoinjector

Energy Technology Data Exchange (ETDEWEB)

Musumeci, P.; Moody, J. T.; Scoby, C. M.; Gutierrez, M. S. [Department of Physics and Astronomy, UCLA, Los Angeles, California 90095 (United States); Bender, H. A.; Wilcox, N. S. [National Security Technologies, LLC, Los Alamos Operations, Los Alamos, New Mexico 87544 (United States)

2010-01-15

Single shot diffraction patterns using a 250-fs-long electron beam have been obtained at the UCLA Pegasus laboratory. High quality images with spatial resolution sufficient to distinguish closely spaced peaks in the Debye-Scherrer ring pattern have been recorded by scattering the 1.6 pC 3.5 MeV electron beam generated in the rf photoinjector off a 100-nm-thick Au foil. Dark current and high emittance particles are removed from the beam before sending it onto the diffraction target using a 1 mm diameter collimating hole. These results open the door to the study of irreversible phase transformations by single shot MeV electron diffraction.

High quality single shot diffraction patterns using ultrashort megaelectron volt electron beams from a radio frequency photoinjector.

Science.gov (United States)

Musumeci, P; Moody, J T; Scoby, C M; Gutierrez, M S; Bender, H A; Wilcox, N S

2010-01-01

Single shot diffraction patterns using a 250-fs-long electron beam have been obtained at the UCLA Pegasus laboratory. High quality images with spatial resolution sufficient to distinguish closely spaced peaks in the Debye-Scherrer ring pattern have been recorded by scattering the 1.6 pC 3.5 MeV electron beam generated in the rf photoinjector off a 100-nm-thick Au foil. Dark current and high emittance particles are removed from the beam before sending it onto the diffraction target using a 1 mm diameter collimating hole. These results open the door to the study of irreversible phase transformations by single shot MeV electron diffraction.

High quality single shot diffraction patterns using ultrashort megaelectron volt electron beams from a radio frequency photoinjector

International Nuclear Information System (INIS)

Musumeci, P.; Moody, J. T.; Scoby, C. M.; Gutierrez, M. S.; Bender, H. A.; Wilcox, N. S.

2010-01-01

Single shot diffraction patterns using a 250-fs-long electron beam have been obtained at the UCLA Pegasus laboratory. High quality images with spatial resolution sufficient to distinguish closely spaced peaks in the Debye-Scherrer ring pattern have been recorded by scattering the 1.6 pC 3.5 MeV electron beam generated in the rf photoinjector off a 100-nm-thick Au foil. Dark current and high emittance particles are removed from the beam before sending it onto the diffraction target using a 1 mm diameter collimating hole. These results open the door to the study of irreversible phase transformations by single shot MeV electron diffraction.

Large patternable metal nanoparticle sheets by photo/e-beam lithography

Science.gov (United States)

Saito, Noboru; Wang, Pangpang; Okamoto, Koichi; Ryuzaki, Sou; Tamada, Kaoru

2017-10-01

Techniques for micro/nano-scale patterning of large metal nanoparticle sheets can potentially be used to realize high-performance photoelectronic devices because the sheets provide greatly enhanced electrical fields around the nanoparticles due to localized surface plasmon resonances. However, no single metal nanoparticle sheet currently exists with sufficient durability for conventional lithographical processes. Here, we report large photo and/or e-beam lithographic patternable metal nanoparticle sheets with improved durability by incorporating molecular cross-linked structures between nanoparticles. The cross-linked structures were easily formed by a one-step chemical reaction; immersing a single nanoparticle sheet consisting of core metals, to which capping molecules ionically bond, in a dithiol ethanol solution. The ligand exchange reaction processes were discussed in detail, and we demonstrated 20 μm wide line and space patterns, and a 170 nm wide line of the silver nanoparticle sheets.

Focused ion beam patterning to dielectrophoretically assemble single nanowire based devices

International Nuclear Information System (INIS)

La Ferrara, V; Massera, E; Francia, G Di; Alfano, B

2010-01-01

Direct-write processing is increasingly taking place in nanodevice fabrication. In this work, Focused Ion Beam (FIB), a powerful tool in maskless micromachining, is used for electrode patterning onto a silicon/silicon nitride substrate. Then a single palladium nanowire is assembled between electrodes by means of dielectrophoresis (DEP). The nanowire morphology depends on the electrode pattern when DEP conditions are fixed. FIB/DEP combination overcomes the problem of nanowire electrical contamination due to gallium ion bombardment and the as-grown nanowire retains its basic electrical properties. Single nanowire based devices have been fabricated with this novel approach and have been tested as hydrogen sensors, confirming the reliability of this technology.

Beam angle optimization for intensity-modulated radiation therapy using a guided pattern search method

International Nuclear Information System (INIS)

Rocha, Humberto; Dias, Joana M; Ferreira, Brígida C; Lopes, Maria C

2013-01-01

Generally, the inverse planning of radiation therapy consists mainly of the fluence optimization. The beam angle optimization (BAO) in intensity-modulated radiation therapy (IMRT) consists of selecting appropriate radiation incidence directions and may influence the quality of the IMRT plans, both to enhance better organ sparing and to improve tumor coverage. However, in clinical practice, most of the time, beam directions continue to be manually selected by the treatment planner without objective and rigorous criteria. The goal of this paper is to introduce a novel approach that uses beam’s-eye-view dose ray tracing metrics within a pattern search method framework in the optimization of the highly non-convex BAO problem. Pattern search methods are derivative-free optimization methods that require a few function evaluations to progress and converge and have the ability to better avoid local entrapment. The pattern search method framework is composed of a search step and a poll step at each iteration. The poll step performs a local search in a mesh neighborhood and ensures the convergence to a local minimizer or stationary point. The search step provides the flexibility for a global search since it allows searches away from the neighborhood of the current iterate. Beam’s-eye-view dose metrics assign a score to each radiation beam direction and can be used within the pattern search framework furnishing a priori knowledge of the problem so that directions with larger dosimetric scores are tested first. A set of clinical cases of head-and-neck tumors treated at the Portuguese Institute of Oncology of Coimbra is used to discuss the potential of this approach in the optimization of the BAO problem. (paper)

Fabrication of carbon quantum dots with nano-defined position and pattern in one step via sugar-electron-beam writing.

Science.gov (United States)

Weng, Yuyan; Li, Zhiyun; Peng, Lun; Zhang, Weidong; Chen, Gaojian

2017-12-14

Quantum dots (QDs) are promising materials in nanophotonics, biological imaging, and even quantum computing. Precise positioning and patterning of QDs is a prerequisite for realizing their actual applications. Contrary to the traditional two discrete steps of fabricating and positioning QDs, herein, a novel sugar-electron-beam writing (SEW) method is reported for producing QDs via electron-beam lithography (EBL) that uses a carefully chosen synthetic resist, poly(2-(methacrylamido)glucopyranose) (PMAG). Carbon QDs (CQDs) could be fabricated in situ through electron beam exposure, and the nanoscale position and luminescence intensity of the produced CQDs could be precisely controlled without the assistance of any other fluorescent matter. We have demonstrated that upon combining an electron beam with a glycopolymer, in situ production of CQDs occurs at the electron beam spot center with nanoscale precision at any place and with any patterns, an advancement that we believe will stimulate innovations in future applications.

Effect of Micro-Bubbles in Water on Beam Patterns of Parametric Array

Science.gov (United States)

Hashiba, Kunio; Masuzawa, Hiroshi

2003-05-01

The improvement in efficiency of a parametric array by nonlinear oscillation of micro-bubbles in water is studied in this paper. The micro-bubble oscillation can increase the nonlinear coefficient of the acoustic medium. The amplitude of the difference-frequency wave along the longitudinal axis and its beam patterns in the field including the layer with micro-bubbles were analyzed using a Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation. As a result, the largest improvement in efficiency was obtained and a narrow parametric beam was formed by forming a layer with micro-bubbles in front of a parametric sound radiator as thick as about the shock formation distance. If the layer becomes significantly thicker than the distance, the beam of the difference-frequency wave in the far-field will become broader. If the layer is significantly thinner than the distance, the intensity level of the wave in the far-field will be too low.

Contrast of HOLZ lines in energy-filtered convergent-beam electron diffraction patterns from silicon

International Nuclear Information System (INIS)

Lehmpfuhl, G.; Krahl, D.; Uchida, Y.

1995-01-01

Higher-order Laue-zone (HOLZ) lines were investigated in convergent-beam electron diffraction patterns from silicon near the low-indexed zone axes [100], [110] and [111]. The visibility of these lines depends on the effective structure potentials of the reflections from the first Laue zone depending on their Debye-Waller factor. The contrast of the HOLZ lines is strongly reduced by inelastically scattered electrons. They can be excluded by an imaging Ω filter for energy losses above 2 eV. The diffraction patterns were compared with many-beam calculations. Without absorption, an excellent agreement could be achieved for the [111] and [100] zone axes, while the simulation of the [110] zone-axis pattern needed a calculation with absorption. The reason for this observation is explained in the Bloch-wave picture. Calculations with absorption, however, lead to artefacts in the intensity distribution of the [100] HOLZ pattern. In order to obtain agreement with the experiment, the Debye-Waller factor had to be modified in different ways for the different zone axes. This corresponds to a strong anisotropy of the Debye-Waller factor. To confirm this observation, the temperature dependence of the itensity distributions of the HOLZ patterns was investigated between 50 and 680 K. At room temperature, the parameter D in the Debye-Waller factor exp(-Ds 2 ) was determined as 0.13, 0.26 and 0.55 A 2 for the zone axes [100], [111] and [110], respectively. The reliability of the conclusions is discussed. (orig.)

Modification and structuring of conducting polymer films on insulating substrates by ion beam treatment

International Nuclear Information System (INIS)

Asmus, T.; Wolf, Gerhard K.

2000-01-01

Besides the commonly used procedures of UV-, X-ray and electron beam lithography, surface structuring by ion beam processes represents an alternative route to receive patterns in the nanometre-micrometre scale. In this work we focused on changes of surface properties of the polymer materials induced by ion irradiation and on reproducing hexagonal and square patterns in the micrometre scale. To achieve a better understanding of modification and structuring of insulating and conducting polymers by ion beam treatment we investigated effects of 14 keV Ar + bombardment on thin films of doped conducting polyethoxithiophene (PEOT) and polyethylenedioxithiophene (PEDT) on polyethersulfone (PES) as insulating substrate within the fluence range from 10 14 to 10 17 ions/cm 2 . Changes of surface properties like wettability, solubility, topology and electrochemical behaviour have been studied by contact angle technique, AFM/LFM, cyclovoltammetry and electrochemical microelectrode. By irradiation through copper masks structured patterns were achieved. These patterns can be converted by galvanic or electroless copper deposition in structured metal layers

High-resolution electron-beam patternable nanocomposite containing metal nanoparticles for plasmonics

International Nuclear Information System (INIS)

Abargues, R; Marques-Hueso, J; Canet-Ferrer, J; Pedrueza, E; Valdes, J L; Jimenez, E; MartInez-Pastor, J P

2008-01-01

Polymer nanocomposites containing noble metal nanoparticles are promising materials for plasmonic applications. In this paper, we report on a high-resolution negative-tone nanocomposite resist based on poly(vinyl alcohol) where silver nanoparticles and nanopatterns are simultaneously generated by electron-beam lithography. Our results indicate nanostructures with a relatively high concentration of nanoparticles and, consequently, an electromagnetic coupling among the nanoparticles. Therefore, the patternable nanocomposite described in this work may be a suitable material for future plasmonic circuitry

Malfunctions of Implantable Cardiac Devices in Patients Receiving Proton Beam Therapy: Incidence and Predictors

International Nuclear Information System (INIS)

Gomez, Daniel R.; Poenisch, Falk; Pinnix, Chelsea C.; Sheu, Tommy; Chang, Joe Y.; Memon, Nada; Mohan, Radhe; Rozner, Marc A.; Dougherty, Anne H.

2013-01-01

Purpose: Photon therapy has been reported to induce resets of implanted cardiac devices, but the clinical sequelae of treating patients with such devices with proton beam therapy (PBT) are not well known. We reviewed the incidence of device malfunctions among patients undergoing PBT. Methods and Materials: From March 2009 through July 2012, 42 patients with implanted cardiac implantable electronic devices (CIED; 28 pacemakers and 14 cardioverter-defibrillators) underwent 42 courses of PBT for thoracic (23, 55%), prostate (15, 36%), liver (3, 7%), or base of skull (1, 2%) tumors at a single institution. The median prescribed dose was 74 Gy (relative biological effectiveness; range 46.8-87.5 Gy), and the median distance from the treatment field to the CIED was 10 cm (range 0.8-40 cm). Maximum proton and neutron doses were estimated for each treatment course. All CIEDs were checked before radiation delivery and monitored throughout treatment. Results: Median estimated peak proton and neutron doses to the CIED in all patients were 0.8 Gy (range 0.13-21 Gy) and 346 Sv (range 11-1100 mSv). Six CIED malfunctions occurred in 5 patients (2 pacemakers and 3 defibrillators). Five of these malfunctions were CIED resets, and 1 patient with a defibrillator (in a patient with a liver tumor) had an elective replacement indicator after therapy that was not influenced by radiation. The mean distance from the proton beam to the CIED among devices that reset was 7.0 cm (range 0.9-8 cm), and the mean maximum neutron dose was 655 mSv (range 330-1100 mSv). All resets occurred in patients receiving thoracic PBT and were corrected without clinical incident. The generator for the defibrillator with the elective replacement indicator message was replaced uneventfully after treatment. Conclusions: The incidence of CIED resets was about 20% among patients receiving PBT to the thorax. We recommend that PBT be avoided in pacing-dependent patients and that patients with any type of CIED receiving

Identification of LHC beam loss mechanism: a deterministic treatment of loss patterns

International Nuclear Information System (INIS)

Marsili, A.

2012-01-01

The goal of this work was to identify patterns in the beam loss profiles, both in their spatial distribution and time evolution. CERN's Large Hadron Collider (LHC) is the largest device ever built, with a total circumference of 26.7 km; and it is the most powerful accelerator ever, both in beam energy and beam intensity. The main magnets are superconducting, and contain the particles into two counter circulating beams which collide in four interaction points. CERN and the LHC will be described in chapter 1. The superconducting magnets of the LHC have to be protected against particle losses. Depending on the number of lost particles, the coils of the magnets could become normal conducting and/or will be damaged. To avoid these events a beam loss monitoring (BLM) system was installed to measure the particle loss rates. If the predefined safe thresholds of loss rates are exceeded, the beams are directed out of the accelerator ring towards the beam dump. The detectors of the BLM system are mainly ionization chambers located outside of the cryostats. In total, about 3600 ionisation chambers are installed. Further challenges include the high dynamical range of losses (chamber currents ranging between 2 pA and 1 mA). The BLM system will be further described in chapter 2. The subject of this thesis is to study the loss patterns and nd the origin of the losses in a deterministic way, by comparing measured losses to well understood loss scenarios. This is done through a case study: different techniques were used on a restrained set of loss scenarios, as a proof of concept of the possibility to extract information from a loss profile. Finding the origin of the losses should allow acting in response. A justification of the doctoral work will be given at the end of chapter 2. This thesis will then focus on the theoretical understanding and the implementation of the decomposition of a measured loss profile as a linear combination of the reference scenarios; and the evaluation of

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

Decoding algorithm for vortex communications receiver

Science.gov (United States)

Kupferman, Judy; Arnon, Shlomi

2018-01-01

Vortex light beams can provide a tremendous alphabet for encoding information. We derive a symbol decoding algorithm for a direct detection matrix detector vortex beam receiver using Laguerre Gauss (LG) modes, and develop a mathematical model of symbol error rate (SER) for this receiver. We compare SER as a function of signal to noise ratio (SNR) for our algorithm and for the Pearson correlation algorithm. To our knowledge, this is the first comprehensive treatment of a decoding algorithm of a matrix detector for an LG receiver.

Receivers for processing electron beam pick-up electrode signals

International Nuclear Information System (INIS)

Anon.

1991-01-01

There are several methods of determining the transverse position of the electron beam, based upon sensing either the electric field, the magnetic field, or both. At the NSLS the transverse beam position monitors each consist of a set of four circular electrodes. There are 48 sets of pick-up electrodes in the X-ray ring and 24 in the VUV storage ring for determining the electron orbit, and a few extra sets installed for specialized purposes. When the beam passes between the four electrodes, charge is induced on each electrode, the amount depending upon the distance of the beam from that electrode. If V a , V b , V c and V d given by a difference between pairs of electrodes normalized for variations in beam current by dividing by the sum of electrode voltages. The method of processing these signals depends upon their time structure. The electrons circulating around the vacuum chamber are concentrated in short bunches within stability buckets produced by the accelerating voltage in the RF cavities. The charges induced on the pickup electrodes then are narrow pulses, a fraction of a nanosecond long, and would result in a monopolar voltage pulses if it were not for the impedance of the cable connecting the electrode to the processing apparatus. The capacitance between each electrode and the chamber wall is only a few picofarads and is effectively in parallel with the cable impedance (50 ohms). Thus an appreciable amount of the charge flows off the electrode while the bunch is between the electrodes, resulting in potential of opposite sign as the bunch is leaving the vicinity of the electrode. The resulting signal consists of a series of bipolar pulses, each of less than one nanosecond duration

Temporal and spatial patterns of micropollutants in urban receiving waters

Energy Technology Data Exchange (ETDEWEB)

Musolff, Andreas, E-mail: andreas.musolff@ufz.d [UFZ - Helmholtz Centre for Environmental Research, Department of Hydrogeology, Permoserstr. 15, 04318 Leipzig (Germany); Leschik, Sebastian, E-mail: sebastian.leschik@ufz.d [UFZ - Helmholtz Centre for Environmental Research, Department of Hydrogeology, Permoserstr. 15, 04318 Leipzig (Germany); Moeder, Monika, E-mail: monika.moeder@ufz.d [UFZ - Helmholtz Centre for Environmental Research, Department of Analytical Chemistry, Permoserstr. 15, 04318 Leipzig (Germany); Strauch, Gerhard, E-mail: gerhard.strauch@ufz.d [UFZ - Helmholtz Centre for Environmental Research, Department of Hydrogeology, Permoserstr. 15, 04318 Leipzig (Germany); Reinstorf, Frido, E-mail: frido.reinstorf@hs-magdeburg.d [University of Applied Sciences Magdeburg-Stendal, Department of Water and Waste Management, Breitscheidstr. 2, 39114 Magdeburg (Germany); Schirmer, Mario, E-mail: mario.schirmer@eawag.c [Eawag, The Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and Drinking Water, Ueberlandstr. 133, 8600 Duebendorf (Switzerland)

2009-11-15

Based on a monitoring program over the course of a year, we characterize the temporal and spatial distribution of selected micropollutants in an urban watershed within the city of Leipzig, Germany. Micropollutants revealed a ubiquitous presence in untreated and treated wastewater, surface water and groundwater. The loads of 4-nonylphenol in the effluents of the municipal wastewater treatment plant followed a seasonal trend, whereas the loads of all other micropollutants were highly variable and not correlated to seasons. In the surface water, load seasonality of caffeine, galaxolide and tonalide resulted from a rapid removal with increased water temperature. The loads of 4-nonylphenol and of caffeine in the colder months increased when rainfall occurred. In the groundwater, complex spatial and temporal patterns were apparent and were related to varying input, retardation and removal processes. As a consequence, an assessment of micropollutants in urban waters should consider different micropollutants' temporal and spatial variability. - Micropollutants in urban receiving waters are characterized by variable temporal and spatial concentration and load patterns that have to be considered in risk assessments.

Technical Note: Validation of halo modeling for proton pencil beam spot scanning using a quality assurance test pattern

Energy Technology Data Exchange (ETDEWEB)

Lin, Liyong, E-mail: linl@uphs.upenn.edu; Huang, Sheng; Kang, Minglei; Solberg, Timothy D.; McDonough, James E.; Ainsley, Christopher G. [Department of Radiation Oncology, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, Pennsylvania 19104 (United States)

2015-09-15

Purpose: The purpose of this paper is to demonstrate the utility of a comprehensive test pattern in validating calculation models that include the halo component (low-dose tails) of proton pencil beam scanning (PBS) spots. Such a pattern has been used previously for quality assurance purposes to assess spot shape, position, and dose. Methods: In this study, a scintillation detector was used to measure the test pattern in air at isocenter for two proton beam energies (115 and 225 MeV) of two IBA universal nozzles (UN #1 and UN #2). Planar measurements were compared with calculated dose distributions based on the weighted superposition of location-independent (UN #1) or location-dependent (UN #2) spot profiles, previously measured using a pair-magnification method and between two nozzles. Results: Including the halo component below 1% of the central dose is shown to improve the gamma-map comparison between calculation and measurement from 94.9% to 98.4% using 2 mm/2% criteria for the 115 MeV proton beam of UN #1. In contrast, including the halo component below 1% of the central dose does not improve the gamma agreement for the 115 MeV proton beam of UN #2, due to the cutoff of the halo component at off-axis locations. When location-dependent spot profiles are used for calculation instead of spot profiles at central axis, the gamma agreement is improved from 98.0% to 99.5% using 2 mm/2% criteria. The two nozzles clearly have different characteristics, as a direct comparison of measured data shows a passing rate of 89.7% for the 115 MeV proton beam. At 225 MeV, the corresponding gamma comparisons agree better between measurement and calculation, and between measurements in the two nozzles. Conclusions: In addition to confirming the primary component of individual PBS spot profiles, a comprehensive test pattern is useful for the validation of the halo component at off-axis locations, especially for low energy protons.

Problems in nonlinear acoustics: Pulsed finite amplitude sound beams, nonlinear acoustic wave propagation in a liquid layer, nonlinear effects in asymmetric cylindrical sound beams, effects of absorption on the interaction of sound beams, and parametric receiving arrays

Science.gov (United States)

Hamilton, Mark F.

1990-12-01

This report discusses five projects all of which involve basic theoretical research in nonlinear acoustics: (1) pulsed finite amplitude sound beams are studied with a recently developed time domain computer algorithm that solves the KZK nonlinear parabolic wave equation; (2) nonlinear acoustic wave propagation in a liquid layer is a study of harmonic generation and acoustic soliton information in a liquid between a rigid and a free surface; (3) nonlinear effects in asymmetric cylindrical sound beams is a study of source asymmetries and scattering of sound by sound at high intensity; (4) effects of absorption on the interaction of sound beams is a completed study of the role of absorption in second harmonic generation and scattering of sound by sound; and (5) parametric receiving arrays is a completed study of parametric reception in a reverberant environment.

Measured and simulated heavy-ion beam loss patterns at the CERN Large Hadron Collider

Science.gov (United States)

Hermes, P. D.; Bruce, R.; Jowett, J. M.; Redaelli, S.; Salvachua Ferrando, B.; Valentino, G.; Wollmann, D.

2016-05-01

The Large Hadron Collider (LHC) at CERN pushes forward to new regimes in terms of beam energy and intensity. In view of the combination of very energetic and intense beams together with sensitive machine components, in particular the superconducting magnets, the LHC is equipped with a collimation system to provide protection and intercept uncontrolled beam losses. Beam losses could cause a superconducting magnet to quench, or in the worst case, damage the hardware. The collimation system, which is optimized to provide a good protection with proton beams, has shown a cleaning efficiency with heavy-ion beams which is worse by up to two orders of magnitude. The reason for this reduced cleaning efficiency is the fragmentation of heavy-ion beams into isotopes with a different mass to charge ratios because of the interaction with the collimator material. In order to ensure sufficient collimation performance in future ion runs, a detailed theoretical understanding of ion collimation is needed. The simulation of heavy-ion collimation must include processes in which 82 + 208Pb ions fragment into dozens of new isotopes. The ions and their fragments must be tracked inside the magnetic lattice of the LHC to determine their loss positions. This paper gives an overview of physical processes important for the description of heavy-ion loss patterns. Loss maps simulated by means of the two tools ICOSIM [1,2] and the newly developed STIER (SixTrack with Ion-Equivalent Rigidities) are compared with experimental data measured during LHC operation. The comparison shows that the tool STIER is in better agreement.

Surface structuring in polypropylene using Ar+ beam sputtering: Pattern transition from ripples to dot nanostructures

Science.gov (United States)

Goyal, Meetika; Aggarwal, Sanjeev; Sharma, Annu; Ojha, Sunil

2018-05-01

Temporal variations in nano-scale surface morphology generated on Polypropylene (PP) substrates utilizing 40 keV oblique argon ion beam have been presented. Due to controlled variation of crucial beam parameters i.e. ion incidence angle and erosion time, formation of ripple patterns and further its transition into dot nanostructures have been realized. Experimental investigations have been supported by evaluation of Bradley and Harper (B-H) coefficients estimated using SRIM (The Stopping and Range of Ions in Matter) simulations. Roughness of pristine target surfaces has been accredited to be a crucial factor behind the early time evolution of nano-scale patterns over the polymeric surface. Study of Power spectral density (PSD) spectra reveals that smoothing mechanism switch from ballistic drift to ion enhanced surface diffusion (ESD) which can be the most probable cause for such morphological transition under given experimental conditions. Compositional analysis and depth profiling of argon ion irradiated specimens using Rutherford Backscattering Spectroscopy (RBS) has also been correlated with the AFM findings.

Process time optimization of robotic remote laser cutting by utilizing customized beam patterns and redundancy space task sequencing

DEFF Research Database (Denmark)

Villumsen, Sigurd

This dissertation is written as a part of the ROBOCUT project which concerns the development of a new laser cutting technology that seeks to increase the performance of traditional and remote laser cutting by using beam shaping technologies. The resulting customized beam patterns are obtained by ...... axes of the laser cutting system and transforming the sequencing problem into a generalized traveling salesman problem (GTSP)....

High-resolution, high-throughput, positive-tone patterning of poly(ethylene glycol by helium beam exposure through stencil masks.

Directory of Open Access Journals (Sweden)

Eliedonna E Cacao

Full Text Available In this work, a collimated helium beam was used to activate a thiol-poly(ethylene glycol (SH-PEG monolayer on gold to selectively capture proteins in the exposed regions. Protein patterns were formed at high throughput by exposing a stencil mask placed in proximity to the PEG-coated surface to a broad beam of helium particles, followed by incubation in a protein solution. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR spectra showed that SH-PEG molecules remain attached to gold after exposure to beam doses of 1.5-60 µC/cm(2 and incubation in PBS buffer for one hour, as evidenced by the presence of characteristic ether and methoxy peaks at 1120 cm(-1 and 2870 cm(-1, respectively. X-ray Photoelectron Spectroscopy (XPS spectra showed that increasing beam doses destroy ether (C-O bonds in PEG molecules as evidenced by the decrease in carbon C1s peak at 286.6 eV and increased alkyl (C-C signal at 284.6 eV. XPS spectra also demonstrated protein capture on beam-exposed PEG regions through the appearance of a nitrogen N1s peak at 400 eV and carbon C1s peak at 288 eV binding energies, while the unexposed PEG areas remained protein-free. The characteristic activities of avidin and horseradish peroxidase were preserved after attachment on beam-exposed regions. Protein patterns created using a 35 µm mesh mask were visualized by localized formation of insoluble diformazan precipitates by alkaline phosphatase conversion of its substrate bromochloroindoyl phosphate-nitroblue tetrazolium (BCIP-NBT and by avidin binding of biotinylated antibodies conjugated on 100 nm gold nanoparticles (AuNP. Patterns created using a mask with smaller 300 nm openings were detected by specific binding of 40 nm AuNP probes and by localized HRP-mediated deposition of silver nanoparticles. Corresponding BSA-passivated negative controls showed very few bound AuNP probes and little to no enzymatic formation of diformazan precipitates or silver

Second-order temporal interference of two independent light beams at an asymmetrical beam splitter

International Nuclear Information System (INIS)

Liu Jianbin; Wang Jingjing; Xu Zhuo

2017-01-01

The second-order temporal interference of classical and nonclassical light at an asymmetrical beam splitter is discussed based on two-photon interference in Feynman’s path integral theory. The visibility of the second-order interference pattern is determined by the properties of the superposed light beams, the ratio between the intensities of these two light beams, and the reflectivity of the asymmetrical beam splitter. Some requirements about the asymmetrical beam splitter have to be satisfied in order to ensure that the visibility of the second-order interference pattern of nonclassical light beams exceeds the classical limit. The visibility of the second-order interference pattern of photons emitted by two independent single-photon sources is independent of the ratio between the intensities. These conclusions are important for the researches and applications in quantum optics and quantum information when an asymmetrical beam splitter is employed. (paper)

Dual patterning of a poly(acrylic acid) layer by electron-beam and block copolymer lithographies.

Science.gov (United States)

Pearson, Anthony C; Linford, Matthew R; Harb, John N; Davis, Robert C

2013-06-18

We show the controllable patterning of palladium nanoparticles in both one and two dimensions using electron-beam lithography and reactive ion etching of a thin film of poly(acrylic acid) (PAA). After the initial patterning of the PAA, a monolayer of polystyrene-b-poly-2-vinylpyridine micelles is spun cast onto the surface. A short reactive ion etch is then used to transfer the micelle pattern into the patterned poly(acrylic acid). Finally, PdCl2 is loaded from solution into the patterned poly(acrylic acid) features, and a reactive-ion etching process is used to remove the remaining polymer and form Pd nanoparticles. This method yields location-controlled patches of nanoparticles, including single- and double-file lines and nanoparticle pairs. A locational accuracy of 9 nm or less in one direction was achieved by optimizing the size of the PAA features.

Sub-micrometric surface texturing of AZ31 Mg-alloy through two-beam direct laser interference patterning with a ns-pulsed green fiber laser

Science.gov (United States)

Furlan, Valentina; Biondi, Marco; Demir, Ali Gökhan; Pariani, Giorgio; Previtali, Barbara; Bianco, Andrea

2017-11-01

Two-beam direct laser interference patterning (DLIP) is the method that employs two beams and provides control over the pattern geometry by regulating the angle between the beams and the wavelength of the beam. Despite the simplistic optical arrangement required for the method, the feasibility of sub-micrometric patterning of a surface depends on the correct manipulation of the process parameters, especially in the case of metallic materials. Magnesium alloys, from this point of view, exhibit further difficulty in processability due to low melting point and high reactivity. With biocompatibility and biodegradability features, Mg-alloy implants can take further advantage of surface structuring for tailoring the biological behaviour. In this work, a two-beam DLIP setup has been developed employing an industrial grade nanosecond-pulsed fiber laser emitting at 532 nm. The high repetition rate and ramped pulse profile provided by the laser were exploited for a more flexible control over the energy content deposited over the heat-sensitive Mg-alloy. The paper describes the strategies developed for controlling ramped laser emission at 20 kHz repetition rate. The process feasibility window was assessed within a large range of parameters. Within the feasibility window, a complete experimental plan was applied to investigate the effect of main laser process parameters on the pattern dimensions. Periodic surface structures with good definition down to 580 nm ± 20 nm spacing were successfully produced.

High Gain Advanced GPS Receiver

National Research Council Canada - National Science Library

Brown, Alison; Zhang, Gengsheng

2006-01-01

NAVSYS High Gain Advanced GPS Receiver (HAGR) uses a digital beam-steering antenna array to enable up to eight GPS satellites to be tracked, each with up to 10 dBi of additional antenna gain over a conventional receiver solution...

Terahertz quantum cascade laser as local oscillator in a heterodyne receiver.

Science.gov (United States)

Hübers, Heinz-Wilhelm; Pavlov, S; Semenov, A; Köhler, R; Mahler, L; Tredicucci, A; Beere, H; Ritchie, D; Linfield, E

2005-07-25

Terahertz quantum cascade lasers have been investigated with respect to their performance as a local oscillator in a heterodyne receiver. The beam profile has been measured and transformed in to a close to Gaussian profile resulting in a good matching between the field patterns of the quantum cascade laser and the antenna of a superconducting hot electron bolometric mixer. Noise temperature measurements with the hot electron bolometer and a 2.5 THz quantum cascade laser yielded the same result as with a gas laser as local oscillator.

Simulation of AZ-PN100 resist pattern fluctuation in X-ray lithography, including synchrotron beam polarization

International Nuclear Information System (INIS)

Scheckler, E.W.; Ogawa, Taro; Tanaka, Toshihiko; Takeda, Eiji; Oizumi, Hiroaki.

1993-01-01

A new simulation model for nanometer-scale pattern fluctuation in X-ray lithography is presented and applied to a study of AZ-PN100 negative chemical amplification resist. The exposure simulation considers polarized photons from a synchrotron radiation (SR) source. Monte Carlo simulation of Auger and photoelectron generation is followed by electron scattering simulation to determine the deposited energy distribution at the nanometer scale, including beam polarization effects. An acid-catalyst random walk model simulates the post-exposure bake (PEB) step. Fourier transform infrared (FTIR) spectroscopy and developed resist thickness measurements are used to fit PEB and rate models for AZ-PN100. A polymer removal model for development simulation predicts the macroscopic resist shape and pattern roughness. The simulated 3σ linewidth variation is in excess of 24 nm. Simulation also shows a detrimental effect if the beam polarization is perpendicular to the line. Simulation assuming a theoretical ideal exposure yields a 50 nm minimum line for standard process conditions. (author)

Study of image reconstruction for terahertz indirect holography with quasi-optics receiver.

Science.gov (United States)

Gao, Xiang; Li, Chao; Fang, Guangyou

2013-06-01

In this paper, an indirect holographic image reconstruction algorithm was studied for terahertz imaging with a quasi-optics receiver. Based on the combination of the reciprocity principle and modified quasi-optics theory, analytical expressions of the received spatial power distribution and its spectrum are obtained for the interference pattern of target wave and reference wave. These results clearly give the quantitative relationship between imaging quality and the parameters of a Gaussian beam, which provides a good criterion for terahertz quasi-optics transceivers design in terahertz off-axis holographic imagers. To validate the effectiveness of the proposed analysis method, some imaging results with a 0.3 THz prototype system are shown based on electromagnetic simulation.

Spontaneous decoration of Au nanoparticles on micro-patterned reduced graphene oxide shaped by focused laser beam

International Nuclear Information System (INIS)

Wan, Y. C.; Tok, E. S.; Teoh, H. F.; Sow, C. H.

2015-01-01

We report a facile, two-step method for the micro-landscaping of Au nanoparticles(NPs) on reduced graphene oxide (rGO) film en route to micro-patterned Au(NPs)-rGO hybrid functional materials. This method employs a focused laser beam to first locally convert GO to rGO before immersing the micro-patterned GO-rGO film into HAuCl 4 solution. The rGO micro-pattern, shaped by the focused laser beam, serves as nucleation sites for the reduction of Au ions. The reduction mechanism that governs the decoration of Au NPs on rGO films is akin to electroless deposition process. In this instance, surface charges that are formed during laser reduction of GO to rGO provide active nucleation sites for Au 3+ ions to form Au NPs when HAuCl 4 solution is introduced. The number density, the size, and size distribution of the Au NPs can thus be directly tuned and preferentially anchored onto the rGO micro-pattern by varying the incident laser power, the scanning speed of the laser, or the concentration of HAuCl 4 . The resulting hybrid materials can be used as a substrate for Surface Enhanced Raman Spectroscopy (SERS). Using Rhodamine 6G as the test subject, we found an improvement of SERS enhancement over bare rGO of up to four times, depending on the size of the Au NPs

Spontaneous decoration of Au nanoparticles on micro-patterned reduced graphene oxide shaped by focused laser beam

Energy Technology Data Exchange (ETDEWEB)

Wan, Y. C.; Tok, E. S. [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Teoh, H. F. [Graduate School of Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore 117456 (Singapore); Sow, C. H. [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Graduate School of Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore 117456 (Singapore)

2015-02-07

We report a facile, two-step method for the micro-landscaping of Au nanoparticles(NPs) on reduced graphene oxide (rGO) film en route to micro-patterned Au(NPs)-rGO hybrid functional materials. This method employs a focused laser beam to first locally convert GO to rGO before immersing the micro-patterned GO-rGO film into HAuCl{sub 4} solution. The rGO micro-pattern, shaped by the focused laser beam, serves as nucleation sites for the reduction of Au ions. The reduction mechanism that governs the decoration of Au NPs on rGO films is akin to electroless deposition process. In this instance, surface charges that are formed during laser reduction of GO to rGO provide active nucleation sites for Au{sup 3+} ions to form Au NPs when HAuCl{sub 4} solution is introduced. The number density, the size, and size distribution of the Au NPs can thus be directly tuned and preferentially anchored onto the rGO micro-pattern by varying the incident laser power, the scanning speed of the laser, or the concentration of HAuCl{sub 4}. The resulting hybrid materials can be used as a substrate for Surface Enhanced Raman Spectroscopy (SERS). Using Rhodamine 6G as the test subject, we found an improvement of SERS enhancement over bare rGO of up to four times, depending on the size of the Au NPs.

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...

Molecular-beam epitaxy on shallow mesa gratings patterned on GaAs(311)A and (100) substrates

NARCIS (Netherlands)

Gong, Q.; Nötzel, R.; Schönherr, H.-P.; Ploog, K.H.

2002-01-01

We report on the morphology and properties of the surface formed by molecular-beam epitaxy on shallow mesa gratings on patterned GaAs(311)A and GaAs(100). On GaAs(311)A substrates, the corrugated surface formed after GaAs growth on shallow mesa gratings along [011] is composed of monolayer high

Velocity measurements and identification of the flow pattern of vertical air-water flows with light-beam detectors

International Nuclear Information System (INIS)

Luebbesmeyer, D.; Leoni, B.

1980-07-01

A new detector for measuring fluid velocities in two-phase flows by means of Noise-Analysis (especially Transient-Cross-Correlation-technique) has been developed. The detector utilizes a light-beam which is modulated by changes in the transparency of the two-phase flow. The results of nine measurements for different flow-regimes of vertical air/water-flows are shown. A main topic of these investigations was to answer the question if it is possible to identify the flow-pattern by looking at the shape of different 'Noise-Analytical-functions' (like APSD, CPSD, CCF etc.). The results prove that light-beam sensors are good detectors for fluid-velocity measurements in different flow regimes and in a wide range of fluid velocities starting with values of about 0.08 m/s up to values of 40 m/s. With respect to flow-pattern identification only the time-signals and the shape of the cross-power-density-function (CPSD) seem to be useful. (Auth.)

Nucleation sites of Ge nanoislands grown on pit-patterned Si substrate prepared by electron-beam lithography

Science.gov (United States)

Smagina, Zh. V.; Zinovyev, V. A.; Rudin, S. A.; Novikov, P. L.; Rodyakina, E. E.; Dvurechenskii, A. V.

2018-04-01

Regular pit-patterned Si(001) substrates were prepared by electron-beam lithography followed by plasma chemical etching. The geometry of the pits was controlled by varying the etching conditions and the electron-beam exposure duration. It was shown that the location of three-dimensional (3D) Ge nanoislands subsequently grown on the pit-patterned Si substrates depends on the shape of the pit bottom. In the case of pits having a sharp bottom, 3D Ge islands nucleate inside the pits. For pits with a wide flat bottom, the 3D Ge island nucleation takes place at the pit periphery. This effect is attributed to the strain relaxation depending not only on the initial pit shape, but also on its evolution during the Ge wetting layer deposition. It was shown by Monte Carlo simulations that in the case of a pit with a pointed bottom, the relaxation is most effective inside the pit, while for a pit with a wide bottom, the most relaxed area migrates during Ge deposition from the pit bottom to its edges, where 3D Ge islands nucleate.

Low-level software for the pentek 6510 digital receiver board applied to the new AD beam measurement system

CERN Document Server

Angoletta, Maria Elena

2002-01-01

The new beam measurement system for the CERN Antiproton Decelerator heavily relies on a Pentek 6510 Digital Receiver (DRX) board. The new system goal is to extract beam parameters from pickup signals. Its digital implementation allows for higher precision, easier management of the hardware as well as modification and improvement with no hardware change. In this scheme, this innovative VME DRX board is responsible for parallel data acquisition, independent digital down conversion and processing of up to 4 digitised inputs. The in-house- developed low-level code (LLC), running on the board, takes care of several tasks, such as interfacing with the Real Time Task (RTT), data processing and board managing. The RTT runs on a PowerPC VME board and controls the DRX board as a master. The LLC is a state machine developed in C and Assembler, which services several interrupts and performs the FFT of complex input data. The DRX low-level system developed is highly modular and easily adaptable to other processing scenari...

Ion-beam plasma and propagation of intense compensated ion beams

Energy Technology Data Exchange (ETDEWEB)

Gabovich, M D [AN Ukrainskoj SSR, Kiev. Inst. Fiziki

1977-02-01

Discussed are the results of investigation of plasma properties received by neutralization of intense ion beam space charge. Considered is the process of ion beam compensation by charges, formed as a result of gas ionization by this beam or by externally introduced ones. Emphasis is placed on collective phenomena in ion-beam plasma, in particular on non-linear effects limiting amplitude of oscillations. It is shown that not only dynamic decompensation but the Coulomb collisions of ions with electrons as well as other collective oscillations significantly affects the propagation of compensated ion beams. All the processes are to be taken into account in solving the problem of obtaining ''superdense'' compensated beams.

Field effect transistors and photodetectors based on nanocrystalline graphene derived from electron beam induced carbonaceous patterns

International Nuclear Information System (INIS)

Kurra, Narendra; Bhadram, Venkata Srinu; Narayana, Chandrabhas; Kulkarni, G U

2012-01-01

We describe a transfer-free method for the fabrication of nanocrystalline graphene (nc-graphene) on SiO 2 substrates directly from patterned carbonaceous deposits. The deposits were produced from the residual hydrocarbons present in the vacuum chamber without any external source by using an electron beam induced carbonaceous deposition (EBICD) process. Thermal treatment under vacuum conditions in the presence of Ni catalyst transformed the EBIC deposit into nc-graphene patterns, confirmed using Raman and TEM analysis. The nc-graphene patterns have been employed as an active p-type channel material in a field effect transistor (FET) which showed a hole mobility of ∼90 cm 2 V −1 s −1 . The nc-graphene also proved to be suitable material for IR detection. (paper)

Comparison between intensity modulated radiotherapy (IMRT) and 3D tangential beams technique used in patients with early-stage breast cancer who received breast-conserving therapy

International Nuclear Information System (INIS)

Sas-Korczynska, B.; Kokoszka, A.; Korzeniowski, S.; Sladowska, A.; Rozwadowska-Bogusz, B.; Lesiak, J.; Dyczek, S.

2010-01-01

Background: The most often found complications in patients with breast cancer who received radiotherapy are cardiac and pulmonary function disorders and development of second malignancies. Aim: To compare the intensity modulated radiotherapy with the 3D tangential beams technique in respect of dose distribution in target volume and critical organs they generate in patients with early-stage breast cancer who received breast-conserving therapy. Materials and methods: A dosimetric analysis was performed to assess the three radiotherapy techniques used in each of 10 consecutive patients with early-stage breast cancer treated with breast-conserving therapy. Radiotherapy was planned with the use of all the three techniques: 3D tangential beams with electron boost, IMRT with electron boost, and intensity modulated radiotherapy with simultaneous integrated boost. Results: The use of the IMRT techniques enables more homogenous dose distribution in target volume. The range of mean and median dose to the heart and lung was lower with the IMRT techniques in comparison to the 3D tangential beams technique. The range of mean dose to the heart amounted to 0.3 - 3.5 Gy for the IMRT techniques and 0.4 - 4.3 for the tangential beams technique. The median dose to the lung on the irradiated side amounted to 4.9 - 5 Gy for the IMRT techniques and 5.6 Gy for the 3D tangential beams technique. Conclusion: The application of the IMRT techniques in radiotherapy patients with early-stage breast cancer allows to obtain more homogenous dose distribution in target volume, while permitting to reduce the dose to critical organs. (authors)

Resolution Improvement and Pattern Generator Development for the Maskless Micro-Ion-Beam Reduction Lithography System

International Nuclear Information System (INIS)

Jiang, Ximan

2006-01-01

have been studied. The dependence of the throughput with the exposure field size and the speed of the mechanical stage has been investigated. In order to perform maskless lithography, different micro-fabricated pattern generators have been developed for the MMRL system. Ion beamlet switching has been successfully demonstrated on the MMRL system. A positive bias voltage around 10 volts is sufficient to switch off the ion current on the micro-fabricated pattern generators. Some unexpected problems, such as the high-energy secondary electron radiations, have been discovered during the experimental investigation. Thermal and structural analysis indicates that the aperture displacement error induced by thermal expansion can satisfy the 3(delta) CD requirement for lithography nodes down to 25 nm. The cross-talking effect near the surface and inside the apertures of the pattern generator has been simulated in a 3-D ray-tracing code. New pattern generator design has been proposed to reduce the cross-talking effect. In order to eliminate the surface charging effect caused by the secondary electrons, a new beam-switching scheme in which the switching electrodes are immersed in the plasma has been demonstrated on a mechanically fabricated pattern generator

A deep convolutional neural network to analyze position averaged convergent beam electron diffraction patterns.

Science.gov (United States)

Xu, W; LeBeau, J M

2018-05-01

We establish a series of deep convolutional neural networks to automatically analyze position averaged convergent beam electron diffraction patterns. The networks first calibrate the zero-order disk size, center position, and rotation without the need for pretreating the data. With the aligned data, additional networks then measure the sample thickness and tilt. The performance of the network is explored as a function of a variety of variables including thickness, tilt, and dose. A methodology to explore the response of the neural network to various pattern features is also presented. Processing patterns at a rate of  ∼ 0.1 s/pattern, the network is shown to be orders of magnitude faster than a brute force method while maintaining accuracy. The approach is thus suitable for automatically processing big, 4D STEM data. We also discuss the generality of the method to other materials/orientations as well as a hybrid approach that combines the features of the neural network with least squares fitting for even more robust analysis. The source code is available at https://github.com/subangstrom/DeepDiffraction. Copyright © 2018 Elsevier B.V. All rights reserved.

Performance Evaluation of Irbene RT-16 Radio Telescope Receiving System

Directory of Open Access Journals (Sweden)

Bleiders M.

2017-12-01

Full Text Available In the present paper, recent measurement results of refurbished Irbene RT-16 radio telescope receiving system performance are presented. The aim of the research is to evaluate characteristics of RT-16, which will allow carrying out necessary amplitude calibration in both single dish and VLBI observations, to improve the performance of existing system as well as to monitor, control and compare performance if possible changes in the receiving system will occur in future. The evaluated receiving system is 16 m Cassegrain antenna equipped with a cryogenic receiver with frequency range from 4.5 to 8.8 GHz, which is divided into four sub-bands. Multiple calibration sessions have been carried out by observing stable astronomical sources with known flux density by using in-house made total power registration backend. First, pointing offset calibration has been carried out and pointing model coefficients calculated and applied. Then, amplitude calibration, namely antenna sensitivity, calibration diode equivalent flux density and gain curve measurements have been carried out by observing calibration sources at different antenna elevations at each of the receiver sub-bands. Beam patterns have also been evaluated at different frequency bands. As a whole, acquired data will serve as a reference point for comparison in future performance evaluation of RT-16.

PDMS patterning by proton beam

International Nuclear Information System (INIS)

Szilasi, S.Z.; Huszank, R.; Csik, A.; Rajta, I.; Cserhati, C.

2008-01-01

Complete text of publication follows. In this paper the poly-(dimethylsiloxane) (PDMS) is introduced as a resist material for proton beam writing. We were looking for a biocompatible micropatternable polymer in which the chemical structure changes significantly due to proton beam exposure making the polymer capable of proton beam writing. PDMS is a commonly used silicon-based organic polymer, optically clear, and generally considered to be inert, non-toxic biocompatible polymer. PDMS is also notably hydrophobic, meaning that water cannot easily penetrate its surface. This property has led extended use of PDMS in microfluidics too. PDMS is a crosslinkable polymer, it acts like a rubbery solid when it is cross-linked. In this state, the polymer does not deform permanently under stress or strain. Up to now the PDMS has been used as a casting or replicating material in microfabrication to form microchannels, micromolding, or creating microstamps, etc. PDMS has not been used as a resist material for direct write techniques. In this work we investigated the surface topography of the irradiated regions of PDMS under and without stress (on the cut surface and on the original fluid surface, respectively). In the samples wherein stress was not developed, noticeable compaction was observed. In case of those samples wherein stress was developed, noticeable swelling occurred. During the irradiation around the actual position of the beam spot we experienced significant swelling that reduced in time. To determine the large scale remaining changes in the surface topography at the cut edges of the samples we used Scanning Electron Microscope (SEM). After numerous profilometer measurements we experienced that the irradiated areas became harder, so the probe could move on it without sinking. The unirradiated areas of the PDMS were so soft, that the probe sank in the medium even with the smallest load (5 x 10 -7 N). Because of this phenomenon the irradiated areas seem to be higher

Effect of beam condition in variable-shaped electron-beam direct writing for 0.25 μm and below

International Nuclear Information System (INIS)

Hirasawa, S.; Nakajima, K.; Tamura, T.; Aizaki, N.

1993-01-01

The effect of incident electron-beam conditions, which are acceleration voltage and beam blur of variable-shaped electron-beam direct writing, is investigated using the deposited energy distribution to realize a fine pattern of ≤0.25 μm in trilayer resist process. The deposited energy distribution is calculated using a three-dimensional Monte Carlo method. In a trilayer resist system, a thin bottom resist layer can be used, because the contrast value derived from the Monte Carlo calculation is independent of the bottom layer thickness. The beam blur of 0.05 μm does not degrade 0.25 μm line-and-space (L/S) patterns, but seriously degrades 0.1 μm L/S patterns. Higher acceleration voltage is effective for improving the contrast. At lower acceleration voltage, the slope of the deposited energy profile defined at the resist bottom is mainly influenced by electron scattering. On the other hand, at higher acceleration voltage, the slope of deposited energy profile mainly depends on the beam blur. The 0.1 μm L/S patterns are expected to be resolved at 30 kV when there is less than 0.02 μm beam blur with trilayer resist system. The possibility of using a single layer resist process for 0.1 μm L/S pattern will be barely realized at the conditions of 50 kV and 0.02 μm beam blur

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...

Assessment of local variability by high-throughput e-beam metrology for prediction of patterning defect probabilities

Science.gov (United States)

Wang, Fuming; Hunsche, Stefan; Anunciado, Roy; Corradi, Antonio; Tien, Hung Yu; Tang, Peng; Wei, Junwei; Wang, Yongjun; Fang, Wei; Wong, Patrick; van Oosten, Anton; van Ingen Schenau, Koen; Slachter, Bram

2018-03-01

We present an experimental study of pattern variability and defectivity, based on a large data set with more than 112 million SEM measurements from an HMI high-throughput e-beam tool. The test case is a 10nm node SRAM via array patterned with a DUV immersion LELE process, where we see a variation in mean size and litho sensitivities between different unique via patterns that leads to a seemingly qualitative differences in defectivity. The large available data volume enables further analysis to reliably distinguish global and local CDU variations, including a breakdown into local systematics and stochastics. A closer inspection of the tail end of the distributions and estimation of defect probabilities concludes that there is a common defect mechanism and defect threshold despite the observed differences of specific pattern characteristics. We expect that the analysis methodology can be applied for defect probability modeling as well as general process qualification in the future.

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; Yang, Yang; Ng, Tien Khee; Dursun, Ibrahim; Shi, Dong; Saidaminov, Makhsud I.; Priante, Davide; Bakr, Osman; Ooi, Boon S.

2015-01-01

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

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.

SKA aperture array verification system: electromagnetic modeling and beam pattern measurements using a micro UAV

Science.gov (United States)

de Lera Acedo, E.; Bolli, P.; Paonessa, F.; Virone, G.; Colin-Beltran, E.; Razavi-Ghods, N.; Aicardi, I.; Lingua, A.; Maschio, P.; Monari, J.; Naldi, G.; Piras, M.; Pupillo, G.

2018-03-01

In this paper we present the electromagnetic modeling and beam pattern measurements of a 16-elements ultra wideband sparse random test array for the low frequency instrument of the Square Kilometer Array telescope. We discuss the importance of a small array test platform for the development of technologies and techniques towards the final telescope, highlighting the most relevant aspects of its design. We also describe the electromagnetic simulations and modeling work as well as the embedded-element and array pattern measurements using an Unmanned Aerial Vehicle system. The latter are helpful both for the validation of the models and the design as well as for the future instrumental calibration of the telescope thanks to the stable, accurate and strong radio frequency signal transmitted by the UAV. At this stage of the design, these measurements have shown a general agreement between experimental results and numerical data and have revealed the localized effect of un-calibrated cable lengths in the inner side-lobes of the array pattern.

Study of molecular-beam epitaxy growth on patterned GaAs (311)A substrates with different mesa height

NARCIS (Netherlands)

Gong, Q.; Nötzel, R.; Schönherr, H.-P.; Ploog, K.

2000-01-01

We report on the evolution of the growth front during molecular-beam epitaxy on GaAs (3 1 1)A substrates stripe patterned along the [ ] direction as a function of the mesa height. During growth (1 0 0) and (2 1 1)A facets are formed and expand at the corners near the two opposite lying ( )A and (1 1

High-Performance Wireless via the Merger of CI Chip-Shaped DS-CDMA and Oscillating-Beam Smart Antenna Arrays

Directory of Open Access Journals (Sweden)

Nassar Carl R

2004-01-01

Full Text Available We introduce a novel merger of direct sequence code division multiple access (DS-CDMA and smart antenna arrays. With regard to the DS-CDMA scheme, we employ carrier interferometry DS-CDMA (CI/DS-CDMA, a novel implementation of DS-CDMA where chips are decomposable into narrowband frequency components. With regard to the antenna array, we deploy the oscillating-beam smart array. Here, applying proper time-varying phases to the array elements, we create small movement (oscillation in the antenna array's pattern, while steering the antenna pattern main lobe to the position of the intended user. The oscillating antenna pattern creates a time-varying channel with a controllable coherence time. This, in turn, provides transmit diversity in the form of a time diversity gain at the mobile receiver side. At the receiver, three stages of combining are available: combining time components of the received signal within symbol duration (each experiencing a different fade to enhance performance via time diversity; combining frequency components which make up the CI/DS-CDMA chip to enhance the performance via frequency diversity; and combining across chips to eliminate the interfering users on the system. Merging CI/DS-CDMA with the oscillating-beam smart antenna at the base station, we achieve very high capacity via the merger of SDMA (available through directionality of the antenna array and code division multiple access (inherent in CI/DS-CDMA, and very high performance via the construction of receivers that exploit both transmit diversity and frequency diversity. We present the performance gains of the proposed merger.

Influence of filling pattern structure on synchrotron radiation and beam spectrum at ANKA

Energy Technology Data Exchange (ETDEWEB)

Steinmann, Johannes; Brosi, Miriam; Bruendermann, Erik; Caselle, Michele; Blomley, Edmund; Hiller, Nicole; Kehrer, Benjamin; Mueller, Anke-Susanne; Schoenfeldt, Patrik; Schuh, Marcel; Schwarz, Markus; Siegel, Michael [Karlsruher Institut fuer Technologie, Karlsruhe (Germany)

2016-07-01

We present the effects of the filling pattern structure in multi-bunch mode on the beam spectrum. This effects can be seen by all detectors whose resolution is better than the RF frequency, ranging from stripline and Schottky measurements to high resolution synchrotron radiation measurements. Our heterodyne measurements of the emitted coherent synchrotron radiation at 270 GHz reveal the discrete frequency harmonics around the 100'000 revolution harmonic of ANKA, the synchrotron radiation facility in Karlsruhe, Germany. Significant effects of bunch spacing, gaps between bunch trains and variations in individual bunch currents on the emitted CSR spectrum are described by theory and supported by observations.

Radical External Beam Radiotherapy for Clinically Localized Prostate Cancer in Japan: Changing Trends in the Patterns of Care Process Survey

Energy Technology Data Exchange (ETDEWEB)

Ogawa, Kazuhiko, E-mail: kogawa@med.u-ryukyu.ac.jp [Department of Radiology, University of the Ryukyus, Okinawa (Japan); Nakamura, Katsumasa [Department of Clinical Radiology, Kyushu University Hospital at Beppu, Oita (Japan); Sasaki, Tomonari [Department of Radiation Oncology, National Kyushu Center, Fukuoka (Japan); Onishi, Hiroshi [Department of Radiology, Yamanashi University, Yamanashi (Japan); Koizumi, Masahiko [Department of Radiation Oncology, Osaka University, Osaka (Japan); Araya, Masayuki [Department of Radiology, Yamanashi University, Yamanashi (Japan); Mukumoto, Nobutaka; Teshima, Teruki [Department of Medical Physics and Engineering, Osaka University, Osaka (Japan); Mitsumori, Michihide [Department of Radiation Oncology and Image-Applied Therapy, Kyoto University, Kyoto (Japan)

2011-12-01

Purpose: To delineate changing trends in radical external beam radiotherapy (EBRT) for prostate cancer in Japan. Methods and Materials: Data from 841 patients with clinically localized prostate cancer treated with EBRT in the Japanese Patterns of Care Study (PCS) from 1996 to 2005 were analyzed. Results: Significant increases in the proportions of patients with stage T1 to T2 disease and decrease in prostate-specific antigen values were observed. Also, there were significant increases in the percentages of patients treated with radiotherapy by their own choice. Median radiation doses were 65.0 Gy and 68.4 Gy from 1996 to 1998 and from 1999 to 2001, respectively, increasing to 70 Gy from 2003 to 2005. Moreover, conformal therapy was more frequently used from 2003 to 2005 (84.9%) than from 1996 to 1998 (49.1%) and from 1999 to 2001 (50.2%). On the other hand, the percentage of patients receiving hormone therapy from 2003 to 2005 (81.1%) was almost the same as that from 1996 to 1998 (86.3%) and from 1999 to 2001 (89.7%). Compared with the PCS in the United States, patient characteristics and patterns of treatments from 2003 to 2005 have become more similar to those in the United States than those from 1996 to 1998 and those from 1999 to 2001. Conclusions: This study indicates a trend toward increasing numbers of patients with early-stage disease and increasing proportions of patients treated with higher radiation doses with advanced equipment among Japanese prostate cancer patients treated with EBRT during 1996 to 2005 survey periods. Patterns of care for prostate cancer in Japan are becoming more similar to those in the United States.

Convergent beam thickness determination of thin foil zirconium specimens

International Nuclear Information System (INIS)

Cann, C.D.

1978-07-01

The use of convergent beam patterns to determine the thickness of zirconium foils observed in the electron microscope has been investigated both theoretically and experimentally. On the basis of many-beam dynamical theory calculations, the [1012], [1013], and [1120] reflections at an accelerating voltage of 100 kV and the [1013], [1120], and [1122] reflections at 200 kV were found most suitable for convergent beam thickness determinations. Experimental convergent beam patterns were obtained in the JEOL-200B electron microscope under two different sets of conditions based on the size of the pattern desired. Computer assisted analysis of the patterns obtained gave foil thicknesses in good agreement with those determined from thickness extinction contours. (author)

Radiation regression patterns after cobalt plaque insertion for retinoblastoma

International Nuclear Information System (INIS)

Buys, R.J.; Abramson, D.H.; Ellsworth, R.M.; Haik, B.

1983-01-01

An analysis of 31 eyes of 30 patients who had been treated with cobalt plaques for retinoblastoma disclosed that a type I radiation regression pattern developed in 15 patients; type II, in one patient, and type III, in five patients. Nine patients had a regression pattern characterized by complete destruction of the tumor, the surrounding choroid, and all of the vessels in the area into which the plaque was inserted. This resulting white scar, corresponding to the sclerae only, was classified as a type IV radiation regression pattern. There was no evidence of tumor recurrence in patients with type IV regression patterns, with an average follow-up of 6.5 years, after receiving cobalt plaque therapy. Twenty-nine of these 30 patients had been unsuccessfully treated with at least one other modality (ie, light coagulation, cryotherapy, external beam radiation, or chemotherapy)

Radiation regression patterns after cobalt plaque insertion for retinoblastoma

Energy Technology Data Exchange (ETDEWEB)

Buys, R.J.; Abramson, D.H.; Ellsworth, R.M.; Haik, B.

1983-08-01

An analysis of 31 eyes of 30 patients who had been treated with cobalt plaques for retinoblastoma disclosed that a type I radiation regression pattern developed in 15 patients; type II, in one patient, and type III, in five patients. Nine patients had a regression pattern characterized by complete destruction of the tumor, the surrounding choroid, and all of the vessels in the area into which the plaque was inserted. This resulting white scar, corresponding to the sclerae only, was classified as a type IV radiation regression pattern. There was no evidence of tumor recurrence in patients with type IV regression patterns, with an average follow-up of 6.5 years, after receiving cobalt plaque therapy. Twenty-nine of these 30 patients had been unsuccessfully treated with at least one other modality (ie, light coagulation, cryotherapy, external beam radiation, or chemotherapy).

Integral dose investigation of non-coplanar treatment beam geometries in radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Dan; Dong, Peng; Ruan, Dan; Low, Daniel A.; Sheng, Ke, E-mail: ksheng@mednet.ucla.edu [Department of Radiation Oncology, University of California, Los Angeles, California 90095 (United States); Long, Troy; Romeijn, Edwin [Department of Industrial and Operations, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2014-01-15

Purpose: Automated planning and delivery of non-coplanar plans such as 4π radiotherapy involving a large number of fields have been developed to take advantage of the newly available automated couch and gantry on C-arm gantry linacs. However, there is an increasing concern regarding the potential changes in the integral dose that needs to be investigated. Methods: A digital torso phantom and 22 lung and liver stereotactic body radiation therapy (SBRT) patients were included in the study. The digital phantom was constructed as a water equivalent elliptical cylinder with a major axis length of 35.4 cm and minor axis of 23.6 cm. A 4.5 cm diameter target was positioned at varying depths along the major axis. Integral doses from intensity modulated, non-coplanar beams forming a conical pattern were compared against the equally spaced coplanar beam plans. Integral dose dependence on the phantom geometry and the beam number was also quantified. For the patient plans, the non-coplanar and coplanar beams and fluences were optimized using a column generation and pricing approach and compared against clinical VMAT plans using two full (lung) or partial coplanar arcs (liver) entering at the side proximal to the tumor. Both the average dose to the normal tissue volume and the total volumes receiving greater than 2 Gy (V2) and 5 Gy (V5) were evaluated and compared. Results: The ratio of integral dose from the non-coplanar and coplanar plans depended on the tumor depth for the phantom; for tumors shallower than 10 cm, the non-coplanar integral doses were lower than coplanar integral doses for non-coplanar angles less than 60°. Similar patterns were observed in the patient plans. The smallest non-coplanar integral doses were observed for tumor 6–8 cm deep. For the phantom, the integral dose was independent of the number of beams, consistent with the liver SBRT patients but the lung SBRT patients showed slight increase in the integral dose when more beams were used. Larger

Electron beam diagnostic system using computed tomography and an annular sensor

Science.gov (United States)

Elmer, John W.; Teruya, Alan T.

2014-07-29

A system for analyzing an electron beam including a circular electron beam diagnostic sensor adapted to receive the electron beam, the circular electron beam diagnostic sensor having a central axis; an annular sensor structure operatively connected to the circular electron beam diagnostic sensor, wherein the sensor structure receives the electron beam; a system for sweeping the electron beam radially outward from the central axis of the circular electron beam diagnostic sensor to the annular sensor structure wherein the electron beam is intercepted by the annular sensor structure; and a device for measuring the electron beam that is intercepted by the annular sensor structure.

Beam-beam interaction working group summary

International Nuclear Information System (INIS)

Siemann, R.H.

1995-01-01

The limit in hadron colliders is understood phenomenologically. The beam-beam interaction produces nonlinear resonances and makes the transverse tunes amplitude dependent. Tune spreads result from the latter, and as long as these tune spreads do not overlap low order resonances, the lifetime and performance is acceptable. Experience is that tenth and sometimes twelfth order resonances must be avoided, and the hadron collider limit corresponds roughly to the space available between resonances of that and lower order when operating near the coupling resonance. The beam-beam interaction in e + e - colliders is not understood well. This affects the performance of existing colliders and could lead to surprises in new ones. For example. a substantial amount of operator tuning is usually required to reach the performance limit given above, and this tuning has to be repeated after each major shutdown. The usual interpretation is that colliding beam performance is sensitive to small lattice errors, and these are being reduced during tuning. It is natural to ask what these errors are, how can a lattice be characterized to minimize tuning time, and what aspects of a lattice should receive particular attention when a new collider is being designed. The answers to this type of question are not known, and developing ideas for calculations, simulations and experiments that could illuminate the details of the beam-beam interaction was the primary working group activity

Comparison of Adsorbed Skin Dose Received by Patients in Cone Beam Computed Tomography, Spiral and Conventional Computed Tomography Scanninng

Directory of Open Access Journals (Sweden)

Rahimi A

2011-12-01

Full Text Available Background and Aims: The evaluation of absorbed dose received by patients could give useful information for radiation risk estimation. This study was performed to compare the entrance skin dose received by patients in cone beam computed tomography (CBCT, conventional and spiral computed tomography (CT.Materials and Methods: In this experimental study, 81 calibrated TLD chips were used. the TLD chips were placed on facial, thyroid and end of sternum skin surface in patients referred for CT of the paranasal sinuses(3 TLD chips for each area to estimate the absorbed dose received by central part of radiation field, thyroid and out of field areas, respectively. The data were analyzed using one-way ANOVA and Tukey tests. Results: The dose delivered to the center of irradiated field was about 0.79±0.09 mGy in CBCT technique compared with 16.31±3.71 and 18.84±4.12 mGy for spiral and conventional CT, respectively. The received dose by the out of field areas was about 54 percent of central area dose. There was statistical significant relationship between the imaging modalities and absorbed dose received by patients (P=0.016. The least absorbed dose was for CBCT and the greatest dose was for conventional CT imaging technique.Conclusion: The dose delivered to central area of irradiated field in conventional and spiral CT imaging modalities was about 24 times greater than of that in CBCT. Also, the highest received dose was for central area of radiated field and the lowest dose was for the out of field areas.

Lateral epitaxial overgrowth of GaN on a patterned GaN-on-silicon substrate by molecular beam epitaxy

International Nuclear Information System (INIS)

Wang, Yongjin; Hu, Fangren; Hane, Kazuhiro

2011-01-01

We report here the lateral epitaxial overgrowth (LEO) of GaN on a patterned GaN-on-silicon substrate by molecular beam epitaxy (MBE) growth with radio frequency nitrogen plasma as a gas source. Two kinds of GaN nanostructures are defined by electron beam lithography and realized on a GaN substrate by fast atom beam etching. The epitaxial growth of GaN by MBE is performed on the prepared GaN template, and the selective growth of GaN takes place with the assistance of GaN nanostructures. The LEO of GaN produces novel GaN epitaxial structures which are dependent on the shape and the size of the processed GaN nanostructures. Periodic GaN hexagonal pyramids are generated inside the air holes, and GaN epitaxial strips with triangular section are formed in the grating region. This work provides a promising way for producing novel GaN-based devices by the LEO of GaN using the MBE technique

Micro-patterns fabrication using focused proton beam lithography

Energy Technology Data Exchange (ETDEWEB)

Cutroneo, M., E-mail: cutroneo@ujf.cas.cz [Nuclear Physics Institute, AS CR, 25068 Rez (Czech Republic); Havranek, V. [Nuclear Physics Institute, AS CR, 25068 Rez (Czech Republic); Mackova, A. [Nuclear Physics Institute, AS CR, 25068 Rez (Czech Republic); Department of Physics, Faculty of Science, J.E. Purkinje University, Ceske mladeze 8, 400 96 Usti nad Labem (Czech Republic); Semian, V. [Nuclear Physics Institute, AS CR, 25068 Rez (Czech Republic); Torrisi, L. [Department of Physics and Earth Sciences, Messina University, V.le F.S. d’Alcontres 31, 98166 S. Agata, Messina (Italy); Calcagno, L. [Department of Physics, Catania University, V. S. Sofia 64, 95123 Catania (Italy)

2016-03-15

Proton beam writing technique was recently introduced at 3MV Tandetron accelerator at Nuclear Physics Institute in Rez (Czech Republic). It has been used, to produce three-dimensional (3D) micro-structures in poly(methylmethacrylate) by 2.0 MeV and 2.6 MeV protons micro-beam. Micro-channels (52 μm × 52 μm) have been realized. After chemical etching, the quality of the bottom and side walls of the produced structures in PMMA were analyzed using Scanning Transmission Ion Microscopy (STIM).

Methods and Devices for Space Optical Communications Using Laser Beams

Science.gov (United States)

Goorjian, Peter M. (Inventor)

2018-01-01

Light is used to communicate between objects separated by a large distance. Light beams are received in a telescopic lens assembly positioned in front of a cat's-eye lens. The light can thereby be received at various angles to be output by the cat's-eye lens to a focal plane of the cat's-eye lens, the position of the light beams upon the focal plane corresponding to the angle of the beam received. Lasers and photodetectors are distributed along this focal plane. A processor receives signals from the photodetectors, and selectively signal lasers positioned proximate the photodetectors detecting light, in order to transmit light encoding data through the cat's-eye lens and also through a telescopic lens back in the direction of the received light beams, which direction corresponds to a location upon the focal plane of the transmitting lasers.

HIGH-EFFICIENCY INFRARED RECEIVER

Directory of Open Access Journals (Sweden)

A. K. Esman

2016-01-01

Full Text Available Recent research and development show promising use of high-performance solid-state receivers of the electromagnetic radiation. These receivers are based on the low-barrier Schottky diodes. The approach to the design of the receivers on the basis of delta-doped low-barrier Schottky diodes with beam leads without bias is especially actively developing because for uncooled receivers of the microwave radiation these diodes have virtually no competition. The purpose of this work is to improve the main parameters and characteristics that determine the practical relevance of the receivers of mid-infrared electromagnetic radiation at the operating room temperature by modifying the electrodes configuration of the diode and optimizing the distance between them. Proposed original design solution of the integrated receiver of mid-infrared radiation on the basis of the low-barrier Schottky diodes with beam leads allows to effectively adjust its main parameters and characteristics. Simulation of the electromagnetic characteristics of the proposed receiver by using the software package HFSS with the basic algorithm of a finite element method which implemented to calculate the behavior of electromagnetic fields on an arbitrary geometry with a predetermined material properties have shown that when the inner parts of the electrodes of the low-barrier Schottky diode is performed in the concentric elliptical convex-concave shape, it can be reduce the reflection losses to -57.75 dB and the standing wave ratio to 1.003 while increasing the directivity up to 23 at a wavelength of 6.09 μm. At this time, the rounded radii of the inner parts of the anode and cathode electrodes are equal 212 nm and 318 nm respectively and the gap setting between them is 106 nm. These parameters will improve the efficiency of the developed infrared optical-promising and electronic equipment for various purposes intended for work in the mid-infrared wavelength range. 

Propagation of rotational Risley-prism-array-based Gaussian beams in turbulent atmosphere

Science.gov (United States)

Chen, Feng; Ma, Haotong; Dong, Li; Ren, Ge; Qi, Bo; Tan, Yufeng

2018-03-01

Limited by the size and weight of prism and optical assembling, Rotational Risley-prism-array system is a simple but effective way to realize high power and superior beam quality of deflecting laser output. In this paper, the propagation of the rotational Risley-prism-array-based Gaussian beam array in atmospheric turbulence is studied in detail. An analytical expression for the average intensity distribution at the receiving plane is derived based on nonparaxial ray tracing method and extended Huygens-Fresnel principle. Power in the diffraction-limited bucket is chosen to evaluate beam quality. The effect of deviation angle, propagation distance and intensity of turbulence on beam quality is studied in detail by quantitative simulation. It reveals that with the propagation distance increasing, the intensity distribution gradually evolves from multiple-petal-like shape into the pattern that contains one main-lobe in the center with multiple side-lobes in weak turbulence. The beam quality of rotational Risley-prism-array-based Gaussian beam array with lower deviation angle is better than its counterpart with higher deviation angle when propagating in weak and medium turbulent (i.e. Cn2 beam quality of higher deviation angle arrays degrades faster as the intensity of turbulence gets stronger. In the case of propagating in strong turbulence, the long propagation distance (i.e. z > 10km ) and deviation angle have no influence on beam quality.

Solar Power Beaming: From Space to Earth

Energy Technology Data Exchange (ETDEWEB)

Rubenchik, A M; Parker, J M; Beach, R J; Yamamoto, R M

2009-04-14

Harvesting solar energy in space and power beaming the collected energy to a receiver station on Earth is a very attractive way to help solve mankind's current energy and environmental problems. However, the colossal and expensive 'first step' required in achieving this goal has to-date stifled its initiation. In this paper, we will demonstrate that recent advance advances in laser and optical technology now make it possible to deploy a space-based system capable of delivering 1 MW of energy to a terrestrial receiver station, via a single unmanned commercial launch into Low Earth Orbit (LEO). Figure 1 depicts the overall concept of our solar power beaming system, showing a large solar collector in space, beaming a coherent laser beam to a receiving station on Earth. We will describe all major subsystems and provide technical and economic discussion to support our conclusions.

Maskless, resistless ion beam lithography

International Nuclear Information System (INIS)

Ji, Qing

2003-01-01

As the dimensions of semiconductor devices are scaled down, in order to achieve higher levels of integration, optical lithography will no longer be sufficient for the needs of the semiconductor industry. Alternative next-generation lithography (NGL) approaches, such as extreme ultra-violet (EUV), X-ray, electron-beam, and ion projection lithography face some challenging issues with complicated mask technology and low throughput. Among the four major alternative NGL approaches, ion beam lithography is the only one that can provide both maskless and resistless patterning. As such, it can potentially make nano-fabrication much simpler. This thesis investigates a focused ion beam system for maskless, resistless patterning that can be made practical for high-volume production. In order to achieve maskless, resistless patterning, the ion source must be able to produce a variety of ion species. The compact FIB system being developed uses a multicusp plasma ion source, which can generate ion beams of various elements, such as O 2 + , BF 2 + , P + etc., for surface modification and doping applications. With optimized source condition, around 85% of BF 2 + , over 90% of O 2 + and P + have been achieved. The brightness of the multicusp-plasma ion source is a key issue for its application to maskless ion beam lithography. It can be substantially improved by optimizing the source configuration and extractor geometry. Measured brightness of 2 keV He + beam is as high as 440 A/cm 2 · Sr, which represents a 30x improvement over prior work. Direct patterning of Si thin film using a focused O 2 + ion beam has been investigated. A thin surface oxide film can be selectively formed using 3 keV O 2 + ions with the dose of 10 15 cm -2 . The oxide can then serve as a hard mask for patterning of the Si film. The process flow and the experimental results for directly patterned poly-Si features are presented. The formation of shallow pn-junctions in bulk silicon wafers by scanning focused P

Dual-beam CRT

International Nuclear Information System (INIS)

1975-01-01

A dual-beam cathode-ray tube having a pair of electron guns and associated deflection means disposed side-by-side on each side of a central axis is described. The electron guns are parallel and the deflection means includes beam centering plates and angled horizontal deflection plates to direct the electron beams toward the central axis, precluding the need for a large-diameter tube neck in which the entire gun structures are angled. Bowing control plates are disposed adjacent to the beam centering plates to minimize trace bowing, and an intergun shield is disposed between the horizontal deflection plates to control and correct display pattern geometry distortion

Memory resistive switching in CeO{sub 2}-based film microstructures patterned by a focused ion beam

Energy Technology Data Exchange (ETDEWEB)

Velichko, A. [Petrozavodsk State University, 185910 Petrozavodsk (Russian Federation); Boriskov, P., E-mail: boriskov@psu.karelia.ru [Petrozavodsk State University, 185910 Petrozavodsk (Russian Federation); Savenko, A. [Petrozavodsk State University, 185910 Petrozavodsk (Russian Federation); Grishin, A.; Khartsev, S.; Yar, M. Ahmed; Muhammed, M. [Royal Institute of Technology, SE-164 40 Stockholm, Kista (Sweden)

2014-04-01

Heteroepitaxial CeO{sub 2} (80 nm)/La{sub 0.5}Sr{sub 0.5}CoO{sub 3} (500 nm) film structure has been pulsed laser deposited on a sapphire substrate. The Ag/CeO{sub 2} microjunctions patterned by a focused ion beam on a La{sub 0.5}Sr{sub 0.5}CoO{sub 3} film exhibit reproducible reversible switching between a high resistance state (OFF) with insulating properties and a semiconducting or metallic low resistance state (ON) with resistance ratios up to 10{sup 4}. 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 of the electrical forming, responsible for the memory effect, has been proved, along with a mechanism of a self-healing electrical breakdown. - Highlights: • Ag/CeO{sub 2}/La{sub 0.5}Sr{sub 0.5}CoO{sub 3} microstructures were patterned by a focused ion beam. • Reproducible memory resistive switching was discovered in Ag/CeO{sub 2} microjunctions. • Micro-scaling affects electrical characteristics of Ag/CeO{sub 2} microjunctions. • A mechanism of a self-healing breakdown was discovered.

Overview of LHC Beam Loss Measurements

CERN Document Server

Dehning, B; Effinger, E; Emery, J; Fadakis, E; Holzer, E B; Jackson, S; Kruk, G; Kurfuerst, C; Marsili, A; Misiowiec, M; Nebot Del Busto, E; Nordt, A; Priebe, A; Roderick, C; Sapinski, M; Zamantzas, C; Grishin, V; Griesmayer, E

2011-01-01

The LHC beam loss monitoring system provides measurements with an update rate of 1 Hz and high time resolution data by event triggering. These informations are used for the initiation of beam aborts, fixed displays and the off line analysis. The analysis of fast and localized loss events resulted in the determination of its rate, duration, peak amplitudes, its scaling with intensity, number of bunches and beam energy. The calibration of the secondary shower beam loss signal in respect to the needed beam energy deposition to quench the magnet coil is addressed at 450GeV and 3.5T eV . The adjustment of collimators is checked my measuring the loss pattern and its variation in the collimation regions of the LHC. Loss pattern changes during a fill allow the observation of non typical fill parameters.

Initial alignment method for free space optics laser beam

Science.gov (United States)

Shimada, Yuta; Tashiro, Yuki; Izumi, Kiyotaka; Yoshida, Koichi; Tsujimura, Takeshi

2016-08-01

The authors have newly proposed and constructed an active free space optics transmission system. It is equipped with a motor driven laser emitting mechanism and positioning photodiodes, and it transmits a collimated thin laser beam and accurately steers the laser beam direction. It is necessary to introduce the laser beam within sensible range of the receiver in advance of laser beam tracking control. This paper studies an estimation method of laser reaching point for initial laser beam alignment. Distributed photodiodes detect laser luminescence at respective position, and the optical axis of laser beam is analytically presumed based on the Gaussian beam optics. Computer simulation evaluates the accuracy of the proposed estimation methods, and results disclose that the methods help us to guide the laser beam to a distant receiver.

Longitudinal Beam measurements at the LHC: The LHC Beam Quality Monitor

CERN Document Server

Papotti, G; Follin, F; Wehrle, U

2011-01-01

The LHC Beam Quality Monitor is a system that measures individual bunch lengths and positions, similarly to the twin system SPS Beam Quality Monitor, from which it was derived. The pattern verification that the system provides is vital during the injection process to verify the correctness of the injected pattern, while the bunch length measurement is fed back to control the longitudinal emittance blow up performed during the energy ramp and provides a general indication of the health of the RF system. The algorithms used, the hardware implementation and the system integration in the LHC control infrastructure are presented in this paper, along with possible improvements.

NSLS-II filling pattern measurement

International Nuclear Information System (INIS)

Yong Hu; Dalesio, L.B.; Kiman Ha; Pinayev, I.

2012-01-01

Multi-bunch injection will be deployed at NSLS-II. High bandwidth diagnostic beam monitors with high speed digitizers are used to measure bunch-by-bunch charge variation. In order to minimize intensity-correlated orbit oscillations due to uneven bunch patterns, we need to measure the filling pattern (also named bunch pattern or bunch structure). This paper focuses on filling pattern measurements: how to measure bunch structure and make this information available in EPICS-based control system. This measurement requires combination of 3 types of beam monitors (Wall Current Monitor, Fast Current Transformer and Beam Position Monitor), data acquisition and controls (fast digitizer, EPICS software, etc.) and Event Timing system. High-bandwidth filling pattern monitor requires high-speed digitizer to sample its analog output signal. The evaluation results of commercial fast digitizer Agilent Acqiris and high bandwidth detector Bergoz FCT are presented. We have also tested the algorithm software for filling pattern measurement as well as the interface to event timing system. It appears that filling pattern measurement system is well understood and the tests for control hardware and software have given good results

WORKSHOP: Crystalline beams

International Nuclear Information System (INIS)

Anon.

1989-01-01

Following pioneer work by specialists at the Soviet Novosibirsk Laboratory some ten years ago, interest developed in the possibility of 'freezing' ion beams in storage rings by pushing cooling (to smooth out beam behaviour) to its limits, the final goal being to lock the ions into a neat crystal pattern. After advances by groups working on laser cooled ions in traps, and with several cooling rings now in operation, a workshop on crystalline ion beams was organized recently by the GSI (Darmstadt) Laboratory and held at Wertheim in Germany

Broad-band beam buncher

International Nuclear Information System (INIS)

Goldberg, D.A.; Flood, W.S.; Arthur, A.A.; Voelker, F.

1986-01-01

This patent describes a broad-band beam buncher. This beam buncher consists of: a housing adapted to be eacuated, an electron gun in the housing for producing a beam of electrons, buncher means in the housing forming a buncher cavity which has an entrance opening for receiving the electron beam and an exit opening through which the electron beam passes out of the buncher cavity, a drift tube electrode in the buncher cavity and disposed between the entrance opening and the exit opening with first and second gaps between the drift tube electrode and the entrance and exit openings, the drift tube electrode which has a first drift space through which the electron beam passes in traveling between the entrance and exit openings, modulating means for supplying an ultrahigh frequeny modulating signal to the drift tube electrode for producing velocity modulation of the electrons in the electron beam as the electrons pass through the buncher cavity and the drift tube electrode between the entrance opening and the exit opening, drift space means in the housing forming a second drift space for receiving the velocity modulated electron beam from the exit opening, the velocity modulated electron beam being bunched as it passes along the second drift space, the drift space means has a discharge opening through which the electron beam is discharged from the second drift space after being bunched therein, the modulating means containing a signal source for producing an ultrahigh frequency signal, a transmission line connected between the signal source and the drift tube electrode, and terminating means connected to the drift tube electrode for terminating the transmission line in approximately its characteristic impedance to afford a broad response band with minimum 6 variations therein

Ion beams in materials processing and analysis

CERN Document Server

Schmidt, Bernd

2012-01-01

This book covers ion beam application in modern materials research, offering the basics of ion beam physics and technology and a detailed account of the physics of ion-solid interactions for ion implantation, ion beam synthesis, sputtering and nano-patterning.

Development and characterization of micro-pattern gas detectors for intense beams of hadrons

Energy Technology Data Exchange (ETDEWEB)

Vandenbroucke, Maxence

2012-07-02

This thesis work is dedicated to the design, development and characterization of Micro-Pattern Gas Detectors. The performances of a Time Projection Chamber (TPC) equipped with a triple Gas Electron Multiplier (GEM) amplification structure are reported. The intrinsic ion backflow suppression of GEM foils drastically reduces the space charge produced by wire readout in traditional TPC. The GEM solution allows the operation of a TPC at much higher event rate. The second part of this thesis describes the development of a 40 x 40 cm{sup 2} Micromegas detector with a highly segmented central area. A reduction of discharges compared to conventional Micromegas detectors is needed for stable operation in intense beams of hadrons. Spark reduction technologies have been successfully studied and results are presented.

Development and characterization of micro-pattern gas detectors for intense beams of hadrons

International Nuclear Information System (INIS)

Vandenbroucke, Maxence

2012-01-01

This thesis work is dedicated to the design, development and characterization of Micro-Pattern Gas Detectors. The performances of a Time Projection Chamber (TPC) equipped with a triple Gas Electron Multiplier (GEM) amplification structure are reported. The intrinsic ion backflow suppression of GEM foils drastically reduces the space charge produced by wire readout in traditional TPC. The GEM solution allows the operation of a TPC at much higher event rate. The second part of this thesis describes the development of a 40 x 40 cm 2 Micromegas detector with a highly segmented central area. A reduction of discharges compared to conventional Micromegas detectors is needed for stable operation in intense beams of hadrons. Spark reduction technologies have been successfully studied and results are presented.

Three-dimensional evaluation of pharyngeal airway in individuals with varying growth patterns using cone beam computed tomography

OpenAIRE

Rohan Diwakar; Maninder Singh Sidhu; Mona Prabhakar; Seema Grover; Ritu Phogat

2015-01-01

Introduction: The purpose of this study was to evaluate the pharyngeal airway volume in individuals with different vertical growth patterns. Methods: Cone beam computed tomography scans were evaluated of 40 subjects with the age range from 14 to 25 years and were divided into three groups. Horizontal growers consisted of 13 subjects, normal growers consisted of 14 subjects, and the vertical growers consisted of 13 subjects. The pharyngeal airway volume was measured using In Vivo Dental 5.1 so...

Maskless, resistless ion beam lithography

Energy Technology Data Exchange (ETDEWEB)

Ji, Qing [Univ. of California, Berkeley, CA (United States)

2003-01-01

As the dimensions of semiconductor devices are scaled down, in order to achieve higher levels of integration, optical lithography will no longer be sufficient for the needs of the semiconductor industry. Alternative next-generation lithography (NGL) approaches, such as extreme ultra-violet (EUV), X-ray, electron-beam, and ion projection lithography face some challenging issues with complicated mask technology and low throughput. Among the four major alternative NGL approaches, ion beam lithography is the only one that can provide both maskless and resistless patterning. As such, it can potentially make nano-fabrication much simpler. This thesis investigates a focused ion beam system for maskless, resistless patterning that can be made practical for high-volume production. In order to achieve maskless, resistless patterning, the ion source must be able to produce a variety of ion species. The compact FIB system being developed uses a multicusp plasma ion source, which can generate ion beams of various elements, such as O₂⁺, BF₂⁺, P⁺ etc., for surface modification and doping applications. With optimized source condition, around 85% of BF₂⁺, over 90% of O₂⁺ and P⁺ have been achieved. The brightness of the multicusp-plasma ion source is a key issue for its application to maskless ion beam lithography. It can be substantially improved by optimizing the source configuration and extractor geometry. Measured brightness of 2 keV He⁺ beam is as high as 440 A/cm² • Sr, which represents a 30x improvement over prior work. Direct patterning of Si thin film using a focused O₂⁺ ion beam has been investigated. A thin surface oxide film can be selectively formed using 3 keV O₂⁺ ions with the dose of 10¹⁵ cm^-2. The oxide can then serve as a hard mask for patterning of the Si film. The

Patterning of nanoparticulate transparent conductive ITO films using UV light irradiation and UV laser beam writing

International Nuclear Information System (INIS)

Solieman, A.; Moharram, A.H.; Aegerter, M.A.

2010-01-01

Indium tin oxide (ITO) thin film is one of the most widely used as transparent conductive electrodes in all forms of flat panel display (FPD) and microelectronic devices. Suspension of already crystalline conductive ITO nanoparticles fully dispersed in alcohol was spun, after modifying with coupling agent, on glass substrates. The low cost, simple and versatile traditional photolithography process without complication of the photoresist layer was used for patterning ITO films. Using of UV light irradiation through mask and direct UV laser beam writing resulted in an accurate linear, sharp edge and very smooth patterns. Irradiated ITO film showed a high transparency (∼85%) in the visible region. The electrical sheet resistance decrease with increasing time of exposure to UV light and UV laser. Only 5 min UV light irradiation is enough to decrease the electrical sheet resistance down to 5 kΩ□.

Self-tracking optical beam monitor

International Nuclear Information System (INIS)

Miyahara, T.; Mitsuhashi, T.

1992-01-01

A new optical beam monitor with a self-tracking system was constructed and tested at an undulator beam line of the Photon Factory. The monitor has a feedback system to receive a constant part of the radiation and gives a large range of linearity. The beam position is read out through a linear encoder to detect the self-tracking movement of a pair of photocathodes. The monitor except the feedback system is totally bakeable and UHV compatible and can be installed at a VUV or a soft x-ray beam line

Prescription Pattern of Analgesic Drugs for Patients Receiving Palliative Care in a Teaching Hospital in India.

Science.gov (United States)

Menezes, Vishma Hydie; Nair, Shoba N; Soumya, M S; Tarey, S D

2016-01-01

Drugs used in the palliative care unit for managing symptoms are major contributors toward the expenditure occurring in palliative care. This study was conducted to understand the prescription pattern of analgesic drugs in the patients who are receiving palliative care in a teaching hospital in India by a retrospective study of case records. Case record based, retrospective, descriptive study was conducted at the Pain and Palliative Care Department of St. John's Medical College Hospital, Bengaluru. Case record files of all patients referred to Pain and Palliative Care Department for the treatment of pain in the year of 2012 were studied. Patients' age, gender, diagnoses, numerical pain rating scale (0-10), drugs prescribed, dosage, frequency, route of administration were recorded. The difference in drug utilization between the genders was done using Chi-square test. Data were collected from 502 patients of which 280 (56%) were males and 222 (44%) were females. Twelve percent of patients had mild pain (1-3), 34% had moderate pain (4-6), and 54% had severe pain (7-10). The most commonly used analgesic drugs were opioids (47%), followed by nonsteroidal anti-inflammatory drugs (36%). The opioids used were tramadol (56%), and morphine (38%). Ninety percent of patients with numerical pain scale more than 6 received morphine. There was no difference in analgesic drug utilization with regards to gender. Prescription pattern differed depending on the severity of pain. Opioids were the most commonly used drugs for pain management. The study shows that prescription pattern in palliative care unit of this hospital was in accordance with WHO pain management guidelines. The study showed the current trend in prescription of analgesic drugs in the teaching hospital where the study was conducted.

Massively parallel E-beam inspection: enabling next-generation patterned defect inspection for wafer and mask manufacturing

Science.gov (United States)

Malloy, Matt; Thiel, Brad; Bunday, Benjamin D.; Wurm, Stefan; Mukhtar, Maseeh; Quoi, Kathy; Kemen, Thomas; Zeidler, Dirk; Eberle, Anna Lena; Garbowski, Tomasz; Dellemann, Gregor; Peters, Jan Hendrik

2015-03-01

SEMATECH aims to identify and enable disruptive technologies to meet the ever-increasing demands of semiconductor high volume manufacturing (HVM). As such, a program was initiated in 2012 focused on high-speed e-beam defect inspection as a complement, and eventual successor, to bright field optical patterned defect inspection [1]. The primary goal is to enable a new technology to overcome the key gaps that are limiting modern day inspection in the fab; primarily, throughput and sensitivity to detect ultra-small critical defects. The program specifically targets revolutionary solutions based on massively parallel e-beam technologies, as opposed to incremental improvements to existing e-beam and optical inspection platforms. Wafer inspection is the primary target, but attention is also being paid to next generation mask inspection. During the first phase of the multi-year program multiple technologies were reviewed, a down-selection was made to the top candidates, and evaluations began on proof of concept systems. A champion technology has been selected and as of late 2014 the program has begun to move into the core technology maturation phase in order to enable eventual commercialization of an HVM system. Performance data from early proof of concept systems will be shown along with roadmaps to achieving HVM performance. SEMATECH's vision for moving from early-stage development to commercialization will be shown, including plans for development with industry leading technology providers.

Beam dancer fusion device

International Nuclear Information System (INIS)

Maier, H.B.

1984-01-01

To accomplish fusion of two or more fusion fuel elements numerous minute spots of energy or laser light are directed to a micro target area, there to be moved or danced about by a precision mechanical controlling apparatus at the source of the laser light or electromagnetic energy beams, so that merging and coinciding patterns of light or energy beams can occur around the area of the fuel atoms or ions. The projecting of these merging patterns may be considered as target searching techniques to locate responsive clusters of fuel elements and to compress such elements into a condition in which fusion may occur. Computerized programming may be used

Beam halo formation from space-charge dominated beams in uniform focusing channels

International Nuclear Information System (INIS)

O'Connell, J.S.; Wangler, T.P.; Mills, R.S.; Crandall, K.R.

1993-01-01

In space-charge dominated beams the nonlinear space-charge forces produce a filamentation pattern, which results in a 2-component beam consisting of an inner core and an outer halo. The halo is very prominent in mismatched beams, and the potential for accelerator activation is of concern for a next generation of cw, high-power proton linacs that could be applied for intense neutron generators to process nuclear materials. We present new results about beam halo and the evolution of space-charge dominated beams from multiparticle simulation of initial laminar beams in a uniform linear focusing channel, and from a model consisting of single particle interactions with a uniform-density beam core. We study the energy gain from particle interactions with the space-charge field of the core, and we identify the resonant characteristic of this interaction as the basic cause of the separation of the beam into the two components. We identify three different particle-trajectory types, and we suggest that one of these types may lead to continuous halo growth, even after the halo is removed by collimators

External Beam Radiation Therapy for Cancer

Science.gov (United States)

External beam radiation therapy is used to treat many types of cancer. it is a local treatment, where a machine aims radiation at your cancer. Learn more about different types of external beam radiation therapy, and what to expect if you're receiving treatment.

Electron beam patterning for writing of positively charged gold colloidal nanoparticles

Science.gov (United States)

Zafri, Hadar; Azougi, Jonathan; Girshevitz, Olga; Zalevsky, Zeev; Zitoun, David

2018-02-01

Synthesis at the nanoscale has progressed at a very fast pace during the last decades. The main challenge today lies in precise localization to achieve efficient nanofabrication of devices. In the present work, we report on a novel method for the patterning of gold metallic nanoparticles into nanostructures on a silicon-on-insulator (SOI) wafer. The fabrication makes use of relatively accessible equipment, a scanning electron microscope (SEM), and wet chemical synthesis. The electron beam implants electrons into the insulating material, which further anchors the positively charged Au nanoparticles by electrostatic attraction. The novel fabrication method was applied to several substrates useful in microelectronics to add plasmonic particles. The resolution and surface density of the deposition were tuned, respectively, by the electron energy (acceleration voltage) and the dose of electronic irradiation. We easily achieved the smallest written feature of 68 ± 18 nm on SOI, and the technique can be extended to any positively charged nanoparticles, while the resolution is in principle limited by the particle size distribution and the scattering of the electrons in the substrate. [Figure not available: see fulltext.

NETWORK CODING BY BEAM FORMING

DEFF Research Database (Denmark)

2013-01-01

Network coding by beam forming in networks, for example, in single frequency networks, can provide aid in increasing spectral efficiency. When network coding by beam forming and user cooperation are combined, spectral efficiency gains may be achieved. According to certain embodiments, a method...... cooperating with the plurality of user equipment to decode the received data....

Design Study for Pulsed Proton Beam Generation

Directory of Open Access Journals (Sweden)

Han-Sung Kim

2016-02-01

Full Text Available Fast neutrons with a broad energy spectrum, with which it is possible to evaluate nuclear data for various research fields such as medical applications and the development of fusion reactors, can be generated by irradiating proton beams on target materials such as beryllium. To generate short-pulse proton beam, we adopted a deflector and slit system. In a simple deflector with slit system, most of the proton beam is blocked by the slit, especially when the beam pulse width is short. Therefore, the available beam current is very low, which results in low neutron flux. In this study, we proposed beam modulation using a buncher cavity to increase the available beam current. The ideal field pattern for the buncher cavity is sawtooth. To make the field pattern similar to a sawtooth waveform, a multiharmonic buncher was adopted. The design process for the multiharmonic buncher includes a beam dynamics calculation and three-dimensional electromagnetic simulation. In addition to the system design for pulsed proton generation, a test bench with a microwave ion source is under preparation to test the performance of the system. The design study results concerning the pulsed proton beam generation and the test bench preparation with some preliminary test results are presented in this paper.

Applications of power beaming from space-based nuclear power stations. [Laser beaming to airplanes; microwave beaming to ground

Energy Technology Data Exchange (ETDEWEB)

Powell, J.R.; Botts, T.E.; Hertzberg, A.

1981-01-01

Power beaming from space-based reactor systems is examined using an advanced compact, lightweight Rotating Bed Reactor (RBR). Closed Brayton power conversion efficiencies in the range of 30 to 40% can be achieved with turbines, with reactor exit temperatures on the order of 2000/sup 0/K and a liquid drop radiator to reject heat at temperatures of approx. 500/sup 0/K. Higher RBR coolant temperatures (up to approx. 3000/sup 0/K) are possible, but gains in power conversion efficiency are minimal, due to lower expander efficiency (e.g., a MHD generator). Two power beaming applications are examined - laser beaming to airplanes and microwave beaming to fixed ground receivers. Use of the RBR greatly reduces system weight and cost, as compared to solar power sources. Payback times are a few years at present prices for power and airplane fuel.

Cell patterning on poly(sodium 4-styrenesulfonate)-patterned fluoropolymer substrate

Energy Technology Data Exchange (ETDEWEB)

Kim, Wan-Joong [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of); Department of Polymer Science and Engineering, Chungnam National University, Yuseong-gu, Daejeon 305-764 (Korea, Republic of); Jung, Chang-Hee; Hwang, In-Tae [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of); Jung, Chan-Hee, E-mail: jch@kaeri.re.kr [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of); Choi, Jae-Hak, E-mail: jaehakchoi@cnu.ac.kr [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of); Department of Polymer Science and Engineering, Chungnam National University, Yuseong-gu, Daejeon 305-764 (Korea, Republic of); Hong, Sung-Kwon [Department of Polymer Science and Engineering, Chungnam National University, Yuseong-gu, Daejeon 305-764 (Korea, Republic of)

2013-10-15

Highlights: •PFA films were functionalized by ion-beam induced surface graft polymerization. •Poly(sodium 4-styrenesulfonate) (PSS)-patterned PFA films were prepared. •Well-organized cell patterns were obtained on PSS-patterned PFA films. •This method is useful to fabricate bio-platforms for cell-based biodevices. -- Abstract: The surface functionalization of bio-inert fluoropolymer films through ion beam-induced surface graft polymerization was investigated to control the cellular behavior. The surface of poly(tetrafluoroethylene-co-perfluoropropl vinyl ether) (PFA) films was selectively activated by 150 keV H{sup +} ion implantation in the presence of a pattern mask and sodium 4-styrenesulfonate (SS) was then graft polymerized onto the implanted PFA films to form hydrophilic poly(sodium 4-styrenesulfonate) (PSS)-patterned PFA films. The surface of the resulting PSS-patterned PFA films was investigated in terms of the degree of graft polymerization, chemical structure, chemical composition, wettability, and morphology. The analytical results revealed that PSS was selectively grafted onto the implanted regions of the PFA films. Furthermore, in vitro cell culture on the PSS-patterned PFA films exhibited a preferential adhesion and growth of cells onto the PSS-grafted regions, resulting in well-organized 100 μm cell patterns.

Cell patterning on poly(sodium 4-styrenesulfonate)-patterned fluoropolymer substrate

International Nuclear Information System (INIS)

Kim, Wan-Joong; Jung, Chang-Hee; Hwang, In-Tae; Jung, Chan-Hee; Choi, Jae-Hak; Hong, Sung-Kwon

2013-01-01

Highlights: •PFA films were functionalized by ion-beam induced surface graft polymerization. •Poly(sodium 4-styrenesulfonate) (PSS)-patterned PFA films were prepared. •Well-organized cell patterns were obtained on PSS-patterned PFA films. •This method is useful to fabricate bio-platforms for cell-based biodevices. -- Abstract: The surface functionalization of bio-inert fluoropolymer films through ion beam-induced surface graft polymerization was investigated to control the cellular behavior. The surface of poly(tetrafluoroethylene-co-perfluoropropl vinyl ether) (PFA) films was selectively activated by 150 keV H + ion implantation in the presence of a pattern mask and sodium 4-styrenesulfonate (SS) was then graft polymerized onto the implanted PFA films to form hydrophilic poly(sodium 4-styrenesulfonate) (PSS)-patterned PFA films. The surface of the resulting PSS-patterned PFA films was investigated in terms of the degree of graft polymerization, chemical structure, chemical composition, wettability, and morphology. The analytical results revealed that PSS was selectively grafted onto the implanted regions of the PFA films. Furthermore, in vitro cell culture on the PSS-patterned PFA films exhibited a preferential adhesion and growth of cells onto the PSS-grafted regions, resulting in well-organized 100 μm cell patterns

Identification of LHC beam loss mechanism : a deterministic treatment of loss patterns

CERN Document Server

Marsili, Aurélien

CERN's Large Hadron Collider (LHC) is the largest machine ever built, with a total circumference of 26.7 km; and it is the most powerful accelerator ever, both in beam energy and beam intensity. The main magnets are superconducting, keeping the particles into two counter circulating beams, which collide in four interaction points. CERN and the LHC will be described in chap. 1. The superconducting magnets of the LHC have to be protected against particle losses. Depending on the number of lost particles, the coils of the magnets will become normal conducting and/or will be damaged. To avoid these events a beam loss monitoring (BLM) system was installed to measure the particle loss rates. If the predefined safe thresholds of loss rates are exceeded, the beams are directed out of the accelerator ring towards the beam dump. The detectors of the BLM system are mainly ionization chambers located outside of the cryostats. In total, about 3500 ionisation chambers are installed. Further challenges include the high dyna...

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

Stress evaluation in thin films: Micro-focus synchrotron X-ray diffraction combined with focused ion beam patterning for d{sub o} evaluation

Energy Technology Data Exchange (ETDEWEB)

Baimpas, Nikolaos, E-mail: nikolaos.baimpas@eng.ox.ac.uk [University of Oxford, Dept. of Engineering Science (United Kingdom); Le Bourhis, Eric [University of Poitiers, Institut P' , Laboratoire de Physique des Matériaux, Poitiers (France); Eve, Sophie [ENSICAEN, CRISMAT, Caen (France); Thiaudière, Dominique [Synchrotron SOLEIL, L' Orme des Merisiers Saint-Aubin, Paris (France); Hardie, Christopher [University of Oxford, Materials Department (United Kingdom); Korsunsky, Alexander M. [University of Oxford, Dept. of Engineering Science (United Kingdom)

2013-12-31

Nanocrystalline metallic coatings of sub-micron thickness are widely used in modern microelectronic applications. In X-ray diffraction experiments to determine both the residual and applied stresses in nanocrystalline coatings, one difficult challenge that comes up invariably is the determination of the strain-free lattice spacing d{sub o}. The present study addresses this challenge by using the focused ion beam (FIB) to generate a built-in strain-free reference by patterning (milling) a 50 × 50 μm{sup 2} region of the coating to produce an array of small stress-relieved “islands” ∼ 0.8 × 0.8 μm{sup 2} each. Transmission X-ray diffraction setup was used for data collection at DIFFABS beamline (Synchrotron SOLEIL, France). A 150 nm-thick multi-layered W–Cu nano-composite thin film on polyimide (Kapton®) substrate was studied. The samples were loaded incrementally using a compact uniaxial loading device, and micro-beam diffraction data were collected on and away from the reference array. It was shown experimentally that the “island” array remained approximately strain free throughout the experiment, providing an on-board d{sub o} lattice spacing reference. The changing lattice spacing d in the coating was also monitored away from the array, to deduce the elastic strain evolution during deformation. The results and their implications are presented and discussed. - Highlights: • In situ deformation study of laminate polycrystalline W–Cu thin films • Focused ion beam (FIB) patterning of an array of “islands” on thin films surface • X-ray diffraction on island-patterned region • Constant strain on “islands” independently of the deformation of the substrate.

Precision analog signal processor for beam position measurements in electron storage rings

International Nuclear Information System (INIS)

Hinkson, J.A.; Unser, K.B.

1995-05-01

Beam position monitors (BPM) in electron and positron storage rings have evolved from simple systems composed of beam pickups, coaxial cables, multiplexing relays, and a single receiver (usually a analyzer) into very complex and costly systems of multiple receivers and processors. The older may have taken minutes to measure the circulating beam closed orbit. Today instrumentation designers are required to provide high-speed measurements of the beam orbit, often at the ring revolution frequency. In addition the instruments must have very high accuracy and resolution. A BPM has been developed for the Advanced Light Source (ALS) in Berkeley which features high resolution and relatively low cost. The instrument has a single purpose; to measure position of a stable stored beam. Because the pickup signals are multiplexed into a single receiver, and due to its narrow bandwidth, the receiver is not intended for single-turn studies. The receiver delivers normalized measurements of X and Y position entirely by analog means at nominally 1 V/mm. No computers are involved. No software is required. Bergoz, a French company specializing in precision beam instrumentation, integrated the ALS design m their new BPM analog signal processor module. Performance comparisons were made on the ALS. In this paper we report on the architecture and performance of the ALS prototype BPM

Geometrical E-beam proximity correction for raster scan systems

Science.gov (United States)

Belic, Nikola; Eisenmann, Hans; Hartmann, Hans; Waas, Thomas

1999-04-01

High pattern fidelity is a basic requirement for the generation of masks containing sub micro structures and for direct writing. Increasing needs mainly emerging from OPC at mask level and x-ray lithography require a correction of the e-beam proximity effect. The most part of e-beam writers are raster scan system. This paper describes a new method for geometrical pattern correction in order to provide a correction solution for e-beam system that are not able to apply variable doses.

Emittance measuring unit for 100% duty factor linac injector beams

Energy Technology Data Exchange (ETDEWEB)

Shubaly, M R; Pachner, J Jr; Ormrod, J H; Ungrin, J; Schriber, S O [ed.

1976-11-01

A description is given of a system to measure the emittance of a 750 keV 100 mA dc proton beam suitable for injection into a 100% duty factor linear accelerator. A relatively slowly pulsed 45/sup 0/ magnet switches the beam to a beam dump inside the emittance measuring unit for approx. 10 s. A fast pulsed 5/sup 0/ magnet then deflects the beam to a multiple aperture ''pepper-pot'' plate for 300 ..mu..s. Beamlets passing through the plate travel 520 mm and produce a pattern on a scintillator screen. A photograph of the pattern is analyzed to determine beam emittance. Preliminary results on low current beams show a gross increase in the emittance in the horizontal plane.

Nonlinear diffraction from a virtual beam

DEFF Research Database (Denmark)

Saltiel, Solomon M.; Neshev, Dragomir N.; Krolikowski, Wieslaw

2010-01-01

We observe experimentally a novel type of nonlinear diffraction in the process of two-wave mixing on a nonlinear quadratic grating.We demonstrate that when the nonlinear grating is illuminated simultaneously by two noncollinear beams, a second-harmonic diffraction pattern is generated by a virtual...... beam propagating along the bisector of the two pump beams. The observed iffraction phenomena is a purely nonlinear effect that has no analogue in linear diffraction...

Single beam write and/or replay of spatial heterodyne holograms

Science.gov (United States)

Thomas, Clarence E.; Hanson, Gregory R.

2007-11-20

A method of writing a spatially heterodyne hologram having spatially heterodyne fringes includes: passing a single write beam through a spatial light modulator that digitally modulates said single write beam; and focusing the single write beam at a focal plane of a lens to impose a holographic diffraction grating pattern on the photorefractive crystal, the holographic diffraction grating pattern including the spatially heterodyne hologram having spatially heterodyne fringes, wherein only said single write beam is incident on said photorefractive crystal without a reference beam. A method of replaying a spatially heterodyne hologram having spatially heterodyne fringes at a replay angle includes: illuminating a photorefractive crystal having a holographic diffraction grating with a beam from a laser at an illumination angle, the holographic diffraction grating pattern including the spatially heterodyne hologram having spatially heterodyne fringes, wherein a difference between said illumination angle and said replay angle defines a diffraction angle .alpha. that is a function of a plane wave mathematically added to original object wave phase and amplitude data of said spatially heterodyne hologram having spatially heterodyne fringes.

Beam lifetime measurement and analysis in Indus-2 electron ...

Indian Academy of Sciences (India)

In this paper, the beam lifetime measurement and its theoretical analysis are presented using measured vacuum pressure and applied radio frequency (RF) cavity voltage in Indus-2 electron storage ring at 2 GeV beam energy. Experimental studies of the effect of RF cavity voltage and bunched beam filling pattern on beam ...

THE HYDROGEN EPOCH OF REIONIZATION ARRAY DISH. I. BEAM PATTERN MEASUREMENTS AND SCIENCE IMPLICATIONS

International Nuclear Information System (INIS)

Neben, Abraham R.; Hewitt, Jacqueline N.; Ewall-Wice, Aaron; Bradley, Richard F.; DeBoer, David R.; Parsons, Aaron R.; Ali, Zaki S.; Cheng, Carina; Patra, Nipanjana; Dillon, Joshua S.; Aguirre, James E.; Kohn, Saul A.; Thyagarajan, Nithyanandan; Bowman, Judd; Jacobs, Daniel C.; Dickenson, Roger; Doolittle, Phillip; Egan, Dennis; Hedrick, Mike; Klima, Patricia J.

2016-01-01

The Hydrogen Epoch of Reionization Array (HERA) is a radio interferometer aiming to detect the power spectrum of 21 cm fluctuations from neutral hydrogen from the epoch of reionization (EOR). Drawing on lessons from the Murchison Widefield Array and the Precision Array for Probing the EOR, HERA is a hexagonal array of large (14 m diameter) dishes with suspended dipole feeds. The dish not only determines overall sensitivity, but also affects the observed frequency structure of foregrounds in the interferometer. This is the first of a series of four papers characterizing the frequency and angular response of the dish with simulations and measurements. In this paper, we focus on the angular response (i.e., power pattern), which sets the relative weighting between sky regions of high and low delay and thus apparent source frequency structure. We measure the angular response at 137 MHz using the ORBCOMM beam mapping system of Neben et al. We measure a collecting area of 93 m 2 in the optimal dish/feed configuration, implying that HERA-320 should detect the EOR power spectrum at z ∼ 9 with a signal-to-noise ratio of 12.7 using a foreground avoidance approach with a single season of observations and 74.3 using a foreground subtraction approach. Finally, we study the impact of these beam measurements on the distribution of foregrounds in Fourier space.

THE HYDROGEN EPOCH OF REIONIZATION ARRAY DISH. I. BEAM PATTERN MEASUREMENTS AND SCIENCE IMPLICATIONS

Energy Technology Data Exchange (ETDEWEB)

Neben, Abraham R.; Hewitt, Jacqueline N.; Ewall-Wice, Aaron [MIT Kavli Institute, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Bradley, Richard F. [Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, VA 22904 (United States); DeBoer, David R.; Parsons, Aaron R.; Ali, Zaki S.; Cheng, Carina; Patra, Nipanjana; Dillon, Joshua S. [Department of Astronomy, University of California, Berkeley, CA (United States); Aguirre, James E.; Kohn, Saul A. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA (United States); Thyagarajan, Nithyanandan; Bowman, Judd; Jacobs, Daniel C. [Arizona State University, School of Earth and Space Exploration, Tempe, AZ 85287 (United States); Dickenson, Roger; Doolittle, Phillip; Egan, Dennis; Hedrick, Mike; Klima, Patricia J. [National Radio Astronomy Observatory, Charlottesville, VA (United States); and others

2016-08-01

The Hydrogen Epoch of Reionization Array (HERA) is a radio interferometer aiming to detect the power spectrum of 21 cm fluctuations from neutral hydrogen from the epoch of reionization (EOR). Drawing on lessons from the Murchison Widefield Array and the Precision Array for Probing the EOR, HERA is a hexagonal array of large (14 m diameter) dishes with suspended dipole feeds. The dish not only determines overall sensitivity, but also affects the observed frequency structure of foregrounds in the interferometer. This is the first of a series of four papers characterizing the frequency and angular response of the dish with simulations and measurements. In this paper, we focus on the angular response (i.e., power pattern), which sets the relative weighting between sky regions of high and low delay and thus apparent source frequency structure. We measure the angular response at 137 MHz using the ORBCOMM beam mapping system of Neben et al. We measure a collecting area of 93 m{sup 2} in the optimal dish/feed configuration, implying that HERA-320 should detect the EOR power spectrum at z ∼ 9 with a signal-to-noise ratio of 12.7 using a foreground avoidance approach with a single season of observations and 74.3 using a foreground subtraction approach. Finally, we study the impact of these beam measurements on the distribution of foregrounds in Fourier space.

Investigation of fabrication process for sub 20-nm dense pattern of non-chemically amplified electron beam resist based on acrylic polymers

Science.gov (United States)

Ochiai, Shunsuke; Takayama, Tomohiro; Kishimura, Yukiko; Asada, Hironori; Sonoda, Manae; Iwakuma, Minako; Hoshino, Ryoichi

2016-10-01

In this study, we examine exposure characteristics of a positive tone electron beam resist consisting of methyl α- chloroacrylate and α-methylstyrene by changing the development process conditions. 25/25 nm and 30/30 nm line-andspace (L/S) patterns (design value) are developed in amyl and heptyl acetates. The resist patterns developed at 0ºC for 120 s show the better shapes having the vertical sidewalls than those developed at 22 °C for 60 s. The dose margins of pattern formation for 0°C development become wider, although the sensitivities are lower. The effect of post exposure baking (PEB) on exposure characteristics is also investigated. Adding PEB process performed at 120°C for 2 min, the dose margin also becomes wider although the sensitivity is lower. 20/20 nm L/S patterns are fabricated by using PEB and/or 0°C development. Though the required exposure dose is larger, the resist pattern is improved by PEB and/or 0°C development. The formation of 35 nm pitch pattern is also presented.

Fermilab Recycler Ring BPM Upgrade Based on Digital Receiver Technology

Science.gov (United States)

Webber, R.; Crisp, J.; Prieto, P.; Voy, D.; Briegel, C.; McClure, C.; West, R.; Pordes, S.; Mengel, M.

2004-11-01

Electronics for the 237 BPMs in the Fermilab Recycler Ring have been upgraded from a log-amplifier based system to a commercially produced digitizer-digital down converter based system. The hardware consists of a pre-amplifier connected to a split-plate BPM, an analog differential receiver-filter module and an 8-channel 80-MHz digital down converter VME board. The system produces position and intensity with a dynamic range of 30 dB and a resolution of ±10 microns. The position measurements are made on 2.5-MHz bunched beam and barrier buckets of the un-bunched beam. The digital receiver system operates in one of six different signal processing modes that include 2.5-MHz average, 2.5-MHz bunch-by-bunch, 2.5-MHz narrow band, unbunched average, un-bunched head/tail and 89-kHz narrow band. Receiver data is acquired on any of up to sixteen clock events related to Recycler beam transfers and other machine activities. Data from the digital receiver board are transferred to the front-end CPU for position and intensity computation on an on-demand basis through the VME bus. Data buffers are maintained for each of the acquisition events and support flash, closed orbit and turn-by-turn measurements. A calibration system provides evaluation of the BPM signal path and application programs.

Precision analog signal processor for beam position measurements in electron storage rings

International Nuclear Information System (INIS)

Hinkson, J.A.; Unser, K.B.

1995-01-01

Beam position monitors (BPM) in electron and positron storage rings have evolved from simple systems composed of beam pickups, coaxial cables, multiplexing relays, and a single receiver (usually a analyzer) into very complex and costly systems of multiple receivers and processors. The older may have taken minutes to measure the circulating beam closed orbit. Today instrumentation designers are required to provide high-speed measurements of the beam orbit, often at the ring revolution frequency. In addition the instruments must have very high accuracy and resolution. A BPM has been developed for the Advanced Light Source (ALS) in Berkeley which features high resolution and relatively low cost. The instrument has a single purpose; to measure position of a stable stored beam. Because the pickup signals are multiplexed into a single receiver, and due to its narrow bandwidth, the receiver is not intended for single-turn studies. The receiver delivers normalized measurements of X and Y posit ion entirely by analog means at nominally 1 V/mm. No computers are involved. No software is required. Bergoz, a French company specializing in precision beam instrumentation, integrated the ALS design m their new BPM analog signal processor module. Performance comparisons were made on the ALS. In this paper we report on the architecture and performance of the ALS prototype BPM

Evaluation of postradiotherapy PSA patterns and correlation with 10-year disease free survival outcomes for prostate cancer

International Nuclear Information System (INIS)

Zelefsky, Michael J.; Ben-Porat, Leah; Chan, Heather M.; Fearn, Paul A.; Venkatraman, Ennapadam S.

2006-01-01

Purpose: To describe the prostate-specific antigen (PSA) pattern profiles observed after external beam radiotherapy with and without short-term neoadjuvant androgen deprivation therapy (ST-ADT) and to report the association of established posttreatment PSA patterns with long-term disease-free survival outcomes. Methods and Materials: A total of 1,665 patients were treated with conformal external beam radiotherapy for clinically localized prostate cancer. Of 570 patients who had the requisite >10 consecutive PSA measurements for statistical analysis, 194 patients received a median of 3 months of ADT before radiotherapy and 376 were treated with radiotherapy alone. The median follow up was 103 months. Results: In the group treated with ST-ADT, three distinct postradiotherapy PSA patterns were identified: a stable trend (44%), an increasing trend followed by stabilization of the PSA (25%), and an increasing trend (31%). Among the subgroup that demonstrated a rising and subsequent stabilizing patterns, PSA levels had gradually risen to a median value of 0.9 ng/mL after therapy, stabilized, and remained durably suppressed. The only identified trends among patients treated with external beam radiotherapy without ST-ADT were declining PSA levels followed by stable PSA trends or declining patterns followed by rising levels. Patients whose PSA levels stabilized after an initial rise or those with slowly rising PSA profiles had a lower incidence of distant metastasis compared to those with accelerated rises after therapy. Conclusions: For those treated with external beam radiotherapy in conjunction with ST-ADT, a significant percentage who develop a rising PSA after treatment are expected to manifest subsequent stabilization at plateaued levels of approximately 1.0 ng/mL, which can remain durably suppressed. The likelihood of distant metastasis in these patients is low despite the PSA stabilization at levels 1.0 ng/mL or higher and comparable to outcomes observed for those

Infrared beam-steering using acoustically modulated surface plasmons over a graphene monolayer

KAUST Repository

Chen, Paiyen

2014-09-01

We model and design a graphene-based infrared beamformer based on the concept of leaky-wave (fast traveling wave) antennas. The excitation of infrared surface plasmon polaritons (SPPs) over a \\'one-atom-thick\\' graphene monolayer is typically associated with intrinsically \\'slow light\\'. By modulating the graphene with elastic vibrations based on flexural waves, a dynamic diffraction grating can be formed on the graphene surface, converting propagating SPPs into fast surface waves, able to radiate directive infrared beams into the background medium. This scheme allows fast on-off switching of infrared emission and dynamic tuning of its radiation pattern, beam angle and frequency of operation, by simply varying the acoustic frequency that controls the effective grating period. We envision that this graphene beamformer may be integrated into reconfigurable transmitter/receiver modules, switches and detectors for THz and infrared wireless communication, sensing, imaging and actuation systems.

Hermite-cosine-Gaussian laser beam and its propagation characteristics in turbulent atmosphere.

Science.gov (United States)

Eyyuboğlu, Halil Tanyer

2005-08-01

Hermite-cosine-Gaussian (HcosG) laser beams are studied. The source plane intensity of the HcosG beam is introduced and its dependence on the source parameters is examined. By application of the Fresnel diffraction integral, the average receiver intensity of HcosG beam is formulated for the case of propagation in turbulent atmosphere. The average receiver intensity is seen to reduce appropriately to various special cases. When traveling in turbulence, the HcosG beam initially experiences the merging of neighboring beam lobes, and then a TEM-type cosh-Gaussian beam is formed, temporarily leading to a plain cosh-Gaussian beam. Eventually a pure Gaussian beam results. The numerical evaluation of the normalized beam size along the propagation axis at selected mode indices indicates that relative spreading of higher-order HcosG beam modes is less than that of the lower-order counterparts. Consequently, it is possible at some propagation distances to capture more power by using higher-mode-indexed HcosG beams.

Quasi-Airy beams along tunable propagation trajectories and directions.

Science.gov (United States)

Qian, Yixian; Zhang, Site

2016-05-02

We present a theoretical and experimental exhibit that accelerates quasi-Airy beams propagating along arbitrarily appointed parabolic trajectories and directions in free space. We also demonstrate that such quasi-Airy beams can be generated by a tunable phase pattern, where two disturbance factors are introduced. The topological structures of quasi-Airy beams are readily manipulated with tunable phase patterns. Quasi-Airy beams still possess the characteristics of non-diffraction, self-healing to some extent, although they are not the solutions for paraxial wave equation. The experiments show the results are consistent with theoretical predictions. It is believed that the property of propagation along arbitrarily desired parabolic trajectories will provide a broad application in trapping atom and living cell manipulation.

High-k Scattering Receiver Mixer Performance for NSTX-U

Science.gov (United States)

Barchfeld, Robert; Riemenschneider, Paul; Domier, Calvin; Luhmann, Neville; Ren, Yang; Kaita, Robert

2016-10-01

The High-k Scattering system detects primarily electron-scale turbulence k θ spectra for studying electron thermal transport in NSTX-U. A 100 mW, 693 GHz probe beam passes through plasma, and scattered power is detected by a 4-pixel quasi optical, mixer array. Remotely controlled receiving optics allows the scattering volume to be located from core to edge with a k θ span of 7 to 40 cm-1. The receiver array features 4 RF diagonal input horns, where the electric field polarization is aligned along the diagonal of a square cross section horn, at 30 mm channel spacing. The local oscillator is provided by a 14.4 GHz source followed by a x48 multiplier chain, giving an intermediate frequency of 1 GHz. The receiver optics receive 4 discreet scattering angles simultaneously, and then focus the signals as 4 parallel signals to their respective horns. A combination of a steerable probe beam, and translating receiver, allows for upward or downward scattering which together can provide information about 2D turbulence wavenumber spectrum. IF signals are digitized and stored for later computer analysis. The performance of the receiver mixers is discussed, along with optical design features to enhance the tuning and performance of the mixers. Work supported in part by U.S. DOE Grant DE-FG02-99ER54518 and DE-AC02-09CH1146.

Highly ordered nanopatterns on Ge and Si surfaces by ion beam sputtering

International Nuclear Information System (INIS)

Ziberi, B; Cornejo, M; Frost, F; Rauschenbach, B

2009-01-01

The bombardment of surfaces with low-energy ion beams leads to material erosion and can be accompanied by changes in the topography. Under certain conditions this surface erosion can result in well-ordered nanostructures. Here an overview of the pattern formation on Si and Ge surfaces under low-energy ion beam erosion at room temperature will be given. In particular, the formation of ripple and dot patterns, and the influence of different process parameters on their formation, ordering, shape and type will be discussed. Furthermore, the internal ion beam parameters inherent to broad beam ion sources are considered as an additional degree of freedom for controlling the pattern formation process. In this context: (i) formation of ripples at near-normal ion incidence, (ii) formation of dots at oblique ion incidence without sample rotation, (iii) transition between patterns, (iv) formation of ripples with different orientations and (v) long range ordered dot patterns will be presented and discussed.

Effect of Gamma Radiation and Electron Beam on Microbiological Quality and Protein Patterns of 4 Selected Beans

International Nuclear Information System (INIS)

Chookaew, S.; Eamsir, J.; Pewlong, W.; Sajjabut, S.

2014-01-01

The aim of the present study was to evaluate the effect of gamma ray and electron beam on microbiological quality and protein pattern of four selected beans: mung beans, soy beans, peanuts and black beans. All beans samples were exposed to irradiation at doses of 0, 0.5, 1, and 2 kGy before evaluated for their microbiological quality using AOAC method and protein analysis by gel electrophoresis. Results showed that the amount of bacteria, yeast and mold of irradiated mung beans and peanuts were reduced, whereas these microbiological quality values remained relatively the same for irradiated soy beans and black beans compared to non-irradiated samples. In terms of protein analysis, the protein patterns of the irradiated beans were of the same quality as the non-irradiated samples. To further tested the effect of irradiation on the bean's protein at higher doses, all four selected beans were exposed to gamma ray at 10, 50, 100, 150 and 200 kGy. We found that the protein patterns of mung beans, peanuts and black beans were altered at doses above 50 kGy.

Ion beam profiling from the interaction with a freestanding 2D layer

Directory of Open Access Journals (Sweden)

Ivan Shorubalko

2017-03-01

Full Text Available Recent years have seen a great potential of the focused ion beam (FIB technology for the nanometer-scale patterning of a freestanding two-dimensional (2D layer. Experimentally determined sputtering yields of the perforation process can be quantitatively explained using the binary collision theory. The main peculiarity of the interaction between the ion beams and the suspended 2D material lies in the absence of collision cascades, featured by no interaction volume. Thus, the patterning resolution is directly set by the beam diameters. Here, we demonstrate pattern resolution beyond the beam size and precise profiling of the focused ion beams. We find out that FIB exposure time of individual pixels can influence the resultant pore diameter. In return, the pore dimension as a function of the exposure dose brings out the ion beam profiles. Using this method of determining an ion-beam point spread function, we verify a Gaussian profile of focused gallium ion beams. Graphene sputtering yield is extracted from the normalization of the measured Gaussian profiles, given a total beam current. Interestingly, profiling of unbeknown helium ion beams in this way results in asymmetry of the profile. Even triangular beam shapes are observed at certain helium FIB conditions, possibly attributable to the trimer nature of the beam source. Our method of profiling ion beams with 2D-layer perforation provides more information on ion beam profiles than the conventional sharp-edge scan method does.

Transverse Periodic Beam Loading Effects in a Storage Ring

International Nuclear Information System (INIS)

Thompson, J.R.; Byrd, J.M.

2009-01-01

Uneven beam fill patterns in storage rings, such as gaps in the fill patterns, leads to periodic, or transient loading of the modes of the RF cavities. We show that an analogous effect can occur in the loading of a dipole cavity mode when the beam passes off the electrical center of the cavity mode. Although this effect is small, it results in a variation of the transverse offset of the beam along the bunch train. For ultralow emittance beams, such as optimized third generation light sources and damping rings, this effect results in a larger projected emittance of the beam compared with the single bunch emittance. The effect is particularly strong for the case when a strong dipole mode has been purposely added to the ring, such as a deflecting, or 'crab' cavity. We derive an approximate analytic solution for the variation of the beam-induced deflecting voltage along the bunch train.

Using a short-pulse diffraction-limited laser beam to probe filamentation of a random phase plate smoothed beam

International Nuclear Information System (INIS)

Kline, J. L.; Montgomery, D. S.; Flippo, K. A.; Johnson, R. P.; Rose, H. A.; Shimada, T.; Williams, E. A.

2008-01-01

A short pulse (few picoseconds) laser probe provides high temporal resolution measurements to elucidate details of fast dynamic phenomena not observable with typical longer laser pulse probes and gated diagnostics. Such a short pulse laser probe (SPLP) has been used to measure filamentation of a random phase plate (RPP) smoothed laser beam in a gas-jet plasma. The plasma index of refraction due to driven density and temperature fluctuations by the RPP beam perturbs the phase front of a SPLP propagating at a 90 deg. angle with respect to the RPP interaction beam. The density and temperature fluctuations are quasistatic on the time scale of the SPLP (∼2 ps). The transmitted near-field intensity distribution from the SPLP provides a measure of the phase front perturbation. At low plasma densities, the transmitted intensity pattern is asymmetric with striations across the entire probe beam in the direction of the RPP smoothed beam. As the plasma density increases, the striations break up into smaller sizes along the direction of the RPP beam propagation. The breakup of the intensity pattern is consistent with self-focusing of the RPP smoothed interaction beam. Simulations of the experiment using the wave propagation code, PF3D, are in qualitative agreement demonstrating that the asymmetric striations can be attributed to the RPP driven density fluctuations. Quantification of the beam breakup measured by the transmitted SPLP could lead to a new method for measuring self-focusing of lasers in underdense plasmas.

Using a short-pulse diffraction-limited laser beam to probe filamentation of a random phase plate smoothed beam.

Science.gov (United States)

Kline, J L; Montgomery, D S; Flippo, K A; Johnson, R P; Rose, H A; Shimada, T; Williams, E A

2008-10-01

A short pulse (few picoseconds) laser probe provides high temporal resolution measurements to elucidate details of fast dynamic phenomena not observable with typical longer laser pulse probes and gated diagnostics. Such a short pulse laser probe (SPLP) has been used to measure filamentation of a random phase plate (RPP) smoothed laser beam in a gas-jet plasma. The plasma index of refraction due to driven density and temperature fluctuations by the RPP beam perturbs the phase front of a SPLP propagating at a 90 degree angle with respect to the RPP interaction beam. The density and temperature fluctuations are quasistatic on the time scale of the SPLP (approximately 2 ps). The transmitted near-field intensity distribution from the SPLP provides a measure of the phase front perturbation. At low plasma densities, the transmitted intensity pattern is asymmetric with striations across the entire probe beam in the direction of the RPP smoothed beam. As the plasma density increases, the striations break up into smaller sizes along the direction of the RPP beam propagation. The breakup of the intensity pattern is consistent with self-focusing of the RPP smoothed interaction beam. Simulations of the experiment using the wave propagation code, PF3D, are in qualitative agreement demonstrating that the asymmetric striations can be attributed to the RPP driven density fluctuations. Quantification of the beam breakup measured by the transmitted SPLP could lead to a new method for measuring self-focusing of lasers in underdense plasmas.

Radical external beam radiotherapy for prostate cancer in Japan. Differences in the patterns of care between Japan and the United States

International Nuclear Information System (INIS)

Ogawa, Kazuhiko; Nakamura, Katsumasa; Sasaki, Tomonari; Onishi, Hiroshi; Araya, Masayuki; Koizumi, Masahiko; Okamoto, Atsushi; Tejima, Teruki; Mitsumori, Michihide

2007-01-01

This study focused on the differences in the patterns of care for prostate cancer patients treated with radical external beam radiotherapy between Japan and the United States. Results from the 1999-2001 Japanese Patterns of Care Study (PCS) survey were compared with those of the 1999 PCS in the United States. In addition, the changing trends in the patterns of care between Japan and the United States were also analyzed. Patients in Japan were found to have more advanced primary disease than those in the United States, but the proportions of advanced disease have gradually decreased in Japan. The distributions of CT-based treatment planning, conformal therapy and higher doses were higher in the United States, and a drastic change in these parameters occurred in the United States, while only moderate changes occurred in Japan. These results indicate that patterns of care for prostate cancer in Japan are considerably different from those in the United States, and the changing trends in the patterns of care are also different between the two countries. (author)

Observation of an optical vortex beam from a helical undulator in the XUV region.

Science.gov (United States)

Kaneyasu, Tatsuo; Hikosaka, Yasumasa; Fujimoto, Masaki; Iwayama, Hiroshi; Hosaka, Masahito; Shigemasa, Eiji; Katoh, Masahiro

2017-09-01

The observation of an optical vortex beam at 60 nm wavelength, produced as the second-harmonic radiation from a helical undulator, is reported. The helical wavefront of the optical vortex beam was verified by measuring the interference pattern between the vortex beam from a helical undulator and a normal beam from another undulator. Although the interference patterns were slightly blurred owing to the relatively large electron beam emittance, it was possible to observe the interference features thanks to the helical wavefront of the vortex beam. The experimental results were well reproduced by simulation.

Vertical and horizontal assemblage patterns of bacterial communities in a eutrophic river receiving domestic wastewater in southeast China.

Science.gov (United States)

Gao, Yan; Wang, Chengcheng; Zhang, Weiguo; Di, Panpan; Yi, Neng; Chen, Chengrong

2017-11-01

Bacterial communities in rivers receiving untreated domestic wastewater may show specific spatial assemblage patterns due to a wide range of physicochemical conditions created by periodic algal bloom. However, there are significant gaps in understanding environmental forces that drive changes in microbial assemblages in polluted rivers. In this study, we applied high-throughput sequencing of 16S rRNA gene amplicons to perform comprehensive spatio-temporal profiling of bacterial community structure in a local river segment receiving domestic wastewater discharge in southeast China. Multivariate statistics were then used to analyse links between bacterial community structure and environmental factors. Non-metric multidimensional scaling (NMDS) plots showed that the bacterial community structure was different between upstream and downstream sections of the river. While the upstream water contained a high proportion of bacteria degrading xenobiotic aromatic compounds, the downstream water experiencing stronger algal bloom had a more diverse bacterial community which included the genus Aeromonas comprising 14 species, most of which are human pathogens. Least discriminant analysis (LDA) effect size revealed that the surface water was mainly inhabited by aerobic microorganisms capable of degrading aromatic compounds, and also contained bacterial genera including pathogenic species. In contrast, in the bottom water we found, along with aromatic compound-degrading species, anaerobic denitrifiers and Fe 3+ -reducing and fermentative bacteria. Variance partitioning canonical correspondence analysis (VPA) showed that nutrient ratios had a stronger contribution to bacterial dissimilarities than other major physicochemical factors (temperature, pH, dissolved oxygen, total organic carbon, and chlorophyll a). These results show that microbial communities in rivers continuously receiving domestic wastewater have specific longitudinal and vertical assemblage patterns and may contain

SU-F-T-338: Flattening Filter Free Photon Beams Can Achieve the Same Plan Quality as Conventional Flattened Beams for Prostate Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Kolar, M; Szwedowski, R; Greskovich, J; Xia, P [Cleveland Clinic, Cleveland, OH (United States)

2016-06-15

Purpose: Some modern linear accelerators are equipped with one low energy flat beam and two flattening filter free (FFF) beams at high and low energies. The purpose of this study is to investigate whether the high energy FFF beam can produce the same plan quality as the conventional low energy flat beam, using a volumetric modulated arc (VMAT) technique for prostate patients. Methods: Ten prostate cancer patients were selected with a prescription of 78Gy. For each patient, three plans were created: (a) double arc flat 6MV plan used clinically; (b) double arc 10MV FFF plan; (c) single arc 10MV FFF plan. Each plan was prescribed so that at least 95% of the PTV received the prescription dose. The following dosimetric endpoints were evaluated: volume receiving 78Gy (V78) of the CTV and PTV, PTV conformality index (CI, ratio of prescription isodose volume to the PTV volume), bladder volume receiving 70Gy (V70) and 60Gy (V60), rectum volume receiving 70Gy (V70) and 50Gy (V50), dose to 10cc of the rectum, and volume of both femoral heads receiving 50Gy (V50). Total monitor units for each plan were recorded. Results: No significant difference was found for all dosimetric endpoints between all plans (p>0.05). Compared to the 6MV plans, monitor units were higher with the double arc 10MV FFF plans and lower with the single arc 10MV FFF plans, 29% and 4% respectively. Conclusion: Both single arc and double arc 10MV FFF VMAT can achieve equivalent plan quality as 6MV flat beam double arc treatment plans. With the gantry speed restriction, a high dose rate of 2400MU/min may allow the optimizer to use more MUs than actually needed. Single arc 10MV FFF VMAT plans are a reasonable alternative to double arc 6MV flat beam VMAT plans.

SU-F-T-338: Flattening Filter Free Photon Beams Can Achieve the Same Plan Quality as Conventional Flattened Beams for Prostate Radiotherapy

International Nuclear Information System (INIS)

Kolar, M; Szwedowski, R; Greskovich, J; Xia, P

2016-01-01

Purpose: Some modern linear accelerators are equipped with one low energy flat beam and two flattening filter free (FFF) beams at high and low energies. The purpose of this study is to investigate whether the high energy FFF beam can produce the same plan quality as the conventional low energy flat beam, using a volumetric modulated arc (VMAT) technique for prostate patients. Methods: Ten prostate cancer patients were selected with a prescription of 78Gy. For each patient, three plans were created: (a) double arc flat 6MV plan used clinically; (b) double arc 10MV FFF plan; (c) single arc 10MV FFF plan. Each plan was prescribed so that at least 95% of the PTV received the prescription dose. The following dosimetric endpoints were evaluated: volume receiving 78Gy (V78) of the CTV and PTV, PTV conformality index (CI, ratio of prescription isodose volume to the PTV volume), bladder volume receiving 70Gy (V70) and 60Gy (V60), rectum volume receiving 70Gy (V70) and 50Gy (V50), dose to 10cc of the rectum, and volume of both femoral heads receiving 50Gy (V50). Total monitor units for each plan were recorded. Results: No significant difference was found for all dosimetric endpoints between all plans (p>0.05). Compared to the 6MV plans, monitor units were higher with the double arc 10MV FFF plans and lower with the single arc 10MV FFF plans, 29% and 4% respectively. Conclusion: Both single arc and double arc 10MV FFF VMAT can achieve equivalent plan quality as 6MV flat beam double arc treatment plans. With the gantry speed restriction, a high dose rate of 2400MU/min may allow the optimizer to use more MUs than actually needed. Single arc 10MV FFF VMAT plans are a reasonable alternative to double arc 6MV flat beam VMAT plans.

Treatment planning for carcinoma of the cervix: a patterns of care study report

International Nuclear Information System (INIS)

Ling, C. Clifton; Smith, Alfred R.; Hanlon, Alexandra L.; Owen, Jean B.; Brickner, Theodore J.; Hanks, Gerald E.

1996-01-01

3% outlining the bladder, 5% the rectum, and less than 1% the small bowel. Only 11% of the centers used CT in treatment planning, and none reported the use of magnetic resonance imaging (MRI). For patients receiving implants, about 40% had midline blocking during external beam treatment, of which one out of three were shielded by standard blocks and two out of three with customized ones. About 11% of the patients receiving implants were treated with remote afterloading devices, 5% received interstitial implants, and none were treated in combination with hyperthermia. Conclusion: The treatment planning aspects of radiotherapy of carcinoma of the cervix have been established by this Patterns of Care Study Survey. There is a high level of uniformity in the approach. Some variations exist among centers in the different strata

Wakefield and the diffraction model due to a flat beam moving past a conducting wedge

International Nuclear Information System (INIS)

Chao, A.W.; Henke, H.

1995-07-01

A collimator is often used to clean a beam of its excessive tail particles. If the beam intensity is high enough or if the beam is brought too close to the collimator, however, the wakefields generated by the beam-collimator interaction can cause additional beam tails to grow, thus defeating, or even worsening, the beam-tail cleaning process. The wakefield generated by a sheet beam moving past a conducting wedge has been obtained in closed form by Henke using the method of conformal mapping. This result is applied in the present work to obtain the wake force and the transverse kick received by a test charge moving with the beam. For the beam to be approximated as sheet beams, it is assumed to be flat and the collimator is assumed to have an infinite extent in the flat dimention. We derive an exact expression for the transverse wake force delivered to particles in the beam bunch. Implication of emittance growth as a beam passes closely by a collimator is discussed. We consider two idealized wedge geometries: In Section 2, when the wedge has the geometry as a disrupted beam pipe, and in Section 3, when it is like a semi-infinite screen. Unfortunately, we do not have solutions for more realistic collimator geometries such as when it is tapered to minimize the wakefield effects. However, our results should still serve as pessimistic limiting cases. An interesting opportunity is offered by our exact calculation of the wakefields: it can be used to confront the diffraction model used to estimate the high-frequency impedance of a cavity structure. It is shown that the field pattern, as well as the impedance, agrees with those obtained by the diffraction model in appropriate limits

Simulations and measurements of beam loss patterns at the CERN Large Hadron Collider

CERN Document Server

Bruce, R.; Boccone, V.; Bracco, C.; Brugger, M.; Cauchi, M.; Cerutti, F.; Deboy, D.; Ferrari, A.; Lari, L.; Marsili, A.; Mereghetti, A.; Mirarchi, D.; Quaranta, E.; Redaelli, S.; Robert-Demolaize, G.; Rossi, A.; Salvachua, B.; Skordis, E.; Tambasco, C.; Valentino, G.; Weiler, T.; Vlachoudis, V.; Wollmann, D.

2014-08-21

The CERN Large Hadron Collider (LHC) is designed to collide proton beams of unprecedented energy, in order to extend the frontiers of high-energy particle physics. During the first very successful running period in 2010--2013, the LHC was routinely storing protons at 3.5--4 TeV with a total beam energy of up to 146 MJ, and even higher stored energies are foreseen in the future. This puts extraordinary demands on the control of beam losses. An un-controlled loss of even a tiny fraction of the beam could cause a superconducting magnet to undergo a transition into a normal-conducting state, or in the worst case cause material damage. Hence a multi-stage collimation system has been installed in order to safely intercept high-amplitude beam protons before they are lost elsewhere. To guarantee adequate protection from the collimators, a detailed theoretical understanding is needed. This article presents results of numerical simulations of the distribution of beam losses around the LHC that have leaked out of the co...

First-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Beam Profiles and Window Functions

Science.gov (United States)

Page, L.; Barnes, C.; Hinshaw, G.; Spergel, D. N.; Weiland, J. L.; Wollack, E.; Bennett, C. L.; Halpern, M.; Jarosik, N.; Kogut, A.; Limon, M.; Meyer, S. S.; Tucker, G. S.; Wright, E. L.

2003-09-01

Knowledge of the beam profiles is of critical importance for interpreting data from cosmic microwave background experiments. In this paper, we present the characterization of the in-flight optical response of the WMAP satellite. The main-beam intensities have been mapped to the satellite in the same observing mode as for CMB observations. The beam patterns closely follow the prelaunch expectations. The full width at half-maximum is a function of frequency and ranges from 0.82d at 23 GHz to 0.21d at 94 GHz; however, the beams are not Gaussian. We present (a) the beam patterns for all 10 differential radiometers, showing that the patterns are substantially independent of polarization in all but the 23 GHz channel; (b) the effective symmetrized beam patterns that result from WMAP's compound spin observing pattern; (c) the effective window functions for all radiometers and the formalism for propagating the window function uncertainty; and (d) the conversion factor from point-source flux to antenna temperature. A summary of the systematic uncertainties, which currently dominate our knowledge of the beams, is also presented. The constancy of Jupiter's temperature within a frequency band is an essential check of the optical system. The tests enable us to report a calibration of Jupiter to 1%-3% accuracy relative to the CMB dipole. WMAP is the result of a partnership between Princeton University and the NASA Goddard Space Flight Center. Scientific guidance is provided by the WMAP Science Team.

Experimental studies with radioactive ion beams

International Nuclear Information System (INIS)

Sastry, D.L.; Sree Krishna Murty, G.; Chandrasekhar Rao, M.V.S.

1991-01-01

The sources of information presented are essentially taken from the papers reported at several international seminars and those appeared in the Journal of Nuclear Instruments and Methods in Physics Research. Production and usage of radioactive ion beams (RIB) in research have received the attention of scientists all over the world during the past six years. The first radioactive ion beams ( 19 Ne) were produced at Bevalac for the purpose of medical research using a primary beam of energy 800 MeV/a.m.u. (author). 19 refs., 2 figs., 3 tabs

Analysis of RHIC beam dump pre-fires

International Nuclear Information System (INIS)

Zhang, W.; Ahrens, L.; Fischer, W.; Hahn, H.; Mi, J.; Sandberg, J.; Tan, Y.

2011-01-01

It has been speculated that the beam may cause instability of the RHIC Beam Abort Kickers. In this study, we explore the available data of past beam operations, the device history of key modulator components, and the radiation patterns to examine the correlations. The RHIC beam abort kicker system was designed and built in the 90's. Over last decade, we have made many improvements to bring the RHIC beam abort kicker system to a stable operational state. However, the challenge continues. We present the analysis of the pre-fire, an unrequested discharge of kicker, issues which relates to the RHIC machine safety and operational stability.

Development of an MeV ion beam lithography system in Jyvaeskylae

Energy Technology Data Exchange (ETDEWEB)

Gorelick, Sergey [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FIN-40014 (Finland)]. E-mail: Sergey.Gorelick@phys.jyu.fi; Ylimaeki, Tommi [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FIN-40014 (Finland); Sajavaara, Timo [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FIN-40014 (Finland); Laitinen, Mikko [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FIN-40014 (Finland); Sagari, A.R.A. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FIN-40014 (Finland); Whitlow, Harry J. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FIN-40014 (Finland)

2007-07-15

A lithographic facility for writing patterns with ion beams from cyclotron beams is under development for the Jyvaeskylae cyclotron. Instead of focusing and deflecting the beam with electrostatic and magnetic fields a different approach is used. Here a small rectangular beam spot is defined by the shadow of a computer-controlled variable aperture in close proximity to the sample. This allows parallel exposure of rectangular pattern elements of 5-500 {mu}m side with protons up to 6 MeV and heavy ions ({sup 20}Ne, {sup 85}Kr) up to few 100 MeV. Here we present a short overview of the system under construction and development of the aperture design, which is a critical aspect for all ion beam lithography systems.

Low noise 874 GHz receivers for the International Submillimetre Airborne Radiometer (ISMAR)

Science.gov (United States)

Hammar, A.; Sobis, P.; Drakinskiy, V.; Emrich, A.; Wadefalk, N.; Schleeh, J.; Stake, J.

2018-05-01

We report on the development of two 874 GHz receiver channels with orthogonal polarizations for the International Submillimetre Airborne Radiometer. A spline horn antenna and dielectric lens, a Schottky diode mixer circuit, and an intermediate frequency (IF) low noise amplifier circuit were integrated in the same metallic split block housing. This resulted in a receiver mean double sideband (DSB) noise temperature of 3300 K (minimum 2770 K, maximum 3400 K), achieved at an operation temperature of 40 °C and across a 10 GHz wide IF band. A minimum DSB noise temperature of 2260 K at 20 °C was measured without the lens. Three different dielectric lens materials were tested and compared with respect to the radiation pattern and noise temperature. All three lenses were compliant in terms of radiation pattern, but one of the materials led to a reduction in noise temperature of approximately 200 K compared to the others. The loss in this lens was estimated to be 0.42 dB. The local oscillator chains have a power consumption of 24 W and consist of custom-designed Schottky diode quadruplers (5% power efficiency in operation, 8%-9% peak), commercial heterostructure barrier varactor (HBV) triplers, and power amplifiers that are pumped by using a common dielectric resonator oscillator at 36.43 GHz. Measurements of the radiation pattern showed a symmetric main beam lobe with full width half maximum <5° and side lobe levels below -20 dB. Return loss of a prototype of the spline horn and lens was measured using a network analyzer and frequency extenders to 750-1100 GHz. Time-domain analysis of the reflection coefficients shows that the reflections are below -25 dB and are dominated by the external waveguide interface.

Nanoscale pattern formation at surfaces under ion-beam sputtering: A perspective from continuum models

International Nuclear Information System (INIS)

Cuerno, Rodolfo; Castro, Mario; Munoz-Garcia, Javier; Gago, Raul; Vazquez, Luis

2011-01-01

Although reports on surface nanostructuring of solid targets by low to medium energy ion irradiation date back to the 1960s, only with the advent of high resolution tools for surface/interface characterization has the high potential of this procedure been recognized as a method for efficient production of surface patterns. Such morphologies are made up of periodic arrangements of nanometric sized features, like ripples and dots, with interest for technological applications due to their electronic, magnetic, and optical properties. Thus, roughly for the last ten years large efforts have been directed towards harnessing this nanofabrication technique. However, and particularly in view of recent experimental developments, we can say that the basic mechanisms controlling these pattern formation processes remain poorly understood. The lack of nanostructuring at low angles of incidence on some pure monoelemental targets, the role of impurities in the surface dynamics and other recent observations are challenging the classic view on the phenomenon as the mere interplay between the curvature dependence of the sputtering yield and surface diffusion. We review the main attempts at a theoretical (continuum) description of these systems, with emphasis on recent developments. Strong hints already exist that the nature of the morphological instability has to be rethought as originating in the material flow that is induced by the ion beam.

Patterns of ventricular dysfunction in patients receiving cardiotoxic chemotherapy as assessed with gated blood pool imaging

International Nuclear Information System (INIS)

Spies, S.M.; Parikh, S.R.; Spies, W.G.; Zimmer, A.M.; Silverstein, E.A.

1989-01-01

Clinical concern over significant cardiotoxicity of commonly employed chemotherapeutic regimens is a common indication for gated blood pool imaging. The authors have undertaken a review of 102 patients referred for such evaluation during a 14-month period. Ventricular ejection fractions, cine displays, and phase analysis were performed on each patient study. Approximately one-third of the cases showed significant abnormalities in wall motion or global ejection fraction. Many abnormal cases had isolated left ventricular findings, while fewer had isolated right ventricular findings. Left ventricular wall motion abnormalities were often focal. The patterns of ventricular dysfunction in patients receiving cardiotoxic chemotherapy are diverse, and awareness of the various possibilities is important for accurate clinical assessment of these patients

The family receiving home care: functional health pattern assessment.

Science.gov (United States)

Hooper, J I

1996-01-01

The winds of change in health care make assessment of the family more important than ever as a tool for health care providers seeking to assist the family move themselves toward high-level wellness. Limited medical care and imposed self-responsibility for health promotion and illness prevention, which are natural consequences of these changes, move the locus of control for health management back to the family. The family's teachings, modeling, and interactions are greater influences than ever on the health of the patient. Gordon's functional health patterns provide a holistic model for assessment of the family because assessment data are classified under 11 headings: health perception and health management, nutritional-metabolic, elimination, activity and exercise, sleep and rest, cognition and perception, self-perception and self-concept, roles and relationships, sexuality and reproduction, coping and stress tolerance, and values and beliefs. Questions posed under each of the health patterns can be varied to reflect the uniqueness of the individual family as well as to inquire about family strengths and weaknesses in all patterns. Data using this model provide a comprehensive base for including the family in designing a plan of care.

Integrated Lens Antennas for Multi-Pixel Receivers

Science.gov (United States)

Lee, Choonsup; Chattopadhyay, Goutam

2011-01-01

Future astrophysics and planetary experiments are expected to require large focal plane arrays with thousands of detectors. Feedhorns have excellent performance, but their mass, size, fabrication challenges, and expense become prohibitive for very large focal plane arrays. Most planar antenna designs produce broad beam patterns, and therefore require additional elements for efficient coupling to the telescope optics, such as substrate lenses or micromachined horns. An antenna array with integrated silicon microlenses that can be fabricated photolithographically effectively addresses these issues. This approach eliminates manual assembly of arrays of lenses and reduces assembly errors and tolerances. Moreover, an antenna array without metallic horns will reduce mass of any planetary instrument significantly. The design has a monolithic array of lens-coupled, leaky-wave antennas operating in the millimeter- and submillimeter-wave frequencies. Electromagnetic simulations show that the electromagnetic fields in such lens-coupled antennas are mostly confined in approximately 12 15 . This means that one needs to design a small-angle sector lens that is much easier to fabricate using standard lithographic techniques, instead of a full hyper-hemispherical lens. Moreover, this small-angle sector lens can be easily integrated with the antennas in an array for multi-pixel imager and receiver implementation. The leaky antenna is designed using double-slot irises and fed with TE10 waveguide mode. The lens implementation starts with a silicon substrate. Photoresist with appropriate thickness (optimized for the lens size) is spun on the substrate and then reflowed to get the desired lens structure. An antenna array integrated with individual lenses for higher directivity and excellent beam profile will go a long way in realizing multi-pixel arrays and imagers. This technology will enable a new generation of compact, low-mass, and highly efficient antenna arrays for use in multi

Experiment for dose measurement during beam killing at Indus-1 synchrotron radiation source

International Nuclear Information System (INIS)

Nayak, M.K.; Dev, Vipin; Haridas, G.; Thakkar, K.K.; Sarkar, P.K.; Sharma, D.N.

2006-01-01

Experimental measurement of radiation dose likely to be received by an occupational worker in the experimental hall of Indus-1 during accidental beam killing was carried out. Various accidental beam-killing scenarios were experimentally simulated for the measurement. The measurement was carried out using direct reading dosimeters. Result shows that in the event of accidental beam killing, dose likely to be received by an occupational worker outside the shield is negligible. (author)

Structured electron beams from nano-engineered cathodes

Energy Technology Data Exchange (ETDEWEB)

Lueangaramwong, A. [NICADD, DeKalb; Mihalcea, D. [NICADD, DeKalb; Andonian, G. [RadiaBeam Tech.; Piot, P. [Fermilab

2017-03-07

The ability to engineer cathodes at the nano-scale have open new possibilities such as enhancing quantum eciency via surface-plasmon excitation, forming ultra-low-emittance beams, or producing structured electron beams. In this paper we present numerical investigations of the beam dynamics associated to this class of cathode in the weak- and strong-field regimes.We finally discuss the possible applications of some of the achievable cathode patterns when coupled with other phase space manipulations.

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

Fabrication of Si surface pattern by Ar beam irradiation and annealing method

International Nuclear Information System (INIS)

Zhang, J.; Momota, S.; Maeda, K.; Terauchi, H.; Furuta, M.; Kawaharamura, T.; Nitta, N.; Wang, D.

2012-01-01

The fabrication process of crater structures on Si crystal has been studied by an irradiation of Ar beam and a thermal annealing at 600 °C. The fabricated surface was measured by field emission scanning electron microscope and atomic force microscope. The results have shown the controllability of specifications of crater formation such as density, diameter and depth by changing two irradiation parameters, fluence and energy of Ar ions. By changing the fluence over a range of 1 ∼ 10 × 10 16 /cm 2 , we could control a density of crater 0 ∼ 39 counts/100μm 2 . By changing the energy over a range of 90 ∼ 270 keV, we could control a diameter and a depth of crater in 0.8 ∼ 4.1μm and 99 ∼ 229nm, respectively. The present result is consistent with the previously proposed model that the crater structure would be arising from an exfoliated surface layer of silicon. The present result has indicated the possibility of the crater production phenomena as a hopeful method to fabricate the surface pattern on a micro-nano meter scale.

Compensation techniques in NIRS proton beam radiotherapy

International Nuclear Information System (INIS)

Akanuma, A.; Majima, H.; Furukawa, S.

1982-01-01

Proton beam has the dose distribution advantage in radiation therapy, although it has little advantage in biological effects. One of the best advantages is its sharp fall off of dose after the peak. With proton beam, therefore, the dose can be given just to cover a target volume and potentially no dose is delivered thereafter in the beam direction. To utilize this advantage, bolus techniques in conjunction with CT scanning are employed in NIRS proton beam radiation therapy planning. A patient receives CT scanning first so that the target volume can be clearly marked and the radiation direction and fixation method can be determined. At the same time bolus dimensions are calculated. The bolus frames are made with dental paraffin sheets according to the dimensions. The paraffin frame is replaced with dental resin. Alginate (a dental impression material with favorable physical density and skin surface contact) is now employed for the bolus material. With fixation device and bolus on, which are constructed individually, the patient receives CT scanning again prior to a proton beam treatment in order to prove the devices are suitable. Alginate has to be poured into the frame right before each treatments. Further investigations are required to find better bolus materials and easier construction methods

Compensation techniques in NIRS proton beam radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Akanuma, A. (Univ. of Tokyo, Japan); Majima, H.; Furukawa, S.

1982-09-01

Proton beam has the dose distribution advantage in radiation therapy, although it has little advantage in biological effects. One of the best advantages is its sharp fall off of dose after the peak. With proton beam, therefore, the dose can be given just to cover a target volume and potentially no dose is delivered thereafter in the beam direction. To utilize this advantage, bolus techniques in conjunction with CT scanning are employed in NIRS proton beam radiation therapy planning. A patient receives CT scanning first so that the target volume can be clearly marked and the radiation direction and fixation method can be determined. At the same time bolus dimensions are calculated. The bolus frames are made with dental paraffin sheets according to the dimensions. The paraffin frame is replaced with dental resin. Alginate (a dental impression material with favorable physical density and skin surface contact) is now employed for the bolus material. With fixation device and bolus on, which are constructed individually, the patient receives CT scanning again prior to a proton beam treatment in order to prove the devices are suitable. Alginate has to be poured into the frame right before each treatments. Further investigations are required to find better bolus materials and easier construction methods.

Quantitative approach for optimizing e-beam condition of photoresist inspection and measurement

Science.gov (United States)

Lin, Chia-Jen; Teng, Chia-Hao; Cheng, Po-Chung; Sato, Yoshishige; Huang, Shang-Chieh; Chen, Chu-En; Maruyama, Kotaro; Yamazaki, Yuichiro

2018-03-01

Severe process margin in advanced technology node of semiconductor device is controlled by e-beam metrology system and e-beam inspection system with scanning electron microscopy (SEM) image. By using SEM, larger area image with higher image quality is required to collect massive amount of data for metrology and to detect defect in a large area for inspection. Although photoresist is the one of the critical process in semiconductor device manufacturing, observing photoresist pattern by SEM image is crucial and troublesome especially in the case of large image. The charging effect by e-beam irradiation on photoresist pattern causes deterioration of image quality, and it affect CD variation on metrology system and causes difficulties to continue defect inspection in a long time for a large area. In this study, we established a quantitative approach for optimizing e-beam condition with "Die to Database" algorithm of NGR3500 on photoresist pattern to minimize charging effect. And we enhanced the performance of measurement and inspection on photoresist pattern by using optimized e-beam condition. NGR3500 is the geometry verification system based on "Die to Database" algorithm which compares SEM image with design data [1]. By comparing SEM image and design data, key performance indicator (KPI) of SEM image such as "Sharpness", "S/N", "Gray level variation in FOV", "Image shift" can be retrieved. These KPIs were analyzed with different e-beam conditions which consist of "Landing Energy", "Probe Current", "Scanning Speed" and "Scanning Method", and the best e-beam condition could be achieved with maximum image quality, maximum scanning speed and minimum image shift. On this quantitative approach of optimizing e-beam condition, we could observe dependency of SEM condition on photoresist charging. By using optimized e-beam condition, measurement could be continued on photoresist pattern over 24 hours stably. KPIs of SEM image proved image quality during measurement and

Intermediate Frequency Digital Receiver Based on Multi-FPGA System

Directory of Open Access Journals (Sweden)

Chengchang Zhang

2016-01-01

Full Text Available Aiming at high-cost, large-size, and inflexibility problems of traditional analog intermediate frequency receiver in the aerospace telemetry, tracking, and command (TTC system, we have proposed a new intermediate frequency (IF digital receiver based on Multi-FPGA system in this paper. Digital beam forming (DBF is realized by coordinated rotation digital computer (CORDIC algorithm. An experimental prototype has been developed on a compact Multi-FPGA system with three FPGAs to receive 16 channels of IF digital signals. Our experimental results show that our proposed scheme is able to provide a great convenience for the design of IF digital receiver, which offers a valuable reference for real-time, low power, high density, and small size receiver design.

Beam-gas Background Observations at LHC

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00214737; The ATLAS collaboration; Alici, Andrea; Lazic, Dragoslav-Laza; Alemany Fernandez, Reyes; Alessio, Federico; Bregliozzi, Giuseppe; Burkhardt, Helmut; Corti, Gloria; Guthoff, Moritz; Manousos, Athanasios; Sjoebaek, Kyrre; D'Auria, Saverio

2017-01-01

Observations of beam-induced background at LHC during 2015 and 2016 are presented in this paper. The four LHC experiments use the non-colliding bunches present in the physics-filling pattern of the accelerator to trigger on beam-gas interactions. During luminosity production the LHC experiments record the beam-gas interactions using dedicated background monitors. These data are sent to the LHC control system and are used to monitor the background levels at the experiments during accelerator operation. This is a very important measurement, since poor beam-induced background conditions can seriously affect the performance of the detectors. A summary of the evolution of the background levels during 2015 and 2016 is given in these proceedings.

Selected topics on surface effects in fusion devices: neutral-beam injectors and beam-direct converters

International Nuclear Information System (INIS)

Kaminsky, M.

1978-01-01

Neutral-beam injectors are being used for the heating and fueling of plasmas in existing devices such as PLT (Princeton), ISX (Oak Ridge) and 2XIIB (Lawrence Livermore Laboratory) and will be used in devices such as TFTR (Princeton), MX (Livermore) and Doublet III (Gulf Atomic). For example, TFTR has been designed to receive a total of 20 MW of 120-keV deuterium atoms in pulses of 0.5-sec duration from 12 neutral beam injectors; for the MX experiment it is planned to inject a total of 750A (equivalent) of deuterium atoms with a mean energy of 56 keV in 0.5-sec pulses. The interaction of energetic deuterium atoms with exposed surfaces of device components such as beam dumps, beam-direct-convertors collectors, beam calorimeters, and armor plates, cause a variety of surface effects which affect deleteriously the operation of such devices. Some of the major effects will be discussed

Laser-driven acceleration with Bessel beam

International Nuclear Information System (INIS)

Imasaki, Kazuo; Li, Dazhi

2005-01-01

A new approach of laser-driven acceleration with Bessel beam is described. Bessel beam, in contrast to the Gaussian beam, shows diffraction-free'' characteristics in its propagation, which implies potential in laser-driven acceleration. But a normal laser, even if the Bessel beam, laser can not accelerate charged particle efficiently because the difference of velocity between the particle and photon makes cyclic acceleration and deceleration phase. We proposed a Bessel beam truncated by a set of annular slits those makes several special regions in its travelling path, where the laser field becomes very weak and the accelerated particles are possible to receive no deceleration as they undergo decelerating phase. Thus, multistage acceleration is realizable with high gradient. In a numerical computation, we have shown the potential of multistage acceleration based on a three-stage model. (author)

Beam-Forming Concentrating Solar Thermal Array Power Systems

Science.gov (United States)

Cwik, Thomas A. (Inventor); Dimotakis, Paul E. (Inventor); Hoppe, Daniel J. (Inventor)

2016-01-01

The present invention relates to concentrating solar-power systems and, more particularly, beam-forming concentrating solar thermal array power systems. A solar thermal array power system is provided, including a plurality of solar concentrators arranged in pods. Each solar concentrator includes a solar collector, one or more beam-forming elements, and one or more beam-steering elements. The solar collector is dimensioned to collect and divert incoming rays of sunlight. The beam-forming elements intercept the diverted rays of sunlight, and are shaped to concentrate the rays of sunlight into a beam. The steering elements are shaped, dimensioned, positioned, and/or oriented to deflect the beam toward a beam output path. The beams from the concentrators are converted to heat at a receiver, and the heat may be temporarily stored or directly used to generate electricity.

Development of a beam ion velocity detector for the heavy ion beam probe

International Nuclear Information System (INIS)

Fimognari, P. J.; Crowley, T. P.; Demers, D. R.

2016-01-01

In an axisymmetric plasma, the conservation of canonical angular momentum constrains heavy ion beam probe (HIBP) trajectories such that measurement of the toroidal velocity component of secondary ions provides a localized determination of the poloidal flux at the volume where they originated. We have developed a prototype detector which is designed to determine the beam angle in one dimension through the detection of ion current landing on two parallel planes of detecting elements. A set of apertures creates a pattern of ion current on wires in the first plane and solid metal plates behind them; the relative amounts detected by the wires and plates determine the angle which beam ions enter the detector, which is used to infer the toroidal velocity component. The design evolved from a series of simulations within which we modeled ion beam velocity changes due to equilibrium and fluctuating magnetic fields, along with the ion beam profile and velocity dispersion, and studied how these and characteristics such as the size, cross section, and spacing of the detector elements affect performance.

Development of a beam ion velocity detector for the heavy ion beam probe

Energy Technology Data Exchange (ETDEWEB)

Fimognari, P. J., E-mail: PJFimognari@XanthoTechnologies.com; Crowley, T. P.; Demers, D. R. [Xantho Technologies, LLC, Madison, Wisconsin 53705 (United States)

2016-11-15

In an axisymmetric plasma, the conservation of canonical angular momentum constrains heavy ion beam probe (HIBP) trajectories such that measurement of the toroidal velocity component of secondary ions provides a localized determination of the poloidal flux at the volume where they originated. We have developed a prototype detector which is designed to determine the beam angle in one dimension through the detection of ion current landing on two parallel planes of detecting elements. A set of apertures creates a pattern of ion current on wires in the first plane and solid metal plates behind them; the relative amounts detected by the wires and plates determine the angle which beam ions enter the detector, which is used to infer the toroidal velocity component. The design evolved from a series of simulations within which we modeled ion beam velocity changes due to equilibrium and fluctuating magnetic fields, along with the ion beam profile and velocity dispersion, and studied how these and characteristics such as the size, cross section, and spacing of the detector elements affect performance.

Polarization properties of linearly polarized parabolic scaling Bessel beams

Energy Technology Data Exchange (ETDEWEB)

Guo, Mengwen; Zhao, Daomu, E-mail: zhaodaomu@yahoo.com

2016-10-07

The intensity profiles for the dominant polarization, cross polarization, and longitudinal components of modified parabolic scaling Bessel beams with linear polarization are investigated theoretically. The transverse intensity distributions of the three electric components are intimately connected to the topological charge. In particular, the intensity patterns of the cross polarization and longitudinal components near the apodization plane reflect the sign of the topological charge. - Highlights: • We investigated the polarization properties of modified parabolic scaling Bessel beams with linear polarization. • We studied the evolution of transverse intensity profiles for the three components of these beams. • The intensity patterns of the cross polarization and longitudinal components can reflect the sign of the topological charge.

Polarized Uniform Linear Array System: Beam Radiation Pattern, Beamforming Diversity Order, and Channel Capacity

Directory of Open Access Journals (Sweden)

Xin Su

2015-01-01

Full Text Available There have been many studies regarding antenna polarization; however, there have been few publications on the analysis of the channel capacity for polarized antenna systems using the beamforming technique. According to Chung et al., the channel capacity is determined by the density of scatterers and the transmission power, which is obtained based on the assumption that scatterers are uniformly distributed on a 3D spherical scattering model. However, it contradicts the practical scenario, where scatterers may not be uniformly distributed under outdoor environment, and lacks the consideration of fading channel gain. In this study, we derive the channel capacity of polarized uniform linear array (PULA systems using the beamforming technique in a practical scattering environment. The results show that, for PULA systems, the channel capacity, which is boosted by beamforming diversity, can be determined using the channel gain, beam radiation pattern, and beamforming diversity order (BDO, where the BDO is dependent on the antenna characteristics and array configurations.

Sub-micrometer-scale patterning on Zr-based metallic glass using focused ion beam irradiation and chemical etching

Energy Technology Data Exchange (ETDEWEB)

Kawasegi, Noritaka [Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Morita, Noboru [Graduate School of Science and Engineering for Research, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Yamada, Shigeru [Graduate School of Science and Engineering for Research, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Takano, Noboru [Graduate School of Science and Engineering for Research, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Oyama, Tatsuo [Department of Mechanical and Intellectual Systems Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Ashida, Kiwamu [Advanced Manufacturing Research Institute, National Institute of Advanced Industrial Science and Technology, 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564 (Japan); Momota, Sadao [Department of Intelligent Mechanical Systems Engineering, Kochi University of Technology, 185 Tosayamada, Kochi 782-8502 (Japan); Taniguchi, Jun [Department of Applied Electronics, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan); Miyamoto, Iwao [Department of Applied Electronics, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan); Ofune, Hitoshi [YKK Corporation, 200 Yoshida, Kurobe, Toyama 938-8601 (Japan)

2007-09-19

This report describes a method of sub-micrometer-scale rapid patterning on a Zr-based metallic glass surface using a combination of focused ion beam irradiation and wet chemical etching. We found that a Zr-based metallic glass surface irradiated with Ga{sup +} ions could be selectively etched; a concave structure with a width and depth of several tens to hundreds of nanometers rapidly formed in the irradiated area. Moreover, we determined that the etching was enhanced by the presence of Ga{sup +} ions rather than a change in the crystal structure, and the structure could be fabricated while the substrate remained amorphous. The shape of the structure was principally a function of the dose and the etch time.

Summary and Conclusions of the 'JRA Beam Telescope 2025'-Forum at the 6th Beam Telescopes and Test Beams Workshop arXiv

CERN Document Server

Dreyling-Eschweiler, J.; Amjad, M.S.; Arling, J.-H.; Coates, T.; Dätwyler, A.; Dannheim, D.; van Dijk, M.W. U.; Eichhorn, T.; Gerbershagen, A.; Girard, O.; Gkotse, B.; Iguaz, F.J.; Kroll, J.; Ravotti, F.; Rossi, E.; Rummler, A.; Salvatore, F.; Spannagel, S.; Weers, M.; Weingarten, J.

On January 17th 2018, a forum on a possible Joint Research Activity on a future common Beam Telescope was held during the 6th Beam Telescopes and Test Beams Workshop (BTTB) in Zurich, Switzerland. The BTTB workshop aims at bringing together the community involved in beam tests. It therefore offers a suitable platform to induce community-wide discussions. The forum and its discussions were well received and the participants concluded that appropriate actions should be undertaken promptly. Specific hardware and software proposals were discussed, with an emphasis on improving current common EUDET-type telescopes based on Mimosa26 sensors towards higher trigger rate capabilities in convolution with considerably improved time resolution. EUDAQ as a common top level DAQ and its modular structure is ready for future hardware. EUTelescope fulfils many requirements of a common reconstruction framework, but has also various drawbacks. Thus, requirements for a new common reconstruction framework were collected. A new co...

Selective Adsorption of Nano-bio materials and nanostructure fabrication on Molecular Resists Modified by proton beam irradiation

International Nuclear Information System (INIS)

Lee, H. W.; Kim, H. S.; Kim, S. M.

2008-04-01

The purpose of this research is the fabrication of nanostructures on silicon substrate using proton beam and selectively adsorption of bio-nano materials on the patterned substrate. Recently, the miniaturization of the integrated devices with fine functional structures was intensively investigated, based on combination of nanotechnology (NT), biotechnology (BT) and information technology (IT). Because of the inherent limitation in optical lithography, large variety of novel patterning technologies were evolved to construct nano-structures onto a substrate. Atomic force microscope-based nanolithography has readily formed sub-50 nm patterns by the local modification of a substrate using a probe with a curvature of 10 nm. The surface property was regarded as one of the most important factors for AFM-based nanolithography as well as for other novel nanolithographies. The molecular thin films such as a self-assembled monolayer or a polymer resist layer have been used as an alternative to modifying the surface property. Although proton or ion beam irradiation has been used as an efficient tool to modify the physical, chemical and electrical properties of a surface, the nano-patterning on the substrate or the molecular film modified with the beam irradiation has hardly been studied at both home and abroad. The selective adsorption of nano-bio materials such as carbon nanotubes and proteins on the patterns would contribute to developing the integrated devices. The polystyrene nanoparticles (400 nm) were arrayed on al silicon surface using nanosphere lithography and the various nanopatterns were fabricated by proton beam irradiation on the polystyrene nanoparticles arrayed silicon surface. We obtained the two different nanopatterns such as polymer nanoring patterns and silicon oxide patterns on the same silicon substrate. The polymer nanoring patterns formed by the crosslinkage of polystyrene when proton beam was irradiated at the triangular void spaces that are enclosed by

Intra–cavity generation of Bessel–like beams with longitudinally dependent cone angles

CSIR Research Space (South Africa)

Litvin, IA

2010-02-01

Full Text Available The authors report on two resonator systems for producing Bessel–like beams with longitudinally dependent cone angles (LDBLBs). Such beams have extended propagation distances as compared to conventional Bessel– Gauss beams, with a far field pattern...

Efficacy and safety of a low-level laser device in the treatment of male and female pattern hair loss: a multicenter, randomized, sham device-controlled, double-blind study.

Science.gov (United States)

Jimenez, Joaquin J; Wikramanayake, Tongyu C; Bergfeld, Wilma; Hordinsky, Maria; Hickman, Janet G; Hamblin, Michael R; Schachner, Lawrence A

2014-04-01

Male and female pattern hair loss are common, chronic dermatologic disorders with limited therapeutic options. In recent years, a number of commercial devices using low-level laser therapy have been promoted, but there have been little peer-reviewed data on their efficacy. To determine whether treatment with a low-level laser device, the US FDA-cleared HairMax Lasercomb®, increases terminal hair density in both men and women with pattern hair loss. Randomized, sham device-controlled, double-blind clinical trials were conducted at multiple institutional and private practices. A total of 146 male and 188 female subjects with pattern hair loss were screened. A total of 128 male and 141 female subjects were randomized to receive either a lasercomb (one of three models) or a sham device in concealed sealed packets, and were treated on the whole scalp three times a week for 26 weeks. Terminal hair density of the target area was evaluated at baseline and at 16- and 26-week follow-ups, and analyzed to determine whether the hypothesis formulated prior to data collection, that lasercomb treatment would increase terminal hair density, was correct. The site investigators and the subjects remained blinded to the type of device they dispensed/received throughout the study. The evaluator of masked digital photographs was blinded to which trial arm the subject belonged. Seventy-eight, 63, 49, and 79 subjects were randomized in four trials of 9-beam lasercomb treatment in female subjects, 12-beam lasercomb treatment in female subjects, 7-beam lasercomb treatment in male subjects, and 9- and 12-beam lasercomb treatment in male subjects, compared with the sham device, respectively. Nineteen female and 25 male subjects were lost to follow-up. Among the remaining 122 female and 103 male subjects in the efficacy analysis, the mean terminal hair count at 26 weeks increased from baseline by 20.2, 20.6, 18.4, 20.9, and 25.7 per cm2 in 9-beam lasercomb-treated female subjects, 12-beam

Magnetic antenna excitation of whistler modes. IV. Receiving antennas and reciprocity

Energy Technology Data Exchange (ETDEWEB)

Stenzel, R. L., E-mail: stenzel@physics.ucla.edu; Urrutia, J. M. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States)

2015-07-15

Antenna radiation patterns are an important property of antennas. Reciprocity holds in free space and the radiation patterns for exciting and receiving antennas are the same. In anisotropic plasmas, radiation patterns are complicated by the fact that group and phase velocities differ and certain wave properties like helicity depend on the direction of wave propagation with respect to the background magnetic field B{sub 0}. Interference and wave focusing effects are different than in free space. Reciprocity does not necessarily hold in a magnetized plasma. The present work considers the properties of various magnetic antennas used for receiving whistler modes. It is based on experimental data from exciting low frequency whistler modes in a large uniform laboratory plasma. By superposition of linear waves from different antennas, the radiation patterns of antenna arrays are derived. Plane waves are generated and used to determine receiving radiation patterns of different receiving antennas. Antenna arrays have radiation patterns with narrow lobes, whose angular position can be varied by physical rotation or electronic phase shifting. Reciprocity applies to broadside antenna arrays but not to end fire arrays which can have asymmetric lobes with respect to B{sub 0}. The effect of a relative motion between an antenna and the plasma has been modeled by the propagation of a short wave packet moving along a linear antenna array. An antenna moving across B{sub 0} has a radiation pattern characterized by an oscillatory “whistler wing.” A receiving antenna in motion can detect any plane wave within the group velocity resonance cone. The radiation pattern also depends on loop size relative to the wavelength. Motional effects prevent reciprocity. The concept of the radiation pattern loses its significance for wave packets since the received signal does not only depend on the antenna but also on the properties of the wave packet. The present results are of fundamental

Magnetic antenna excitation of whistler modes. IV. Receiving antennas and reciprocity

International Nuclear Information System (INIS)

Stenzel, R. L.; Urrutia, J. M.

2015-01-01

Antenna radiation patterns are an important property of antennas. Reciprocity holds in free space and the radiation patterns for exciting and receiving antennas are the same. In anisotropic plasmas, radiation patterns are complicated by the fact that group and phase velocities differ and certain wave properties like helicity depend on the direction of wave propagation with respect to the background magnetic field B 0 . Interference and wave focusing effects are different than in free space. Reciprocity does not necessarily hold in a magnetized plasma. The present work considers the properties of various magnetic antennas used for receiving whistler modes. It is based on experimental data from exciting low frequency whistler modes in a large uniform laboratory plasma. By superposition of linear waves from different antennas, the radiation patterns of antenna arrays are derived. Plane waves are generated and used to determine receiving radiation patterns of different receiving antennas. Antenna arrays have radiation patterns with narrow lobes, whose angular position can be varied by physical rotation or electronic phase shifting. Reciprocity applies to broadside antenna arrays but not to end fire arrays which can have asymmetric lobes with respect to B 0 . The effect of a relative motion between an antenna and the plasma has been modeled by the propagation of a short wave packet moving along a linear antenna array. An antenna moving across B 0 has a radiation pattern characterized by an oscillatory “whistler wing.” A receiving antenna in motion can detect any plane wave within the group velocity resonance cone. The radiation pattern also depends on loop size relative to the wavelength. Motional effects prevent reciprocity. The concept of the radiation pattern loses its significance for wave packets since the received signal does not only depend on the antenna but also on the properties of the wave packet. The present results are of fundamental interest and of

Projecting light beams with 3D waveguide arrays

Science.gov (United States)

Crespi, Andrea; Bragheri, Francesca

2017-01-01

Free-space light beams with complex intensity patterns, or non-trivial phase structure, are demanded in diverse fields, ranging from classical and quantum optical communications, to manipulation and imaging of microparticles and cells. Static or dynamic spatial light modulators, acting on the phase or intensity of an incoming light wave, are the conventional choices to produce beams with such non-trivial characteristics. However, interfacing these devices with optical fibers or integrated optical circuits often requires difficult alignment or cumbersome optical setups. Here we explore theoretically and with numerical simulations the potentialities of directly using the output of engineered three-dimensional waveguide arrays, illuminated with linearly polarized light, to project light beams with peculiar structures. We investigate through a collection of illustrative configurations the far field distribution, showing the possibility to achieve orbital angular momentum, or to produce elaborate intensity or phase patterns with several singularity points. We also simulate the propagation of the projected beam, showing the possibility to concentrate light. We note that these devices should be at reach of current technology, thus perspectives are open for the generation of complex free-space optical beams from integrated waveguide circuits.

Spectroscopic determination of species and divergence of hydrogen beams in the W7AS neutral beam injectors

International Nuclear Information System (INIS)

Ott, W.; Penningsfeld, F.P.

1993-01-01

Light-collecting systems are installed at the neutralizers of the W7AS neutral beam lines. They receive light emitted at an angle of 120 to the beam axes. Hydrogen beams are analyzed at around the wavelength of H α (6562.8 A), helium beams at around 5875.6 A. The hydrogen spectra show the well-known shifted and unshifted lines emitted by the different beam species and the background gas. The line widths are mainly determined by the beam focussing, the beamlet divergence and the apparatus profile. Knowing the focussing properties of the ion source and the instrument function of the spectrometer, one can determine the beamlet divergence. The spectrum is approximated by a series of Gaussians using least-squares fitting methods and evaluated with respect to beam species and divergence. Evaluation of the spectra proved difficult because they show a structured background, which is observed in the whole range of the Doppler shift. It is shown with helium beams that the background is caused by wall reflection of light emitted by the beam in the whole angular range between 0 and 180 . The knowledge of the background structure gained with He beams allows interpretation of the more complicated hydrogen spectra. (orig.)

Transverse phase space mapping of relativistic electron beams using optical transition radiation

Directory of Open Access Journals (Sweden)

G. P. Le Sage

1999-12-01

Full Text Available Optical transition radiation (OTR has proven to be a versatile and effective diagnostic for measuring the profile, divergence, and emittance of relativistic electron beams with a wide range of parameters. Diagnosis of the divergence of modern high brightness beams is especially well suited to OTR interference (OTRI techniques, where multiple dielectric or metal foils are used to generate a spatially coherent interference pattern. Theoretical analysis of measured OTR and OTRI patterns allows precise measurement of electron beam emittance characteristics. Here we describe an extension of this technique to allow mapping of divergence characteristics as a function of transverse coordinates within a measured beam. We present the first experimental analysis of the transverse phase space of an electron beam using all optical techniques. Comparing an optically masked portion of the beam to the entire beam, we measure different angular spread and average direction of the particles. Direct measurement of the phase-space ellipse tilt angle has been demonstrated using this optical masking technique.

Simulations and measurements of beam loss patterns at the CERN Large Hadron Collider

Science.gov (United States)

Bruce, R.; Assmann, R. W.; Boccone, V.; Bracco, C.; Brugger, M.; Cauchi, M.; Cerutti, F.; Deboy, D.; Ferrari, A.; Lari, L.; Marsili, A.; Mereghetti, A.; Mirarchi, D.; Quaranta, E.; Redaelli, S.; Robert-Demolaize, G.; Rossi, A.; Salvachua, B.; Skordis, E.; Tambasco, C.; Valentino, G.; Weiler, T.; Vlachoudis, V.; Wollmann, D.

2014-08-01

The CERN Large Hadron Collider (LHC) is designed to collide proton beams of unprecedented energy, in order to extend the frontiers of high-energy particle physics. During the first very successful running period in 2010-2013, the LHC was routinely storing protons at 3.5-4 TeV with a total beam energy of up to 146 MJ, and even higher stored energies are foreseen in the future. This puts extraordinary demands on the control of beam losses. An uncontrolled loss of even a tiny fraction of the beam could cause a superconducting magnet to undergo a transition into a normal-conducting state, or in the worst case cause material damage. Hence a multistage collimation system has been installed in order to safely intercept high-amplitude beam protons before they are lost elsewhere. To guarantee adequate protection from the collimators, a detailed theoretical understanding is needed. This article presents results of numerical simulations of the distribution of beam losses around the LHC that have leaked out of the collimation system. The studies include tracking of protons through the fields of more than 5000 magnets in the 27 km LHC ring over hundreds of revolutions, and Monte Carlo simulations of particle-matter interactions both in collimators and machine elements being hit by escaping particles. The simulation results agree typically within a factor 2 with measurements of beam loss distributions from the previous LHC run. Considering the complex simulation, which must account for a very large number of unknown imperfections, and in view of the total losses around the ring spanning over 7 orders of magnitude, we consider this an excellent agreement. Our results give confidence in the simulation tools, which are used also for the design of future accelerators.

Simulations and measurements of beam loss patterns at the CERN Large Hadron Collider

Directory of Open Access Journals (Sweden)

R. Bruce

2014-08-01

Full Text Available The CERN Large Hadron Collider (LHC is designed to collide proton beams of unprecedented energy, in order to extend the frontiers of high-energy particle physics. During the first very successful running period in 2010–2013, the LHC was routinely storing protons at 3.5–4 TeV with a total beam energy of up to 146 MJ, and even higher stored energies are foreseen in the future. This puts extraordinary demands on the control of beam losses. An uncontrolled loss of even a tiny fraction of the beam could cause a superconducting magnet to undergo a transition into a normal-conducting state, or in the worst case cause material damage. Hence a multistage collimation system has been installed in order to safely intercept high-amplitude beam protons before they are lost elsewhere. To guarantee adequate protection from the collimators, a detailed theoretical understanding is needed. This article presents results of numerical simulations of the distribution of beam losses around the LHC that have leaked out of the collimation system. The studies include tracking of protons through the fields of more than 5000 magnets in the 27 km LHC ring over hundreds of revolutions, and Monte Carlo simulations of particle-matter interactions both in collimators and machine elements being hit by escaping particles. The simulation results agree typically within a factor 2 with measurements of beam loss distributions from the previous LHC run. Considering the complex simulation, which must account for a very large number of unknown imperfections, and in view of the total losses around the ring spanning over 7 orders of magnitude, we consider this an excellent agreement. Our results give confidence in the simulation tools, which are used also for the design of future accelerators.

Radiation monitoring and beam dump system of the OPAL silicon microvertex detector

CERN Document Server

Braibant, S

1997-01-01

The OPAL microvertex silicon detector radiation monitoring and beam dump system is described. This system was designed and implemented in order to measure the radiation dose received at every beam crossing and to induce a fast beam dump if the radiation dose exceeds a given threshold.

Collimator for the SPS extracted beam

CERN Multimedia

CERN PhotoLab

1976-01-01

This is a water cooled copper collimator (TCSA) which has exactly the shape of the cross section of the downstream magnetic beam splitter. Parts of the blown up primary proton beam pass above/below and left through this collimator. A small part of the protons is absorbed in the thin copper wedges. In this way the downstream magnetic splitter of the same cross section receives already a beam where its magnetic wedges are no longer hit by protons. The upstream, water cooled collimator, more resistant to protons, has cast a 'shadow' onto the downstream magnetic splitter, less resistant to protons. Gualtero Del Torre stands on the left.

Off-Axis Gaussian Beams with Random Displacement in Atmospheric Turbulence

Directory of Open Access Journals (Sweden)

Yahya Baykal

2006-10-01

Full Text Available Our recent work in which we study the propagation of the general Hermite-sinusoidal-Gaussian laser beams in wireless broadband access telecommunication systems is elaborated in this paper to cover the special case of an off-axis Gaussian beam. We mainly investigate the propagation characteristics in atmospheric turbulence of an off-axis Gaussian beam possessing Gaussian distributed random displacement parameters. Our interest is to search for different types of laser beams that will improve the performance of a wireless broadband access system when atmospheric turbulence is considered. Our formulation is based on the basic solution of the second order mutual coherence function evaluated at the receiver plane. For fixed turbulence strength, the coherence length calculated at the receiver plane is found to decrease as the variance of the random displacement is increased. It is shown that as the turbulence becomes stronger, coherence lengths due to off-axis Gaussian beams tend to approach the same value, irrespective of the variance of the random displacement. As expected, the beam spreading is found to be pronounced for larger variance of displacement parameter. Average intensity profiles when atmospheric turbulence is present are plotted for different values of the variance of the random displacement parameter of the off-axis Gaussian beam.

Customizable Digital Receivers for Radar

Science.gov (United States)

Moller, Delwyn; Heavey, Brandon; Sadowy, Gregory

2008-01-01

Compact, highly customizable digital receivers are being developed for the system described in 'Radar Interferometer for Topographic Mapping of Glaciers and Ice Sheets' (NPO-43962), NASA Tech Briefs, Vol. 31, No. 7 (August 2007), page 72. The receivers are required to operate in unison, sampling radar returns received by the antenna elements in a digital beam-forming (DBF) mode. The design of these receivers could also be adapted to commercial radar systems. At the time of reporting the information for this article, there were no commercially available digital receivers capable of satisfying all of the operational requirements and compact enough to be mounted directly on the antenna elements. A provided figure depicts the overall system of which the digital receivers are parts. Each digital receiver includes an analog-to-digital converter (ADC), a demultiplexer (DMUX), and a field-programmable gate array (FPGA). The ADC effects 10-bit band-pass sampling of input signals having frequencies up to 3.5 GHz. The input samples are demultiplexed at a user-selectable rate of 1:2 or 1:4, then buffered in part of the FPGA that functions as a first-in/first-out (FIFO) memory. Another part of the FPGA serves as a controller for the ADC, DMUX, and FIFO memory and as an interface between (1) the rest of the receiver and (2) a front-panel data port (FPDP) bus, which is an industry-standard parallel data bus that has a high data-rate capability and multichannel configuration suitable for DBF. Still other parts of the FPGA in each receiver perform signal-processing functions. The digital receivers can be configured to operate in a stand-alone mode, or in a multichannel mode as needed for DBF. The customizability of the receiver makes it applicable to a broad range of system architectures. The capability for operation of receivers in either a stand-alone or a DBF mode enables the use of the receivers in an unprecedentedly wide variety of radar systems.

Electron beam-induced structural transformations of MoO{sub 3} and MoO{sub 3-x} crystalline nanostructures

Energy Technology Data Exchange (ETDEWEB)

Diaz-Droguett, D. E., E-mail: dodiaz@fis.puc.cl [Pontificia Universidad Catolica de Chile, Departamento de Fisica, Facultad de Fisica (Chile); Zuniga, A. [Universidad de Chile, Departamento de Ingenieria Mecanica, Facultad de Ciencias Fisicas y Matematicas (Chile); Solorzano, G. [PUC-RIO, Departamento de Ciencia dos Materiais e Metalurgia, DCMM (Brazil); Fuenzalida, V. M. [Universidad de Chile, Departamento de Fisica, Facultad de Ciencias Fisicas y Matematicas (Chile)

2012-01-15

Electron beam-induced damage and structural changes in MoO{sub 3} and MoO{sub 3-x} single crystalline nanostructures were revealed by in situ transmission electron microscopy (TEM) examination (at 200 kV) after few minutes of concentrating the electron beam onto small areas (diameters between 25 and 200 nm) of the samples. The damage was evaluated recording TEM images, while the structural changes were revealed acquiring selected area electron diffraction patterns and high resolution transmission electron microscopy (HRTEM) images after different irradiation times. The as-received nanostructures of orthorhombic MoO{sub 3} were transformed to a Magneli's phase of the oxide ({gamma}-Mo{sub 4}O{sub 11}) after {approx}10 min of electron beam irradiation. The oxygen loss from the oxide promoted structural changes. HRTEM observations showed that, in the first stage of the reduction, oxygen vacancies generated by the electron beam are accommodated by forming crystallographic shear planes. At a later stage of the reduction process, a polycrystalline structure was developed with highly oxygen-deficient grains. The structural changes can be attributed to the local heating of the irradiated zone combined with radiolysis.

Radiation pattern synthesis of planar antennas using the iterative sampling method

Science.gov (United States)

Stutzman, W. L.; Coffey, E. L.

1975-01-01

A synthesis method is presented for determining an excitation of an arbitrary (but fixed) planar source configuration. The desired radiation pattern is specified over all or part of the visible region. It may have multiple and/or shaped main beams with low sidelobes. The iterative sampling method is used to find an excitation of the source which yields a radiation pattern that approximates the desired pattern to within a specified tolerance. In this paper the method is used to calculate excitations for line sources, linear arrays (equally and unequally spaced), rectangular apertures, rectangular arrays (arbitrary spacing grid), and circular apertures. Examples using these sources to form patterns with shaped main beams, multiple main beams, shaped sidelobe levels, and combinations thereof are given.

Effects of tissue inhomogeneities on dose patterns in cylinders irradiated by negative pion beams

International Nuclear Information System (INIS)

Hamm, R.N.; Wright, H.A.; Turner, J.E.

1975-10-01

Effects of the presence of inhomogeneities in tissue irradiated by negative pion beams are investigated. Soft-tissue targets are considered with embedded regions of bone and cavities of air. The absorbed dose is calculated as a function of position in the targets for parallel and converging beams and for two parallel beams that enter the target from opposite sides. Isodose contours are calculated and displayed in each case. While these studies show expected trends, they indicate that specific calculations are needed for other beam parameters and target geometries. The contributions of neutrons to the dose contours can be seen from several calculations made both with and without neutrons

Beam-Beam Effects

International Nuclear Information System (INIS)

Herr, W; Pieloni, T

2014-01-01

One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities

Beam studies with a LNB detector system

Energy Technology Data Exchange (ETDEWEB)

Schwarzkopf, Joachim; Judin, Vitali; Mueller, Anke-Susanne [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany)

2013-07-01

At ANKA, the synchrotron of the KIT (Karlsruhe Institue of Technology), beam studies with a detector system better known for its use in the entertainment industry have been carried out. The system basically consists of a LNB (Low Noise Block), usually part of a satellite TV receiver. One possible application in accelerator physics is the monitoring of the bunch length. This presentation reports on beam experiments with this inexpensive detector.

Ion beam dump for JT-60 NBI

International Nuclear Information System (INIS)

Kuriyama, Masaaki; Horiike, Hiroshi; Matsuda, Shinzaburo; Morita, Hiroaki; Shibanuma, Kiyoshi

1981-10-01

The design of the active cooling type ion beam dump for JT-60 NBI which receives the total beam power of 5.6 MW for 10 sec continuously is described. It is composed of array of many finned tubes which is made of oxygen free copper with 0.2% silver content. The safety margin against thermal and mechanical troubles is estimated by the heat transfer and the thermal stress calculation. (author)

Interference-aware random beam selection schemes for spectrum sharing systems

KAUST Repository

Abdallah, Mohamed

2012-10-19

Spectrum sharing systems have been recently introduced to alleviate the problem of spectrum scarcity by allowing secondary unlicensed networks to share the spectrum with primary licensed networks under acceptable interference levels to the primary users. In this work, we develop interference-aware random beam selection schemes that provide enhanced performance for the secondary network under the condition that the interference observed by the receivers of the primary network is below a predetermined/acceptable value. We consider a secondary link composed of a transmitter equipped with multiple antennas and a single-antenna receiver sharing the same spectrum with a primary link composed of a single-antenna transmitter and a single-antenna receiver. The proposed schemes select a beam, among a set of power-optimized random beams, that maximizes the signal-to-interference-plus-noise ratio (SINR) of the secondary link while satisfying the primary interference constraint for different levels of feedback information describing the interference level at the primary receiver. For the proposed schemes, we develop a statistical analysis for the SINR statistics as well as the capacity and bit error rate (BER) of the secondary link.

Russian institute receives CMS Gold Award

CERN Multimedia

Patrice Loïez

2003-01-01

The Snezhinsk All-Russian Institute of Scientific Research for Technical Physics (VNIITF) of the Russian Federal Nuclear Centre (RFNC) is one of twelve CMS suppliers to receive awards for outstanding performance this year. The CMS Collaboration took the opportunity of the visit to CERN of the Director of VNIITF and his deputy to present the CMS Gold Award, which the institute has received for its exceptional performance in the assembly of steel plates for the CMS forward hadronic calorimeter. This calorimeter consists of two sets of 18 wedge-shaped modules arranged concentrically around the beam-pipe at each end of the CMS detector. Each module consists of steel absorber plates with quartz fibres inserted into them. The institute developed a special welding technique to assemble the absorber plates, enabling a high-quality detector to be produced at relatively low cost.RFNC-VNIITF Director Professor Georgy Rykovanov (right), is seen here receiving the Gold Award from Felicitas Pauss, Vice-Chairman of the CMS ...

Collected abstracts on particle beam diagnostic systems

International Nuclear Information System (INIS)

Hickok, R.L.

1979-01-01

This report contains a compilation of abstracts on work related to particle beam diagnostics for high temperature plasmas. The abstracts were gathered in early 1978 and represent the status of the various programs as of that date. It is not suggested that this is a comprehensive list of all the work that is going on in the development of particle beam diagnostics, but it does provide a representative view of the work in this field. For example, no abstracts were received from the U.S.S.R. even though they have considerable activity in particle beam diagnostics

Scaling in patterns produces by cluster deposition

DEFF Research Database (Denmark)

Kyhle, Anders; Sørensen, Alexis Hammer; Oddershede, Lene

1997-01-01

Cluster deposition on flat substrates can lead to surprising patterns. This pattern formation can be related either to phenomena taking place at the substrate surface or to dynamics in the cluster beam. We describe the observation of a pattern of particles each being an aggregate of Cu clusters. ...

Beam position monitor system for storage rings

International Nuclear Information System (INIS)

Nakamura, M.; Hinkson, J.A.

1985-05-01

Beam position monitors (BPM) for synchrotron light storage rings usually consist of beam pickup electrodes, coaxial relays and a narrowband receiver. While accurate, these systems are slow and of limited use in the commissioning of an accelerator. A beam position monitor is described which is intended to be a principal diagnostic during debug and routine running of a storage ring. It is capable of measuring the position of a single bunch on the first or nth orbit to an accuracy of a few percent. Stored beam position is more accurately measured with averaging techniques. Beam position changes can be studied in a bandwidth from DC to a few MHz. The beam monitor electronics consist of a separate amplification, detection, and sampling channel for each beam pickup electrode. Fast switches in each channel permit selection of the nth turn for measurement (single bunch mode). A calibration pulse is injected into each channel after beam measurement to permit gain offsets to be measured and removed from the final data. While initially more costly than the usual beam position monitor system, this sytem will pay for itself in reduced storage ring debug and trouble shooting time. 5 refs., 5 figs

Graphene-based Yagi-Uda antenna with reconfigurable radiation patterns

Energy Technology Data Exchange (ETDEWEB)

Wu, Yongle, E-mail: wuyongle138@gmail.com; Qu, Meijun; Jiao, Lingxiao; Liu, Yuanan [School of Electronic Engineering, Beijing Key Laboratory of Work Safety Intelligent Monitoring, Beijing University of Posts and Telecommunications, P. O. Box. 282, Beijing, 100876 (China); Ghassemlooy, Zabih [Optical Communications Research Group, NCRLab, Faculty of Engineering and Environment, Northumbria University, Newcastle upon Tyne, NE1 8ST (United Kingdom)

2016-06-15

This paper presents a radiation pattern reconfigurable Yagi-Uda antenna based on graphene operating at terahertz frequencies. The antenna can be reconfigured to change the main beam pattern into two or four different radiation directions. The proposed antenna consists of a driven dipole radiation conductor, parasitic strips and embedded graphene. The hybrid graphene-metal implementation enables the antenna to have dynamic surface conductivity, which can be tuned by changing the chemical potentials. Therefore, the main beam direction, the resonance frequency, and the front-to-back ratio of the proposed antenna can be controlled by tuning the chemical potentials of the graphene embedded in different positions. The proposed two-beam reconfigurable Yagi-Uda antenna can achieve excellent unidirectional symmetrical radiation pattern with the front-to-back ratio of 11.9 dB and the10-dB impedance bandwidth of 15%. The different radiation directivity of the two-beam reconfigurable antenna can be achieved by controlling the chemical potentials of the graphene embedded in the parasitic stubs. The achievable peak gain of the proposed two-beam reconfigurable antenna is about 7.8 dB. Furthermore, we propose a four-beam reconfigurable Yagi-Uda antenna, which has stable reflection-coefficient performance although four main beams in reconfigurable cases point to four totally different directions. The corresponding peak gain, front-to-back ratio, and 10-dB impedance bandwidth of the four-beam reconfigurable antenna are about 6.4 dB, 12 dB, and 10%, respectively. Therefore, this novel design method of reconfigurable antennas is extremely promising for beam-scanning in terahertz and mid-infrared plasmonic devices and systems.

High precision patterning of ITO using femtosecond laser annealing process

International Nuclear Information System (INIS)

Cheng, Chung-Wei; Lin, Cen-Ying

2014-01-01

Highlights: • We have reported a process of fabrication of crystalline indium tin oxide (c-ITO) patterns using femtosecond laser-induced crystallization with a Gaussian beam profile followed by chemical etching. • The experimental results have demonstrated that the ablation and crystallization threshold fluences of a-ITO thin film are well-defined, the line width of the c-ITO patterns is controllable. • Fast fabrication of the two parallel sub-micro (∼0.5 μm) c-ITO line patterns using a single femtosecond laser beam and a single scanning path can be achieved. • A long-length sub-micro c-ITO line pattern is fabricated, and the feasibility of fabricating c-ITO patterns is confirmed, which are expected to be used in micro-electronics devices. - Abstract: High precision patterning of crystalline indium tin oxide (c-ITO) patterns on amorphous ITO (a-ITO) thin films by femtosecond laser-induced crystallization with a Gaussian beam profile followed by chemical etching is demonstrated. In the proposed approach, the a-ITO thin film is selectively transformed into a c-ITO structure via a low heat affect zone and the well-defined thresholds (ablation and crystallization) supplied by the femtosecond laser pulse. The experimental results show that by careful control of the laser fluence above the crystallization threshold, c-ITO patterns with controllable line widths and ridge-free characteristics can be accomplished. By careful control of the laser fluence above the ablation threshold, fast fabrication of the two parallel sub-micro c-ITO line patterns using a single femtosecond laser beam and single scanning path can be achieved. Along-length sub-micro c-ITO line pattern is fabricated, and the feasibility of fabricating c-ITO patterns is confirmed, which are expected to be used in micro-electronics devices

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....

Surface flatness measurement of quasi-parallel plates employing three-beam interference with strong reference beam

Science.gov (United States)

Sunderland, Zofia; Patorski, Krzysztof

2016-12-01

A big challenge for standard interferogram analysis methods such as Temporal Phase Shifting or Fourier Transform is a parasitic set of fringes which might occur in the analyzed fringe pattern intensity distribution. It is encountered, for example, when transparent glass plates with quasi-parallel surfaces are tested in Fizeau or Twyman-Green interferometers. Besides the beams reflected from the plate front surface and the interferometer reference the beam reflected from the plate rear surface also plays important role; its amplitude is comparable with the amplitude of other beams. In result we face three families of fringes of high contrast which cannot be easily separated. Earlier we proposed a competitive solution for flatness measurements which relies on eliminating one of those fringe sets from the three-beam interferogram and separating two remaining ones with the use of 2D Continuous Wavelet Transform. In this work we cover the case when the intensity of the reference beam is significantly higher than the intensities of two object beams. The main advantage of differentiating beam intensities is the change in contrast of individual fringe families. Processing of such three-beam interferograms is modified but also takes advantage of 2D CWT. We show how to implement this method in Twyman-Green and Fizeau setups and compare this processing path and measurement procedures with previously proposed solutions.

Ridge Minimization of Ablated Morphologies on ITO Thin Films Using Squared Quasi-Flat Top Beam

Directory of Open Access Journals (Sweden)

Hoon-Young Kim

2018-03-01

Full Text Available In this study, we explore the improvements in pattern quality that was obtained with a femtosecond laser with quasi-flat top beam profiles at the ablated edge of indium tin oxide (ITO thin films for the patterning of optoelectronic devices. To ablate the ITO thin films, a femtosecond laser is used that has a wavelength and pulse duration of 1030 nm and 190 fs, respectively. The squared quasi-flat top beam is obtained from a circular Gaussian beam using slits with varying x-y axes. Then, the patterned ITO thin films are measured using both scanning electron and atomic force microscopes. In the case of the Gaussian beam, the ridge height and width are approximately 39 nm and 1.1 μm, respectively, whereas, when the quasi-flat top beam is used, the ridge height and width are approximately 7 nm and 0.25 μm, respectively.

Nanofabrication by ion-beam sputtering fundamentals and applications

CERN Document Server

Som, Tapobrata

2012-01-01

Considerable attention has been paid to ion beam sputtering as an effective way to fabricate self-organized nano-patterns on various substrates. The significance of this method for patterning surfaces is that the technique is fast, simple, and less expensive. The possibility to create patterns on very large areas at once makes it even more attractive. This book reviews various fascinating results, understand the underlying physics of ion induced pattern formation, to highlight the potential applications of the patterned surfaces, and to explore the patterning behavior by different irradiation

Experimental investigation of complex circular Airy beam characteristics

Science.gov (United States)

Porfirev, A. P.; Fomchenkov, S. A.; Khonina, S. N.

2018-04-01

We demonstrate a new type of circular Airy beams, the so-called azimuthally modulated circular Airy beams, generated by utilizing a diffraction element, whose transmission function is the sum of the transmission function of the element generating a "petal" pattern and the transmission function of the element generating a circular Airy beam. We experimentally investigate the propagation dynamics of such beams and demonstrate that their autofocusing and selfhealing properties are strongly dependent on the number of generated petals. These beams are a combination of a conventional circular Airy beam and vortex laser beams (or their superpositions). Using a spatial light modulator, we demonstrate that these beams have unique properties such as autofocusing, "nondiffractive" propagation and self-healing after passing through an obstacle. The experimental results are in good agreement with the simulation. We believe that these results can be very useful for lensless laser fabrication and laser manipulation techniques, as well as for development of new filament plasma multi-channel formation methods.

Arc-based smoothing of ion beam intensity on targets

International Nuclear Information System (INIS)

Friedman, Alex

2012-01-01

By manipulating a set of ion beams upstream of a target, it is possible to arrange for a smoother deposition pattern, so as to achieve more uniform illumination of the target. A uniform energy deposition pattern is important for applications including ion-beam-driven high energy density physics and heavy-ion beam-driven inertial fusion energy (“heavy-ion fusion”). Here, we consider an approach to such smoothing that is based on rapidly “wobbling” each of the beams back and forth along a short arc-shaped path, via oscillating fields applied upstream of the final pulse compression. In this technique, uniformity is achieved in the time-averaged sense; this is sufficient provided the beam oscillation timescale is short relative to the hydrodynamic timescale of the target implosion. This work builds on two earlier concepts: elliptical beams applied to a distributed-radiator target [D. A. Callahan and M. Tabak, Phys. Plasmas 7, 2083 (2000)] and beams that are wobbled so as to trace a number of full rotations around a circular or elliptical path [R. C. Arnold et al., Nucl. Instrum. Methods 199, 557 (1982)]. Here, we describe the arc-based smoothing approach and compare it to results obtainable using an elliptical-beam prescription. In particular, we assess the potential of these approaches for minimization of azimuthal asymmetry, for the case of a ring of beams arranged on a cone. It is found that, for small numbers of beams on the ring, the arc-based smoothing approach offers superior uniformity. In contrast with the full-rotation approach, arc-based smoothing remains usable when the geometry precludes wobbling the beams around a full circle, e.g., for the X-target [E. Henestroza, B. G. Logan, and L. J. Perkins, Phys. Plasmas 18, 032702 (2011)] and some classes of distributed-radiator targets.

Importance of beam-beam tune spread to collective beam-beam instability in hadron colliders

International Nuclear Information System (INIS)

Jin Lihui; Shi Jicong

2004-01-01

In hadron colliders, electron-beam compensation of beam-beam tune spread has been explored for a reduction of beam-beam effects. In this paper, effects of the tune-spread compensation on beam-beam instabilities were studied with a self-consistent beam-beam simulation in model lattices of Tevatron and Large Hodron Collider. It was found that the reduction of the tune spread with the electron-beam compensation could induce a coherent beam-beam instability. The merit of the compensation with different degrees of tune-spread reduction was evaluated based on beam-size growth. When two beams have a same betatron tune, the compensation could do more harm than good to the beams when only beam-beam effects are considered. If a tune split between two beams is large enough, the compensation with a small reduction of the tune spread could benefit beams as Landau damping suppresses the coherent beam-beam instability. The result indicates that nonlinear (nonintegrable) beam-beam effects could dominate beam dynamics and a reduction of beam-beam tune spread by introducing additional beam-beam interactions and reducing Landau damping may not improve the stability of beams

A Novel Location-Awareness Method Using CubeSats for Locating the Spot Beam Emitters of Geostationary Communications Satellites

Directory of Open Access Journals (Sweden)

Weicai Yang

2018-01-01

Full Text Available As more spacecraft are launched into the Geostationary Earth Orbit (GEO belt, the possibility of fatal collisions or unnecessary interference between spacecraft increases. In this paper, a new location-awareness method that uses CubeSats is proposed to assist with radiofrequency (RF domain verification by means of awareness and identification of the positions of the spot beam emitters of communications satellites in geostationary orbit. By flying a CubeSat (or a constellation of CubeSats through the coverage area of a spot beam, the spot beam emitter’s position is identified and the spot beam’s pattern knowledge is characterized. The geometry, the equations of motion of the spacecraft, the measurement process, and the filtering equations in a location system are addressed with respect to the location methods investigated in this study. A realistic scenario in which a CubeSat receives signals from GEO communications satellites is simulated using the Systems Tool Kit (STK. The results of the simulation and the analysis presented in this study provide a thorough verification of the performance of the location-awareness method.

Novel calibration system with sparse wires for CMB polarization receivers

International Nuclear Information System (INIS)

Tajima, O.; Nguyen, H.; Bischoff, C.; Brizius, A.; Buder, I.; Kusaka, A.

2011-01-01

B-modes in the cosmic microwave background (CMB) polarization is a smoking gun signature of the inflationary universe. To achieve better sensitivity to this faint signal, CMB polarization experiments aim to maximize the number of detector elements, resulting in a large focal plane receiver. Detector calibration of the polarization response becomes essential. It is extremely useful to be able to calibrate 'simultaneously' all detectors on the large focal plane. We developed a novel calibration system that rotates a large 'sparse' grid of metal wires, in front of and fully covering the field of view of the focal plane receiver. Polarized radiation is created via the reflection of ambient temperature from the wire surface. Since the detector has a finite beam size, the observed signal is smeared according to the beam property. The resulting smeared polarized radiation has a reasonable intensity (a few Kelvin or less) compared to the sky temperature (∼10 K observing condition). The system played a successful role for receiver calibration of QUIET, a CMB polarization experiment located in the Atacama desert in Chile. The successful performance revealed that this system is applicable to other experiments based on different technologies, e.g. TES bolometers.

Generation and application of Bessel beam in alignment works

International Nuclear Information System (INIS)

Gale, D. M.

2009-01-01

The divergence of a Gaussian laser beam is a limiting factor for optical alignment tasks at large distances. Bessel beams have almost zero divergence but are still not widely used. We discuss the construction of an alignment telescope based on Bessel beam generation using a commercial laser diode module. The Bessel beam is generated with conical or plano-convex lenses, and projected using a commercial CCD camera lens to extend the useful range of the beam. Our Bessel beams have diameters of between 0.5 - 1mm over beam lengths of 15m, representing a six-fold improvement compared to Gaussian beams, while the transverse beam structure (Bessel pattern) provides an excellent alignment aid for use with beam target. Another advantage of Bessel beams is their self-regeneration property, which allows the use of multiple beam targets with minimum beam degradation. We are using our crosshair targets with crosshair targets to align optical components in a large astronomical telescope, and can achieve precisions of tens of microns over distances of 20m using purely visual methods. (Author)

Development of splitting convergent beam electron diffraction (SCBED)

Energy Technology Data Exchange (ETDEWEB)

Houdellier, Florent, E-mail: Florent.Houdellier@cemes.fr [CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse (France); Röder, Falk [CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse (France); Triebenberg Lab, Institut für Strukturphysik, Technische Universität Dresden, D-01062 Dresden (Germany); Snoeck, Etienne [CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse (France)

2015-12-15

Using a combination of condenser electrostatic biprism with dedicated electron optic conditions for sample illumination, we were able to split a convergent beam electron probe focused on the sample in two half focused probes without introducing any tilt between them. As a consequence, a combined convergent beam electron diffraction pattern is obtained in the back focal plane of the objective lens arising from two different sample areas, which could be analyzed in a single pattern. This splitting convergent beam electron diffraction (SCBED) pattern has been tested first on a well-characterized test sample of Si/SiGe multilayers epitaxially grown on a Si substrate. The SCBED pattern contains information from the strained area, which exhibits HOLZ lines broadening induced by surface relaxation, with fine HOLZ lines observed in the unstrained reference part of the sample. These patterns have been analyzed quantitatively using both parts of the SCBED transmitted disk. The fine HOLZ line positions are used to determine the precise acceleration voltage of the microscope while the perturbed HOLZ rocking curves in the stained area are compared to dynamical simulated ones. The combination of these two information leads to a precise evaluation of the sample strain state. Finally, several SCBED setups are proposed to tackle fundamental physics questions as well as applied materials science ones and demonstrate how SCBED has the potential to greatly expand the range of applications of electron diffraction and electron holography. - Highlights: • Using a condenser biprism, we split the CBED pattern in two half-CBED disks. • We have determined the electron optical conditions used to perform various SCBED. • We propose new applications possible for this new SCBED configuration.

Beam emittance measurements on multicusp ion sources

Energy Technology Data Exchange (ETDEWEB)

Sarstedt, M.; Lee, Y.; Leung, K.N. [and others

1995-08-01

Multicusp ion sources are used for various applications. Presently, the implementation of this type of ion source planned for the development of an ion beam lithography machine, which will be used for the projection of sub-0.2 {mu}m patterns onto a wafer substrate. Since, for this application, a very good beam quality and a small ion energy spread are required, emittance measurements have been performed on a multicusp ion source for various source conditions. It is shown that the installation of proper capacitors between the extraction electrodes is necessary to avoid rf-pickup, which otherwise leads to a distortion of the beam emittance. The influence of the magnetic filter field on the beam emittance has been investigated, and the beam emittance of a dc filament-discharge plasma has also been compared to that of an rf-generated plasma.

Beam emittance measurements on multicusp ion sources

International Nuclear Information System (INIS)

Sarstedt, M.; Lee, Y.; Leung, K.N.

1995-08-01

Multicusp ion sources are used for various applications. Presently, the implementation of this type of ion source planned for the development of an ion beam lithography machine, which will be used for the projection of sub-0.2 μm patterns onto a wafer substrate. Since, for this application, a very good beam quality and a small ion energy spread are required, emittance measurements have been performed on a multicusp ion source for various source conditions. It is shown that the installation of proper capacitors between the extraction electrodes is necessary to avoid rf-pickup, which otherwise leads to a distortion of the beam emittance. The influence of the magnetic filter field on the beam emittance has been investigated, and the beam emittance of a dc filament-discharge plasma has also been compared to that of an rf-generated plasma

A criterion-based audit of the technical quality of external beam radiotherapy for prostate cancer

International Nuclear Information System (INIS)

Brundage, Michael; Danielson, Brita; Pearcey, Robert; Bass, Brenda; Pickles, Tom; Bahary, Jean-Paul; Peng, Yingwei; Wallace, David; Mackillop, William

2013-01-01

Purpose: To evaluate the technical quality of external beam radiotherapy for prostate cancer in Canada. Methods: This was a multi-institution, retrospective study of a random sample of patients undergoing radiotherapy (RT) for prostate cancer in Canada. Patterns of care were determined by abstracting details of the patients’ management from original records. The quality of patient’s technical care was measured against a previously published, comprehensive suite of quality indicators. Results: 32 of the 37 RT centres participated. The total study population of 810 patients included 25% low-risk, 44% intermediate-risk, and 28% high-risk cases. 649 received external beam RT (EBRT) only, for whom compliance with 12 indicators of the quality of pre-treatment assessment ranged from 56% (sexual function documented) to 96% (staging bone scan obtained in high-risk patients). Compliance with treatment-related indicators ranged from 78% (dose to prostate ⩾74 Gy in intermediate risk patients not receiving hormone therapy) to 100% (3DCRT or IMRT plan). Compliance varied among centres; no centre demonstrated 100% compliance on all indicators and every centre was 100% compliant on at least some indicators. The number of assessment-related indicators (n = 13) with which a given centre was 100% compliant ranged from 4 to 11 (median 7) and the number of the treatment-specific indicators (n = 8) with which a given centre was 100% compliant ranged from 6 to 8 (median 8). ADT therapy was utilised in most high-risk cases (191, 92.3%). Conclusions: While patterns of prostate cancer care in Canada vary somewhat, compliance on the majority of quality indicators is very high. However, all centres showed room for improvement on several indicators and few individual patients received care that met target benchmarks on all quality measures. This variation is particularly important for indicators such as delivered dose where impact on disease outcome is known to exist, and suggests that

Proton beam writing for producing holographic images

International Nuclear Information System (INIS)

Ow, Y.S.; Breese, M.B.H.; Bettiol, A.A.

2009-01-01

This work reports on the writing of computer generated hologram diffraction patterns using focused 2 MeV proton beam irradiation. These patterns were designed using a ray tracing algorithm and written directly into a thick polymethylmethacrylate layer. When the developed holographic pattern was illuminated with a 650 nm laser it produced a good reconstructed image. This work provides means of forming high-resolution, high aspect ratio holographic images in polymers for applications in data storage using switchable holography.

Graphene crystal growth by thermal precipitation of focused ion beam induced deposition of carbon precursor via patterned-iron thin layers

Directory of Open Access Journals (Sweden)

Rius Gemma

2014-01-01

Full Text Available Recently, relevant advances on graphene as a building block of integrated circuits (ICs have been demonstrated. Graphene growth and device fabrication related processing has been steadily and intensively powered due to commercial interest; however, there are many challenges associated with the incorporation of graphene into commercial applications which includes challenges associated with the synthesis of this material. Specifically, the controlled deposition of single layer large single crystal graphene on arbitrary supports, is particularly challenging. Previously, we have reported the first demonstration of the transformation of focused ion beam induced deposition of carbon (FIBID-C into patterned graphitic layers by metal-assisted thermal treatment (Ni foils. In this present work, we continue exploiting the FIBID-C approach as a route for graphene deposition. Here, thin patterned Fe layers are used for the catalysis of graphenization and graphitization. We demonstrate the formation of high quality single and few layer graphene, which evidences, the possibility of using Fe as a catalyst for graphene deposition. The mechanism is understood as the minute precipitation of atomic carbon after supersaturation of some iron carbides formed under a high temperature treatment. As a consequence of the complete wetting of FIBID-C and patterned Fe layers, which enable graphene growth, the as-deposited patterns do not preserve their original shape after the thermal treatment

Measurement of the real time fill-pattern at the Australian Synchrotron

International Nuclear Information System (INIS)

Peake, D.J.; Boland, M.J.; LeBlanc, G.S.; Rassool, R.P.

2008-01-01

This article describes the development, commissioning and operation of a Fill-Pattern Monitor (FPM) for the Australian Synchrotron that measures the real-time intensity distribution of the electron bunches in the storage ring. Using a combination of an ultra-fast photodiode and a high-speed digitiser, real-time measurement of the fill-pattern at bunch-by-bunch resolution was achieved. The results compare very well with current methods of measuring the fill-pattern, such as a pick-up style detector. In addition, the FPM is fully integrated into the EPICS control system. The data provided by the FPM gives accurate RF bucket position and relative bunch currents over a wide range of stored beam currents, from 0.01 mA in a single bunch to 200 mA total beam current. The FPM monitors the success of an injection attempt into the storage ring and is used in a feedback loop to determine where to target the next injection. Using the FPM a beam top-up mode was successfully tested, resulting in a near constant beam current by periodic targeted injections over an 8 h shift. Results are presented for dynamically topped up real-time injection, where the beam pattern was squared using an intensity-dependent injection algorithm

GEANT4 simulation diagram showing the architecture of the ATLAS test line: the detectors are positioned to receive the beam from the SPS. A muon particle which enters the magnet and crosses all detectors is shown (blue line).

CERN Multimedia

2004-01-01

GEANT4 simulation diagram showing the architecture of the ATLAS test line: the detectors are positioned to receive the beam from the SPS. A muon particle which enters the magnet and crosses all detectors is shown (blue line).

Patterns of failure in children with medulloblastoma treated with 3D conformal radiotherapy

International Nuclear Information System (INIS)

Skowronska-Gardas, Anna; Chojnacka, Marzanna; Morawska-Kaczynska, Marzena; Perek, Danuta; Perek-Polnik, Marta

2007-01-01

Background and purpose: Craniospinal irradiation for medulloblastoma is one of the most complex techniques employed in radiotherapy. Many reports stress the impact of irradiation quality on survival in these patients. Our report presents the outcome and patterns of failure for 95 patients treated with 3D conformal radiotherapy (3D-CRT). Materials and methods: From 1998 to 2003, 95 children with medulloblastoma received 3D conformal radiotherapy. All of them were previously treated with surgery and chemotherapy. The brain and upper spinal cord were treated with two lateral 6 MV photon fields. In four patients, the cribriform plate was irradiated by the additional field. For primary tumour bed we applied two or three photon beams. Spinal cord was irradiated either with 18-20 MeV electron fields or with a mixed beam. Results: With a median follow-up of 48 months, 32/95 patients suffered a multifocal (21) or isolated (11) recurrence. We evaluated every primary site of failure. In all patients, the recurrence appeared within the isodose level of 95-100%. Conclusions: Patterns of failure in medulloblastoma patients treated with 3D conformal radiotherapy indicated that the relapse was mainly associated with poor response to pre-irradiation chemotherapy. We believe that 3D conformal radiotherapy allows avoiding failures, related to radiotherapy uncertainties

Excimer laser beam profile recording based on electrochemical etched polycarbonate

International Nuclear Information System (INIS)

Parvin, P.; Jaleh, B.; Zangeneh, H.R.; Zamanipour, Z.; Davoud-Abadi, Gh.R.

2008-01-01

There is no polymeric detector used to register the beam profile of UV lasers. Here, a method is proposed for the measurement of intensive UV beam pattern of the excimer lasers based on the photoablated polycarbonate detector after coherent UV exposure and the subsequent electrochemical etching. UV laser induced defects in the form of self-microstructuring on polycarbonate are developed to replicate the spatial intensity distribution as a beam profiler

Excimer laser beam profile recording based on electrochemical etched polycarbonate

Energy Technology Data Exchange (ETDEWEB)

Parvin, P. [Physics Department, Amirkabir University of Technology, P.O. Box 15875-4413, Hafez Ave, Tehran (Iran, Islamic Republic of); Laser Research Center, AEOI, P.O. Box 1165-8486, Tehran (Iran, Islamic Republic of)], E-mail: parvin@aut.ac.ir; Jaleh, B. [Physics Department, Bu-Ali Sina University, Postal Code 65174, Hamedan (Iran, Islamic Republic of); Zangeneh, H.R. [Physics Department, Amirkabir University of Technology, P.O. Box 15875-4413, Hafez Ave, Tehran (Iran, Islamic Republic of); Zamanipour, Z. [Laser Research Center, AEOI, P.O. Box 1165-8486, Tehran (Iran, Islamic Republic of); Davoud-Abadi, Gh.R. [Physics Department, Amirkabir University of Technology, P.O. Box 15875-4413, Hafez Ave, Tehran (Iran, Islamic Republic of)

2008-08-15

There is no polymeric detector used to register the beam profile of UV lasers. Here, a method is proposed for the measurement of intensive UV beam pattern of the excimer lasers based on the photoablated polycarbonate detector after coherent UV exposure and the subsequent electrochemical etching. UV laser induced defects in the form of self-microstructuring on polycarbonate are developed to replicate the spatial intensity distribution as a beam profiler.

Acoustic non-diffracting Airy beam

International Nuclear Information System (INIS)

Lin, Zhou; Guo, Xiasheng; Tu, Juan; Ma, Qingyu; Wu, Junru; Zhang, Dong

2015-01-01

The acoustic non-diffracting Airy beam as its optical counterpart has unique features of self-bending and self-healing. The complexity of most current designs handicaps its applications. A simple design of an acoustic source capable of generating multi-frequency and broad-band acoustic Airy beam has been theoretically demonstrated by numerical simulations. In the design, a piston transducer is corrugated to induce spatial phase variation for transducing the Airy function. The piston's surface is grooved in a pattern that the width of each groove corresponds to the half wavelength of Airy function. The resulted frequency characteristics and its dependence on the size of the piston source are also discussed. This simple design may promote the wide applications of acoustic Airy beam particularly in the field of medical ultrasound

Proposed dedicated high pressure beam lines at CHESS

International Nuclear Information System (INIS)

Ruoff, A.L.; Vohra, Y.K.; Bassett, W.A.; Batterman, B.W.; Bilderback, D.H.

1988-01-01

An instrumentation proposal for dedicated high pressure beam lines at CHESS is described. It is the purpose of this proposed program to provide researchers in high pressure science with beam lines for X-ray diffraction studies in the megabar regime. This will involve radiation from a bending magnet as well as from a wiggler. Examples of the high pressure results up to 2.16 Mbar are shown. Diffraction patterns from bending magnet and wiggler beams are shown and compared. The need for this facility by the high pressure community is discussed. (orig.)

Multi-Aperture Digital Coherent Combining for Free-Space Optical Communication Receivers

Science.gov (United States)

2016-04-21

emulated by a cascade of fiber beam splitters . Fig. 4(a) depicts the transmitter, which consisted of two cascaded Mach- Zehnder modulators (MZMs) that...Sons, Inc., Hoboken, New Jersey, 2006). 5. D. O. Caplan, "Laser communication transmitter and receiver design ," J. Opt. Fiber. Commun. 4(4-5), 225...and A. E. Willner, eds. (Elsevier, 2013). 7. S. B. Alexander, Optical Communication Receiver Design (SPIE, 1997). 8. D. M. Boroson, "A survey of

Simultaneous Transmit and Receive Performance of an 8-channel Digital Phased Array

Science.gov (United States)

2017-01-16

hardware. An 8-channel ALSTAR array prototype was constructed and demonstrated to achieve 125.5 dB effective isotropic isolation between broadside...transmit and receive beams over a 100 MHz instantaneous band centered at 2.45 GHz. I. INTRODUCTION A phased array capable of Simultaneous Transmit and...Receive (STAR) could provide significant benefits for many applications including communications, radar, spectral sens- ing, and multifunctional systems

Low-Profile, Dual-Wavelength, Dual-Polarized Antenna

Science.gov (United States)

Carswell, James R.

2010-01-01

A single-aperture, low-profile antenna design has been developed that supports dual-polarization and simultaneous operation at two wavelengths. It realizes multiple beams in the elevation plane, and supports radiometric, radar, and conical scanning applications. This antenna consists of multiple azimuth sticks, with each stick being a multilayer, hybrid design. Each stick forms the h-plane pattern of the C and Ku-band vertically and horizontally polarized antenna beams. By combining several azimuth sticks together, the elevation beam is formed. With a separate transceiver for each stick, the transmit phase and amplitude of each stick can be controlled to synthesize a beam at a specific incidence angle and to realize a particular side-lobe pattern. By changing the transmit phase distribution through the transceivers, the transmit antenna beam can be steered to different incidence angles. By controlling the amplitude distribution, different side lobe patterns and efficiencies can be realized. The receive beams are formed using digital beam synthesis techniques, resulting in very little loss in the receive path, thus enabling a very-low loss receive antenna to support passive measurements.

Compact beam splitters with deep gratings for miniature photonic integrated circuits: design and implementation aspects.

Science.gov (United States)

Chen, Chin-Hui; Klamkin, Jonathan; Nicholes, Steven C; Johansson, Leif A; Bowers, John E; Coldren, Larry A

2009-09-01

We present an extensive study of an ultracompact grating-based beam splitter suitable for photonic integrated circuits (PICs) that have stringent density requirements. The 10 microm long beam splitter exhibits equal splitting, low insertion loss, and also provides a high extinction ratio in an integrated coherent balanced receiver. We further present the design strategies for avoiding mode distortion in the beam splitter and discuss optimization of the widths of the detectors to improve insertion loss and extinction ratio of the coherent receiver circuit. In our study, we show that the grating-based beam splitter is a competitive technology having low fabrication complexity for ultracompact PICs.

Geometrical and wave optics of paraxial beams.

Science.gov (United States)

Meron, M; Viccaro, P J; Lin, B

1999-06-01

Most calculational techniques used to evaluate beam propagation are geared towards either fully coherent or fully incoherent beams. The intermediate partial-coherence regime, while in principle known for a long time, has received comparably little attention so far. The resulting shortage of adequate calculational techniques is currently being felt in the realm of x-ray optics where, with the advent of third generation synchrotron light sources, partially coherent beams become increasingly common. The purpose of this paper is to present a calculational approach which, utilizing a "variance matrix" representation of paraxial beams, allows for a straightforward evaluation of wave propagation through an optical system. Being capable of dealing with an arbitrary degree of coherence, this approach covers the whole range from wave to ray optics, in a seamless fashion.

Geometrical correction of the e-beam proximity effect for raster scan systems

Science.gov (United States)

Belic, Nikola; Eisenmann, Hans; Hartmann, Hans; Waas, Thomas

1999-06-01

Increasing demands on pattern fidelity and CD accuracy in e- beam lithography require a correction of the e-beam proximity effect. The new needs are mainly coming from OPC at mask level and x-ray lithography. The e-beam proximity limits the achievable resolution and affects neighboring structures causing under- or over-exposion depending on the local pattern densities and process settings. Methods to compensate for this unequilibrated does distribution usually use a dose modulation or multiple passes. In general raster scan systems are not able to apply variable doses in order to compensate for the proximity effect. For system of this kind a geometrical modulation of the original pattern offers a solution for compensation of line edge deviations due to the proximity effect. In this paper a new method for the fast correction of the e-beam proximity effect via geometrical pattern optimization is described. The method consists of two steps. In a first step the pattern dependent dose distribution caused by back scattering is calculated by convolution of the pattern with the long range part of the proximity function. The restriction to the long range part result in a quadratic sped gain in computing time for the transformation. The influence of the short range part coming from forward scattering is not pattern dependent and can therefore be determined separately in a second step. The second calculation yields the dose curve at the border of a written structure. The finite gradient of this curve leads to an edge displacement depending on the amount of underground dosage at the observed position which was previously determined in the pattern dependent step. This unintended edge displacement is corrected by splitting the line into segments and shifting them by multiples of the writers address grid to the opposite direction.

Pattern data handling system for an electron beam exposure system

International Nuclear Information System (INIS)

Berrian, D.W.; Ward, B.W.

1985-01-01

A beam is blanked over a rectangular area by storing beam blanking data in a bit map memory having data words of n bits. An address counter is loaded with the x-coordinate of the location of the rectangle and inhibited (by word counter) from counting after advancing through a number of addresses corresponding to the length of the rectangle. Mask bits whose position determines the y-coordinate of the location of the rectangle and whose number determines the width of the rectangle are loaded into a mask latch having n bit locations each with an output coupled to write enable inputs of the memory corresponding to the n bits of the data words in the memory. As the address counter advances through the number of addresses corresponding to the length of the rectangle, data describing the rectangle is stored in the memory without altering masked parts of previously stored blanking data. (author)

Atom diffraction with a 'natural' metastable atom nozzle beam

International Nuclear Information System (INIS)

Karam, J-C; Wipf, N; Grucker, J; Perales, F; Boustimi, M; Vassilev, G; Bocvarski, V; Mainos, C; Baudon, J; Robert, J

2005-01-01

The resonant metastability-exchange process is used to obtain a metastable atom beam with intrinsic properties close to those of a ground-state atom nozzle beam (small angular aperture, narrow velocity distribution). The estimated effective source diameter (15 μm) is small enough to provide at a distance of 597 mm a transverse coherence radius of about 873 nm for argon, 1236 nm for neon and 1660 nm for helium. It is demonstrated both by experiment and numerical calculations with He*, Ne* and Ar* metastable atoms, that this beam gives rise to diffraction effects on the transmitted angular pattern of a silicon-nitride nano-slit grating (period 100 nm). Observed patterns are in good agreement with previous measurements with He* and Ne* metastable atoms. For argon, a calculation taking into account the angular aperture of the beam (0.35 mrad) and the effect of the van der Waals interaction-the van der Waals constant C 3 1.83 +0.1 -0.15 au being derived from spectroscopic data-leads to a good agreement with experiment

Study on power coupling of annular vortex beam propagating through a two-Cassegrain-telescope optical system in turbulent atmosphere.

Science.gov (United States)

Wu, Huiyun; Sheng, Shen; Huang, Zhisong; Zhao, Siqing; Wang, Hua; Sun, Zhenhai; Xu, Xiegu

2013-02-25

As a new attractive application of the vortex beams, power coupling of annular vortex beam propagating through a two- Cassegrain-telescope optical system in turbulent atmosphere has been investigated. A typical model of annular vortex beam propagating through a two-Cassegrain-telescope optical system is established, the general analytical expression of vortex beams with limited apertures and the analytical formulas for the average intensity distribution at the receiver plane are derived. Under the H-V 5/7 turbulence model, the average intensity distribution at the receiver plane and power coupling efficiency of the optical system are numerically calculated, and the influences of the optical topological charge, the laser wavelength, the propagation path and the receiver apertures on the power coupling efficiency are analyzed. These studies reveal that the average intensity distribution at the receiver plane presents a central dark hollow profile, which is suitable for power coupling by the Cassegrain telescope receiver. In the optical system with optimized parameters, power coupling efficiency can keep in high values with the increase of the propagation distance. Under the atmospheric turbulent conditions, great advantages of vortex beam in power coupling of the two-Cassegrain-telescope optical system are shown in comparison with beam without vortex.

Design of Steel Beam-Column Connections

Directory of Open Access Journals (Sweden)

Bogatinoski Z.

2014-05-01

Full Text Available In this paper a theoretical and experimental research of the steel beam-column connections is presented. Eight types of specimens were being researched, composed of rigid and semi-rigid connections from which 4 connections are with IPE - profile and 4 connections with tube's section for the beam. From the numerical analysis of the researched models, and especially from the experimental research at the Laboratory for Structures in the Faculty of Mechanical Engineering - Skopje, specific conclusions were received that ought to have theoretical and practical usage for researchers in this area of interest.

Proton beam shaped by “particle lens” formed by laser-driven hot electrons

International Nuclear Information System (INIS)

Zhai, S. H.; Shen, B. F.; Wang, W. P.; Zhang, H.; Zhang, L. G.; Huang, S.; Xu, Z. Z.; He, S. K.; Lu, F.; Zhang, F. Q.; Deng, Z. G.; Dong, K. G.; Wang, S. Y.; Zhou, K. N.; Xie, N.; Wang, X. D.; Liu, H. J.; Zhao, Z. Q.; Gu, Y. Q.; Zhang, B. H.

2016-01-01

Two-dimensional tailoring of a proton beam is realized by a “particle lens” in our experiment. A large quantity of electrons, generated by an intense femtosecond laser irradiating a polymer target, produces an electric field strong enough to change the trajectory and distribution of energetic protons flying through the electron area. The experiment shows that a strip pattern of the proton beam appears when hot electrons initially converge inside the plastic plate. Then the shape of the proton beam changes to a “fountain-like” pattern when these hot electrons diffuse after propagating a distance.

Commissioning results of the APS storage ring rf beam position monitors

International Nuclear Information System (INIS)

Kahana, E.; Chung, Y.

1996-01-01

The commissioning of the 360 rf beam position monitors (BPMs) in the Advanced Photon Source (APS) storage ring (SR) is nearing completion. After using the single-turn capability of the BPM electronics in the early ring commissioning phase, resolution measurements versus current and bandwidth were successfully performed. In the standard Sr vacuum chamber geometry, the resolution was measured with beam as 0.16 micromA/√(Hz). For the insertion device vacuum chamber geometry, the resolution was measured to be 0.1 micromA/√(Hz). Since the photon beam stability requirement for the users is only 4.5 microns rms in the vertical direction, investigations of rf BPM offset versus current and bunch pattern have also been initiated. Both single bunch and multibunch beam patterns with varying intensity were used to determine offset stability for both the global and the local orbit feedback applications

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)

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.)

Silicon microfabricated beam expander

Science.gov (United States)

Othman, A.; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A.; Ain, M. F.

2015-03-01

The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed.

Proportional Reasoning and Rule-Governed Behavior with the Balance Beam.

Science.gov (United States)

Maloney, David P.

1983-01-01

Examined relation between college students' (N=108) ability to solve simple ratio tasks (for example, their proportional reasoning patterns) and their rule-governed behavior with the balance beam. Also identified modifications in a set of rules for the balance beam tasks. Results and implications for science instruction are discussed. (JN)

Interference-aware random beam selection for spectrum sharing systems

KAUST Repository

Abdallah, Mohamed M.

2012-09-01

Spectrum sharing systems have been introduced to alleviate the problem of spectrum scarcity by allowing secondary unlicensed networks to share the spectrum with primary licensed networks under acceptable interference levels to the primary users. In this paper, we develop interference-aware random beam selection schemes that provide enhanced throughput for the secondary link under the condition that the interference observed at the primary link is within a predetermined acceptable value. For a secondary transmitter equipped with multiple antennas, our schemes select a random beam, among a set of power- optimized orthogonal random beams, that maximizes the capacity of the secondary link while satisfying the interference constraint at the primary receiver for different levels of feedback information describing the interference level at the primary receiver. For the proposed schemes, we develop a statistical analysis for the signal-to-noise and interference ratio (SINR) statistics as well as the capacity of the secondary link. Finally, we present numerical results that study the effect of system parameters including number of beams and the maximum transmission power on the capacity of the secondary link attained using the proposed schemes. © 2012 IEEE.

Study of kidney damage in paediatric patients with neurogenic bladder and its relationship with the pattern of bladder function and treatment received.

Science.gov (United States)

Rodríguez-Ruiz, M; Somoza, I; Curros-Mata, N

2016-01-01

Kidney failure is the main cause of morbidity and mortality in patients with myelodysplasia. We analysed the presence of renal lesions in these patients using dimercaptosuccinic acid scintigraphy and related their presence with the type of vesical function and the delay in receiving appropriate management. We performed a retrospective study of patients with myelodysplasia treated in our hospital since 2004. We analysed the epidemiological and clinical data and the pattern of bladder function according to urodynamic studies. We classified the patients into 4 urodynamic patterns according to detrusor and sphincter behaviour. We linked this behaviour to renal function in the scintigraphy and the care received since birth. The study included 39 patients with myelodysplasia. The most common bladder pattern was type A (61.5%), with sphincter and detrusor hyperactivity, followed by type D (20.5%), C (7.8%) and B (5.1%). Some 38% of our patients (n=15) had some type of nephropathy. Some 92.9% of the children who were properly treated during the first year of their life had no renal lesions in the scintigraphy. We found some type of nephropathy in 56% of the patients for whom appropriate treatment was delayed for more than a year. The nephropathy was more severe the later the management was started. There is a statistically significant relationship between a delay in treatment and impairment in renal scintigraphy in patients with neurogenic bladders. The early study and treatment of patients is essential for decreasing renal impairment, reducing the need for surgery and improving the continence options. Copyright © 2014 AEU. Publicado por Elsevier España, S.L.U. All rights reserved.

Novel calibration system with sparse wires for CMB polarization receivers

Energy Technology Data Exchange (ETDEWEB)

Tajima, O.; /KEK, Tsukuba /Chicago U., KICP; Nguyen, H.; /Fermilab; Bischoff, C.; /Chicago U., KICP /Harvard-Smithsonian Ctr. Astrophys.; Brizius, A.; Buder, I.; Kusaka, A. /Chicago U., KICP

2011-07-01

B-modes in the cosmic microwave background (CMB) polarization is a smoking gun signature of the inflationary universe. To achieve better sensitivity to this faint signal, CMB polarization experiments aim to maximize the number of detector elements, resulting in a large focal plane receiver. Detector calibration of the polarization response becomes essential. It is extremely useful to be able to calibrate 'simultaneously' all detectors on the large focal plane. We developed a novel calibration system that rotates a large 'sparse' grid of metal wires, in front of and fully covering the field of view of the focal plane receiver. Polarized radiation is created via the reflection of ambient temperature from the wire surface. Since the detector has a finite beam size, the observed signal is smeared according to the beam property. The resulting smeared polarized radiation has a reasonable intensity (a few Kelvin or less) compared to the sky temperature ({approx}10 K observing condition). The system played a successful role for receiver calibration of QUIET, a CMB polarization experiment located in the Atacama desert in Chile. The successful performance revealed that this system is applicable to other experiments based on different technologies, e.g. TES bolometers.

The Stark effect of 1H and 4He+ in the beam foil source

International Nuclear Information System (INIS)

Doobov, M.H.; Hay, H.J.; Sofield, C.J.; Newton, C.S.

1974-01-01

The appearance of Stark patterns obtained with a beam-foil source differed from those characteristically obtained from gas discharge sources. In the former source excitation of the hydrogenic ions occurred in a brief time interval ( 14 s) during the passage of a high velocity unidirectional beam of ions which produces non-statistical population distributions for the Stark perturbed states. The relative intensities of Stark perturbed components of the Hsub(β) hydrogen line and the Fsub(α) ionized helium line have been measured in a beam-foil source. In each case an initial population of states of principal quantum number n = 4 due to radiative decay and Stark mixing, and comparing the resultant patterns with the observed patterns. The inferred population distributions indicate that the states of low orbital angular momentum (L) are preferentially populated, and alignment referred to the beam axis is produced such that states with lower z component of L are preferentially populated. (author)

Beam Dynamics Studies in Recirculating Machines

CERN Document Server

Pellegrini, Dario; Latina, A

The LHeC and the CLIC Drive Beam share not only the high-current beams that make them prone to show instabilities, but also unconventional lattice topologies and operational schemes in which the time sequence of the bunches varies along the machine. In order to asses the feasibility of these projects, realistic simulations taking into account the most worrisome effects and their interplays, are crucial. These include linear and non-linear optics with time dependent elements, incoherent and coherent synchrotron radiation, short and long-range wakefields, beam-beam effect and ion cloud. In order to investigate multi-bunch effects in recirculating machines, a new version of the tracking code PLACET has been developed from scratch. PLACET2, already integrates most of the effects mentioned before and can easily receive additional physics. Its innovative design allows to describe complex lattices and track one or more bunches accordingly to the machine operation, reproducing the bunch train splitting and recombinat...

Intense positron beam and its application to surface science

International Nuclear Information System (INIS)

Ito, Y.; Hirose, M.; Kanazawa, I.; Sueoka, O.; Takamura, S.; Okada, S.

1992-01-01

Intense pulsed slow positron beam has been produced using the 100 MeV electron LINAC of JAERI · Tokai. In order to use the beam for surface studies such as positron diffraction and positron microscopy, it was transferred from the solenoid magnetic field to field free region and then was brightness-enhanced. The beam size was reduced from 10 mmφ (in the magnetic field) to 0.5 mmφ after two stages of re-moderation. Using the intense brightness-enhanced positron beam we have observed for the first time RHEPD (Reflection High-Energy Positron Diffraction) patterns. A design of re-emission positron microscopy is also described. (author)

Trigger and DAQ in the Combined Test Beam

CERN Multimedia

Dobson, M; Padilla, C

2004-01-01

Introduction During the Combined Test Beam the latest prototype of the ATLAS Trigger and DAQ system is being used to support the data taking of all the detectors. Further development of the TDAQ subsystems benefits from the direct experience given by the integration in the beam test. Support of detectors for the Combined Test Beam All ATLAS detectors need their own detector-specific DAQ development. The readout electronics is controlled by a Readout Driver (ROD), custom-built for each detector. The ROD receives data for events that are accepted by the first level trigger. The detector-specific part of the DAQ system needs to control the ROD and to respond to commands of the central DAQ (e.g. to "Start" a run). The ROD module then sends event data to a Readout System (ROS), a PC with special receiver modules/buffers. At this point the data enters the realm of the ATLAS DAQ and High Level Trigger system, constructed from Linux PCs connected with gigabit Ethernet networks. Most ATLAS detectors, representing s...

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)

An experimental comparison of three wire beam electrode based methods for determining corrosion rates and patterns

International Nuclear Information System (INIS)

Tan, Y.-J.

2005-01-01

Laboratory experiments have been carried out to examine the advantages and limitations of three wire beam electrode (WBE) based techniques, including the noise resistance R n -WBE method, the overpotential-galvanic current method, and the galvanic current method, in determining corrosion rates and patterns. These techniques have been applied simultaneously to several selected corrosion systems of different characteristics. It has been found that the R n -WBE method has advantages over other WBE based methods when applying to WBE surfaces under uniform corrosion. However, the R n -WBE method has been found to be unsuitable for low noise level corrosion systems. It has also been found that both R n -WBE and overpotential-galvanic current methods are similarly applicable to WBE surfaces under nonuniform corrosion. However, the galvanic current method has been found to be suitable only for WBE surfaces under highly localised corrosion. Some related issues regarding R n calculation such as trend removal and its effects on corrosion mapping have also been discussed

A possible interpretation of the zebra pattern in solar radiation

International Nuclear Information System (INIS)

Fomichev, V. V.; Fainshtein, S. M.; Chernov, G. P.

2009-01-01

The nature of the zebra pattern in continual type-IV solar radio bursts is discussed. It is shown that, when a weakly relativistic monoenergetic proton beam propagates in a highly nonisothermal plasma, the energy of the slow beam mode can be negative and explosive instability can develop due to the interaction of the slow and fast beam modes with ion sound. Due to weak spatial dispersion, ion sound generation is accompanied by cascade merging, which leads to stabilization of explosive instability. The zebra pattern forms due to the scattering of fast protons by ion sound harmonics. The efficiency of the new mechanism is compared with that of previously discussed mechanisms.

Polystyrene negative resist for high-resolution electron beam lithography

Directory of Open Access Journals (Sweden)

Ma Siqi

2011-01-01

Full Text Available Abstract We studied the exposure behavior of low molecular weight polystyrene as a negative tone electron beam lithography (EBL resist, with the goal of finding the ultimate achievable resolution. It demonstrated fairly well-defined patterning of a 20-nm period line array and a 15-nm period dot array, which are the densest patterns ever achieved using organic EBL resists. Such dense patterns can be achieved both at 20 and 5 keV beam energies using different developers. In addition to its ultra-high resolution capability, polystyrene is a simple and low-cost resist with easy process control and practically unlimited shelf life. It is also considerably more resistant to dry etching than PMMA. With a low sensitivity, it would find applications where negative resist is desired and throughput is not a major concern.

Effect of electron beam irradiation on the nutritional ingredient of Sciaenops ocellatus meat

International Nuclear Information System (INIS)

Zhang Chunfang; Yang Wenge; Xu Dalun; Shi Huidong

2011-01-01

The influences of electron beam irradiation and package pattern (vacuum or ordinary) on the nutritional ingredient of Sciaenops ocellatus meat were investigated. The results were summarized as follows: (1) Electron-beam irradiation dose had notable effect on the moisture content, but no significant impact on the content of ash, protein, lipid and total carbohydrate. Teh package pattern had no significant effect on the common nutrional composition of Sciaenops ocellatus meat. (2) Either package pattern or irradiation dose showed little influence on the total amino acids, delicious amino acid, EAA/TAA and EAA/NEAA of Sciaenops ocellatus meat. The first limiting amino acid of Sciaenops ocellatus meat changed from Met plus Cys to Val in virtue of electron beam irradiation. (3) Both irradiation dose and package pattern showed no difference to the total fatty acid content. But the irradiation dose had notable effect on the relative content of unsaturated fatty acid, polyunsaturated fatty acid and DHA. The vacuum-packaged group had less DHA loss than the ordinary-packaged group with the same absorbed dose, and low dose groups had less DHA loss than the high groups. As conclusion, combining with the bactericidal effect of electron beam irradiation to Sciaenops ocellatus meat, the recommended dose has been proposed to be 3-5 kGy. (authors)

Fabrication of Multi-Harmonic Buncher for Pulsed Proton Beam Generation

Energy Technology Data Exchange (ETDEWEB)

Kim, H. S.; Kwon, H. J.; Cho, Y. S. [Korea Multipurpose Accelerator Complex, Gyeongju (Korea, Republic of)

2015-05-15

Fast neutrons with a broad spectrum can be generated by irradiating the proton beams on target materials. To measure the neutron energy by time of flight (TOF) method, the short pulse width of the proton beam is preferred because the neutron energy uncertainty is proportional to the pulse width. In addition, the pulse repetition rate should be low enough to extend the lower limit of the available neutron energy. Pulsed proton beam generation system is designed based on an electrostatic deflector and slit system as shown in Fig. 1. In a simple deflector with slit system, most of the proton beam is blocked by slit, especially when the beam pulse width is short. The ideal field pattern inside the buncher cavity is saw-tooth wave. To make the field pattern similar to the saw-tooth waveform, we adopted a multi-harmonic buncher (MHB). The design for the multi-harmonic buncher including 3D electromagnetic calculation has been performed. Based on the design, a multi-harmonic buncher cavity was fabricated. It consists of two resonators, two drift tubes and a vacuum chamber. The resonator is a quarter-wave coaxial resonator type. The drift tube is connected to the resonator by using a coaxial vacuum feedthrough. Design summary and detailed fabrication method of the multi-harmonic buncher is presented in this paper. A multi-harmonic buncher for a proton beam chopper system to generate a short pulse neutron beam was designed, fabricated and assembled.

The Experimental Verification of Gaussian Beam Coupling for ECH Transmission Line at 400 GHz

Directory of Open Access Journals (Sweden)

Choe Mun Seok

2017-01-01

Full Text Available We design a quasi-optical transmission line system for a 400 GHz gyrotron beam. The 400GHz Gaussian beam is injected to a corrugated waveguide bounced from a quasi-optical mirror. From detailed 2D field patterns of the output beam emitted from the corrugated waveguide, we analyze the mode contents and the source of non-ideal beam expansion

Review on structured optical field generated from array beams

Science.gov (United States)

Hou, Tianyue; Zhou, Pu; Ma, Yanxing; Zhi, Dong

2018-03-01

Structured optical field (SOF), which includes vortex beams, non-diffraction beams, cylindrical vector beams and so on, has been under intensive investigation theoretically and experimentally in recent years. Generally, current research focus on the extraordinary properties (non-diffraction propagation, helical wavefront, rotation of electrical field, et al), which can be widely applied in micro-particle manipulation, super-resolution imaging, free-space communication and so on. There are mainly two technical routes, that is, inner-cavity and outer-cavity (spatial light modulators, diffractive phase holograms, q-plates). To date, most of the SOFs generated from both technical routes involves with single monolithic beam. As a novel technical route, SOF based on array beams has the advantage in more flexible freedom degree and power scaling potential. In this paper, research achievements in SOF generation based on array beams are arranged and discussed in detail. Moreover, experiment of generating exotic beam by array beams is introduced, which illustrates that SOF generated from array beams is theoretically valid and experimentally feasible. SOF generated from array beams is also beneficial for capacity increasing and data receiving for free-space optical communication systems at long distance.

Antipsychotic Polypharmacy in a Treatment-Refractory Schizophrenia Population Receiving Adjunctive Treatment With Electroconvulsive Therapy

DEFF Research Database (Denmark)

Kristensen, Diana; Hageman, Ida; Bauer, Jeanett

2013-01-01

Antipsychotic polypharmacy (APP) is frequent, but its pattern is unknown in treatment-refractory schizophrenia-spectrum patients receiving electroconvulsive therapy (ECT).......Antipsychotic polypharmacy (APP) is frequent, but its pattern is unknown in treatment-refractory schizophrenia-spectrum patients receiving electroconvulsive therapy (ECT)....

The SPS Beam quality monitor, from design to operation

CERN Document Server

Papotti, G; Follin, F; Shaposhnikova, E

2011-01-01

The SPS Beam Quality Monitor is a system that monitors longitudinal beam parameters on a cycle-by-cycle basis and prevents extraction to the LHC in case the specifications are not met. This avoids losses, unnecessary stress of machine protection components and luminosity degradation, additionally helping efficiency during the filling process. The system has been operational since the 2009 LHC run, checking the beam pattern, its correct position with respect to the LHC references, individual bunch lengths and stability. In this paper the algorithms used, the hardware implementation and the operational aspects are presented.

Pattern generation using axicon lens beam shaping in two-photon polymerisation

International Nuclear Information System (INIS)

Bhuian, B.; Winfield, R.J.; O'Brien, S.; Crean, G.M.

2007-01-01

The fabrication of three-dimensional microstructures by two-photon polymerisation has been widely reported as a viable route to the development of photonic crystals, rotors, bridges and other complex artefacts requiring nanoscale resolution. Conventionally, single point serial writing is used to write the structures but recently multipoint beam delivery using beam division optics has been reported as a method of introducing parallel processing. In this paper we present an alternative and novel approach using an axicon lens to give profiled beam delivery. This enables complete three-dimensional annular structure fabrication without the use of scanning stages. In addition, the concept of axicon delivery is developed further to investigate three-dimensional structure as a function of axicon geometry. A Ti:sapphire laser, with wavelength 795 nm, 80 MHz repetition rate, 100 fs pulse duration and an average power of 700 mW, was used to initiate two-photon polymerisation. The axicon was used, in combination with a 100x microscope objective, to form representative three-dimensional structures based on the annular cell with varying diameter. The structures were written in a Zr-loaded resin prepared on a glass substrate using dip coating deposition of a Zr/PMMA hybrid prepared by the sol-gel method. Annuli with diameters up to 50 μm were characterised in terms of topography and surface roughness using SEM and Zygo interferometer. The writing technique was also extended to fabrication of stacked structures

The beam based alignment technique for the measurements of beam position monitors offsets and beam offsets from quadrupoles in the Pohang Light Source

International Nuclear Information System (INIS)

Kim, K.H.; Huang, J.Y.; Ko, I.S.

1999-01-01

The beam based alignment (BBA) technique is applied to the 2-GeV storage ring of the Pohang Light Source to measure the offsets of beam position monitors. This measurement is particularly necessary for beam position monitors (BPMs) plugged into a long (∼10 m) aluminum chamber, since the mechanical deformation of the vacuum chamber is experienced after repeated heating for the outgassing process, and the BPM positions are changed accordingly. A part of the excitation current of each quadrupole magnet is shunted through an electronic shunt circuit. Then, the closed orbit receives a perturbation due to the current reduction. Using two quadrupole magnets, we can measure the offset of each BPM. Also, the BBA technique is applied to measure the beam offsets from the center of quadrupole magnets, and gives information to the survey team about which quadrupole magnets should be aligned mostly. In this process, we introduce the merit function to reduce various errors such as BPM characteristic changes and the lattice imperfection. By minimizing the merit function, we can get the beam offset as the maximized expectation value. This paper presents the BBA technique used and experimental results taken from the 2-GeV Pohang Light Source (PLS) storage ring. When the BPM offset is measured, it is observed that a 3% of the shunt current is suitable. (author)

Defining the crack pattern of RC beams through the golden section

International Nuclear Information System (INIS)

Fantilli, A P; Chiaia, B; Cennamo, C

2011-01-01

Both in architecture and arts, the golden section has been exclusively taken into consideration for its geometrical properties. Specifically, among all the proportions, the golden section can inspire beauty. Indeed, it has driven the construction of buildings for centuries. Nevertheless, as discussed for the first time in the present paper, static equilibrium of structures calls the golden section into play. This is the case of reinforced concrete beam in four point bending, whose average crack spacing in the constant moment zone increases of a factor equal to the irrational number 1.61803 when the geometrical dimensions of the beam are doubled. In other words, it can be argued that the centrality of golden section in the art of construction has profound physical meanings, as it can bring together the aesthetic of nature and architecture, and the equilibrium of stress flow in solid bodies.

Defining the crack pattern of RC beams through the golden section

Energy Technology Data Exchange (ETDEWEB)

Fantilli, A P; Chiaia, B [Department of Structural and Geotechnical Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino 10129 (Italy); Cennamo, C, E-mail: alessandro.fantilli@polito.it [Department of ' Cultura del Progetto' , Universita di Napoli SUN, via San Lorenzo, Aversa 81031 (Italy)

2011-07-19

Both in architecture and arts, the golden section has been exclusively taken into consideration for its geometrical properties. Specifically, among all the proportions, the golden section can inspire beauty. Indeed, it has driven the construction of buildings for centuries. Nevertheless, as discussed for the first time in the present paper, static equilibrium of structures calls the golden section into play. This is the case of reinforced concrete beam in four point bending, whose average crack spacing in the constant moment zone increases of a factor equal to the irrational number 1.61803 when the geometrical dimensions of the beam are doubled. In other words, it can be argued that the centrality of golden section in the art of construction has profound physical meanings, as it can bring together the aesthetic of nature and architecture, and the equilibrium of stress flow in solid bodies.

Dose calculations algorithm for narrow heavy charged-particle beams

Energy Technology Data Exchange (ETDEWEB)

Barna, E A; Kappas, C [Department of Medical Physics, School of Medicine, University of Patras (Greece); Scarlat, F [National Institute for Laser and Plasma Physics, Bucharest (Romania)

1999-12-31

The dose distributional advantages of the heavy charged-particles can be fully exploited by using very efficient and accurate dose calculation algorithms, which can generate optimal three-dimensional scanning patterns. An inverse therapy planning algorithm for dynamically scanned, narrow heavy charged-particle beams is presented in this paper. The irradiation `start point` is defined at the distal end of the target volume, right-down, in a beam`s eye view. The peak-dose of the first elementary beam is set to be equal to the prescribed dose in the target volume, and is defined as the reference dose. The weighting factor of any Bragg-peak is determined by the residual dose at the point of irradiation, calculated as the difference between the reference dose and the cumulative dose delivered at that point of irradiation by all the previous Bragg-peaks. The final pattern consists of the weighted Bragg-peaks irradiation density. Dose distributions were computed using two different scanning steps equal to 0.5 mm, and 1 mm respectively. Very accurate and precise localized dose distributions, conform to the target volume, were obtained. (authors) 6 refs., 3 figs.

A BUNCH TO BUCKET PHASE DETECTOR USING DIGITAL RECEIVER TECHNOLOGY

International Nuclear Information System (INIS)

DELONG, J.; BRENNAN, J.M.; HAYES, T.; LE, T.N.; SMITH, K.

2003-01-01

Transferring high-speed digital signals to a Digital Signal Processor is limited by the IO bandwidth of the DSP. A digital receiver circuit is used to translate high frequency W signals to base-band. The translated output frequency is close to DC and the data rate can be reduced, by decimation, before transfer to the DSP. By translating both the longitudinal beam (bunch) and RF cavity pick-ups (bucket) to DC, a DSP can be used to measure their relative phase angle. The result can be used as an error signal in a beam control servo loop and any phase differences can be compensated

Dynamic spatial structure of spontaneous beams in photorefractive bismuth sillicon oxide

DEFF Research Database (Denmark)

Buchhave, Preben; Lyuksyutov, S.; Vasnetsov, M.

1996-01-01

We report the domain structure of spontaneously occurring beams (subharmonics) in photorefractive bismuth silicon oxide with an applied electric field from 1 to 6 kV/cm and a running grating. The subharmonic beams are generated in a pattern of domains that evolve dynamically as they move through ...

Epitaxial Ni films, e-beam nano-patterning and BMR

Science.gov (United States)

Lukaszew, R. Alejandra; Zhang, Zhengdong; Pearson, Dave; Zambano, Antonio

2004-05-01

We have attempted to clarify possible domain-wall processes present in the recently reported large ballistic magnetoresistance effects in nano-contacts. To that effect we have used e-beam lithography applied to epitaxial Ni films to fabricate nano-bridges in more controlled geometry than electrochemical deposition. Our preliminary results indicate that magnetic domains do play a role in the magneto-resistance of these nano-bridges but the order of magnitude of the observed effect is considerably smaller than the reported observations in electrochemically prepared nano-contacts.

Epitaxial Ni films, e-beam nano-patterning and BMR

International Nuclear Information System (INIS)

Lukaszew, R.A.; Zhang Zhengdong; Pearson, Dave; Zambano, Antonio

2004-01-01

We have attempted to clarify possible domain-wall processes present in the recently reported large ballistic magnetoresistance effects in nano-contacts. To that effect we have used e-beam lithography applied to epitaxial Ni films to fabricate nano-bridges in more controlled geometry than electrochemical deposition. Our preliminary results indicate that magnetic domains do play a role in the magneto-resistance of these nano-bridges but the order of magnitude of the observed effect is considerably smaller than the reported observations in electrochemically prepared nano-contacts

Preparation of highly oriented poly-diacetylene LB-films with ion beam irradiation

International Nuclear Information System (INIS)

Hosoi, F.; Aoki, Y.; Hagiwara, M.; Omichi, H.

1992-01-01

Langmuir-Blodgett (LB) films such as 10,12-heptacosa-diynoic acid, 10,12-pentacosa-diynoic acid, 10,12-tricosa-diynoic acid were irradiated with ion beam, electron beam and UV-light, and the effect of irradiation on morphology of the polymerized film was studied. A sharp and intense X-ray diffraction pattern with higher order peaks which was not observed in the original films was obtained by Fe + beam irradiation. The interlayer spacing of diacetylene molecules calculated from the X-ray diffraction experiment was much longer than that theoretically anticipated. Similar results were observed when LB-films were treated with Ar + beam of 1keV for a short time although there was little observation of polymerization. In contrast, the diffraction pattern of the films polymerized with UV-light was broad and weak, and higher order peaks disappeared with the increase in irradiation dose. (author)

Silicon microfabricated beam expander

International Nuclear Information System (INIS)

Othman, A.; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A.; Ain, M. F.

2015-01-01

The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed

Silicon microfabricated beam expander

Energy Technology Data Exchange (ETDEWEB)

Othman, A., E-mail: aliman@ppinang.uitm.edu.my; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A. [Faculty of Electrical Engineering, Universiti Teknologi MARA Malaysia, 40450, Shah Alam, Selangor (Malaysia); Ain, M. F. [School of Electrical and Electronic Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300,Nibong Tebal, Pulau Pinang (Malaysia)

2015-03-30

The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed.

Variable-spot ion beam figuring

International Nuclear Information System (INIS)

Wu, Lixiang; Qiu, Keqiang; Fu, Shaojun

2016-01-01

This paper introduces a new scheme of ion beam figuring (IBF), or rather variable-spot IBF, which is conducted at a constant scanning velocity with variable-spot ion beam collimated by a variable diaphragm. It aims at improving the reachability and adaptation of the figuring process within the limits of machine dynamics by varying the ion beam spot size instead of the scanning velocity. In contrast to the dwell time algorithm in the conventional IBF, the variable-spot IBF adopts a new algorithm, which consists of the scan path programming and the trajectory optimization using pattern search. In this algorithm, instead of the dwell time, a new concept, integral etching time, is proposed to interpret the process of variable-spot IBF. We conducted simulations to verify its feasibility and practicality. The simulation results indicate the variable-spot IBF is a promising alternative to the conventional approach.

Design of a ring resonator-based optical beam forming network for phased array receive antennas

NARCIS (Netherlands)

van 't Klooster, J.W.J.R.; Roeloffzen, C.G.H.; Meijerink, Arjan; Zhuang, L.; Marpaung, D.A.I.; van Etten, Wim; Heideman, Rene; Leinse, Arne; Schippers, H.; Verpoorte, J.; Wintels, M.

2008-01-01

A novel squint-free ring resonator-based optical beam forming network (OBFN) for phased array antennas (PAA) is proposed. It is intended to provide broadband connectivity to airborne platforms via geostationary satellites. In this paper, we present the design of the OBFN and its control system. Our

Using geometric algebra to understand pattern rotations in multiple mirror optical systems

International Nuclear Information System (INIS)

Hanlon, J.; Ziock, H.

1997-01-01

Geometric Algebra (GA) is a new formulation of Clifford Algebra that includes vector analysis without notation changes. Most applications of Ga have been in theoretical physics, but GA is also a very good analysis tool for engineering. As an example, the authors use GA to study pattern rotation in optical systems with multiple mirror reflections. The common ways to analyze pattern rotations are to use rotation matrices or optical ray trace codes, but these are often inconvenient. The authors use GA to develop a simple expression for pattern rotation that is useful for designing or tolerancing pattern rotations in a multiple mirror optical system by inspection. Pattern rotation is used in many optical engineering systems, but it is not normally covered in optical system engineering texts. Pattern rotation is important in optical systems such as: (1) the 192 beam National ignition Facility (NIF), which uses square laser beams in close packed arrays to cut costs; (2) visual optical systems, which use pattern rotation to present the image to the observer in the appropriate orientation, and (3) the UR90 unstable ring resonator, which uses pattern rotation to fill a rectangular laser gain region and provide a filled-in laser output beam

Accurate acoustic and elastic beam migration without slant stack for complex topography

International Nuclear Information System (INIS)

Huang, Jianping; Yuan, Maolin; Li, Zhenchun; Liao, Wenyuan; Yue, Yubo

2015-01-01

Recent trends in seismic exploration have led to the collection of more surveys, often with multi-component recording, in onshore settings where both topography and subsurface targets are complex, leading to challenges for processing methods. Gaussian beam migration (GBM) is an alternative to single-arrival Kirchhoff migration, although there are some issues resulting in unsatisfactory GBM images. For example, static correction will give rise to the distortion of wavefields when near-surface elevation and velocity vary rapidly. Moreover, Green’s function compensated for phase changes from the beam center to receivers is inaccurate when receivers are not placed within some neighborhood of the beam center, that is, GBM is slightly inflexible for irregular acquisition system and complex topography. As a result, the differences of both the near-surface velocity and the surface slope from the beam center to the receivers and the poor spatial sampling of the land data lead to inaccuracy and aliasing of the slant stack, respectively. In order to improve the flexibility and accuracy of GBM, we propose accurate acoustic, PP and polarity-corrected PS beam migration without slant stack for complex topography. The applications of this method to one-component synthetic data from a 2D Canadian Foothills model and a Zhongyuan oilfield fault model, one-component field data and an unseparated multi-component synthetic data demonstrate that the method is effective for structural and relatively amplitude-preserved imaging, but significantly more time-consuming. (paper)

Complementary Speckle Patterns: Deterministic Interchange of Intrinsic Vortices and Maxima through Scattering Media.

Science.gov (United States)

Gateau, Jérôme; Rigneault, Hervé; Guillon, Marc

2017-01-27

Intensity maxima and zeros of speckle patterns obtained behind a diffuser are experimentally interchanged by applying a spiral phase delay of charge ±1 to the impinging coherent beam. This transform arises from the expectation that tightly focused beams, which have a planar wave front around the focus, are so changed into vortex beams and vice versa. The statistics of extrema locations and the intensity distribution of the so-generated "complementary" patterns are characterized by numerical simulations. It is demonstrated experimentally that the incoherent superposition of the three "complementary speckle patterns" yield a synthetic speckle grain size enlarged by a factor of sqrt[3]. A cyclic permutation of optical vortices and intensity maxima is unexpectedly observed and discussed.

Investigation of the depth profile of ion beam induced nanopatterns on Si with simultaneous metal incorporation

Energy Technology Data Exchange (ETDEWEB)

Khanbabaee, Behnam; Arezki, Bahia; Biermanns, Andreas; Pietsch, Ullrich [Festkoerperphysik, Universitaet Siegen, Siegen (Germany); Cornejo, Marina; Frost, Frank [Leibniz-Institut fuer Oberflaechenmodifizierung (IOM), Leipzig (Germany)

2011-07-01

Ion beam sputtering of semiconductor surfaces can modify the surface and produce a diversity of surface topographies such as periodic ripples or dot structures depended on sputtering parameters. Well ordered nanostructured surfaces have widely technological applications. Recent experiments have shown that the incorporation of metallic impurity atoms during the sputtering process plays a crucial role in pattern formation on the surfaces. These findings offer a new degree of freedom to control pattern formation. In this contribution we report on surface patterning due to Kr ion beam erosion on silicon surfaces with simultaneous Fe and Cr incorporation. We used X-ray reflectivity (XRR) to determine the depth profiles of metal ions as function of ion beam divergence angles and the mean incidence angle of the ions with respect to the surface normal. Depth profiles are correlated with degree of pattern formation determined by AFM. We show that the mean penetration depth and concentration of metal ions depends on the divergence angle of Kr beam provided by Kaufman source which supports the assumption that metal ions are created due to parasitic interaction of the Kr beam with the steel plate lining. The evaluated depth profile by XRR is in good agreement with SIMS and RBS results.

Adaptive Forming of the Beam Pattern of Microstrip Antenna with the Use of an Artificial Neural Network

Directory of Open Access Journals (Sweden)

Janusz Dudczyk

2012-01-01

Full Text Available Microstrip antenna has been recently one of the most innovative fields of antenna techniques. The main advantage of such an antenna is the simplicity of its production, little weight, a narrow profile, and easiness of integration of the radiating elements with the net of generators power systems. As a result of using arrays consisting of microstrip antennas; it is possible to decrease the size and weight and also to reduce the costs of components production as well as whole application systems. This paper presents possibilities of using artificial neural networks (ANNs in the process of forming a beam from radiating complex microstrip antenna. Algorithms which base on artificial neural networks use high parallelism of actions which results in considerable acceleration of the process of forming the antenna pattern. The appropriate selection of learning constants makes it possible to get theoretically a solution which will be close to the real time. This paper presents the training neural network algorithm with the selection of optimal network structure. The analysis above was made in case of following the emission source, setting to zero the pattern of direction of expecting interference, and following emission source compared with two constant interferences. Computer simulation was made in MATLAB environment on the basis of Flex Tool, a programme which creates artificial neural networks.

Optimization of a slab heating pattern for minimum energy consumption in a walking-beam type reheating furnace

International Nuclear Information System (INIS)

Jang, Jiin-Yuh; Huang, Jun-Bo

2015-01-01

A two-dimensional mathematical heat transfer model for the prediction of the temperature history of steel slabs was performed in order to obtain the optimal heating pattern of these slabs with minimum energy consumption in a walking-beam type reheating furnace. An algorithm developed with a simplified conjugated-gradient method combined with a shooting method, was used as an optimizer to design the furnace temperature distribution, including the preheating zone, heating zone and soaking zone temperatures. Comparison with the in-situ experimental data indicated that the present heat transfer model works well for the prediction of the thermal behavior of a slab in the reheating furnace. The effect of the furnace temperature distribution on the design requirements, such as energy required for heating a slab, slab temperature uniformity at the furnace exit and slab discharging temperature, were investigated. The parametric study results indicated that energy consumption significantly decreases with reductions in the preheating zone temperature. The optimal design also resulted in lower energy consumption for heating a slab as compared to the original operational conditions in the steel plant. - Highlights: • The heating process of steel slabs in a reheating furnace is numerically simulated. • An algorithm is developed to search for the optimal heating pattern of a slab. • Energy consumption decreases with reductions in the preheating zone temperature

Designing Light Beam Transmittance Measuring Tool Using a Laser Pointer

Science.gov (United States)

Nuroso, H.; Kurniawan, W.; Marwoto, P.

2016-08-01

A simple instrument used for measuring light beam transmittance percentage made of window film has been developed. The instrument uses a laser pointer of 405 nm and 650 nm ±10% as a light source. Its accuracy approaches 80%. Transmittance data was found by comparing the light beam before and after passing the window film. The light intensity measuring unit was deleted by splitting the light source into two beams through a beam splitter. The light beam was changed into resistance by a NORP12 LDR sensor designed at a circuit of voltage divider rule of Khirchoff's laws. This conversion system will produce light beam intensity received by the sensor to become an equal voltage. This voltage will, then, be presented on the computer screen in the form of a real time graph via a 2.0 USB data transfer.

Measurement of the electron beam mode in earth's foreshock

Science.gov (United States)

Onsager, T. G.; Holzworth, R. H.

1990-01-01

High frequency electric field measurements from the AMPTE IRM plasma wave receiver are used to identify three simultaneously excited electrostatic wave modes in the earth's foreshock region: the electron beam mode, the Langmuir mode, and the ion acoustic mode. A technique is developed which allows the rest frame frequecy and wave number of the electron beam waves to be determined. It is shown that the experimentally determined rest frame frequency and wave number agree well with the most unstable frequency and wave number predicted by linear homogeneous Vlasov theory for a plasma with Maxwellian background electrons and a Lorentzian electron beam. From a comparison of the experimentally determined and theoretical values, approximate limits are put on the electron foreshock beam temperatures. A possible generation mechanism for ion acoustic waves involving mode coupling between the electron beam and Langmuir modes is also discussed.

A DSP-Based Beam Current Monitoring System for Machine Protection Using Adaptive Filtering

International Nuclear Information System (INIS)

J. Musson; H. Dong; R. Flood; C. Hovater; J. Hereford

2001-01-01

The CEBAF accelerator at Jefferson Lab is currently using an analog beam current monitoring (BCM) system for its machine protection system (MPS), which has a loss accuracy of 2 micro-amps. Recent burn-through simulations predict catastrophic beam line component failures below 1 micro-amp of loss, resulting in a blind spot for the MPS. Revised MPS requirements target an ultimate beam loss accuracy of 250 nA. A new beam current monitoring system has been developed which utilizes modern digital receiver technology and digital signal processing concepts. The receiver employs a direct-digital down converter integrated circuit, mated with a Jefferson Lab digital signal processor VME card. Adaptive filtering is used to take advantage of current-dependent burn-through rates. Benefits of such a system include elimination of DC offsets, generic algorithm development, extensive filter options, and interfaces to UNIX-based control systems

First beam test of a combined ramp and squeeze at LHC

CERN Document Server

Wenninger, Jorg; Coello De Portugal - Martinez Vazquez, Jaime Maria; Gorzawski, Arkadiusz; Redaelli, Stefano; Schaumann, Michaela; Solfaroli Camillocci, Matteo; CERN. Geneva. ATS Department

2015-01-01

With increasing maturity of LHC operation it is possible to envisage more complex beam manipulations. At the same time operational efficiency receives increasing attention. So far ramping the beams to their target energy and squeezing the beams to smaller or higher beta are decoupled at the LHC. (De-)squeezing is always performed at the target energy, currently 6.5 TeV. Studies to combine the ramp and squeeze processes have been made for the LHC since 2011, but so far no experimental test with beam had ever performed. This note describes the first machine experiment with beam aiming at validating the combination of ramp and squeeze, the so-called combined ramp and squeeze (CRS).

Beaconless operation for optimal laser beam propagation through turbulent atmosphere

Science.gov (United States)

Khizhnyak, Anatoliy; Markov, Vladimir

2016-09-01

Corruption of the wavefront, beam wondering and power density degradation at the receiving end are the effects typically observed at laser beam propagation through turbulent atmosphere. Compensation of these effects can be achieved if the reciprocal conditions for the propagating wave are satisfied along the propagation range. Practical realization of these conditions requires placing a localized beacon at the receiving end of the range and high-performance adaptive optics system (AOS). The key condition for an effective performance of AOS is a high value of the reciprocal component in the outgoing wave, since only this component is getting compensated after propagating turbulence perturbed path. The nonreciprocal components that is present in the wave directed toward the target is caused by three factors (detailed in this paper) that determine the partial restoration of the structure of the beacon beam. Thus solution of a complex problem of focusing the laser beam propagating through turbulent media can be achieved for the share of the outgoing wave that has a reciprocal component. This paper examines the ways and means that can be used in achieving the stated goal of effective laser power delivery on the distant image-resolved object.

Characterization of the Goubau line for testing beam diagnostic instruments

Science.gov (United States)

Kim, S. Y.; Stulle, F.; Sung, C. K.; Yoo, K. H.; Seok, J.; Moon, K. J.; Choi, C. U.; Chung, Y.; Kim, G.; Woo, H. J.; Kwon, J.; Lee, I. G.; Choi, E. M.; Chung, M.

2017-12-01

One of the main characteristics of the Goubau line is that it supports a low-loss, non-radiated surface wave guided by a dielectric-coated metal wire. The dominant mode of the surface wave along the Goubau line is a TM01 mode, which resembles the pattern of the electromagnetic fields induced in the metallic beam pipe when the charged particle beam passes through it. Therefore, the Goubau line can be used for the preliminary bench test and performance optimization of the beam diagnostic instruments without requiring charged particle beams from the accelerators. In this paper, we discuss the basic properties of the Goubau line for testing beam diagnostic instruments and present the initial test results for button-type beam position monitors (BPMs). The experimental results are consistent with the theoretical estimations, which indicates that Goubau line allows effective testing of beam diagnostic equipment.

Experimental demonstration of spatially coherent beam combining using optical parametric amplification.

Science.gov (United States)

Kurita, Takashi; Sueda, Keiichi; Tsubakimoto, Koji; Miyanaga, Noriaki

2010-07-05

We experimentally demonstrated coherent beam combining using optical parametric amplification with a nonlinear crystal pumped by random-phased multiple-beam array of the second harmonic of a Nd:YAG laser at 10-Hz repetition rate. In the proof-of-principle experiment, the phase jump between two pump beams was precisely controlled by a motorized actuator. For the demonstration of multiple-beam combining a random phase plate was used to create random-phased beamlets as a pump pulse. Far-field patterns of the pump, the signal, and the idler indicated that the spatially coherent signal beams were obtained on both cases. This approach allows scaling of the intensity of optical parametric chirped pulse amplification up to the exa-watt level while maintaining diffraction-limited beam quality.

Laser control of atomic beam motion and applications

International Nuclear Information System (INIS)

Balykin, V.I.; Letokhov, V.S.

1987-01-01

The authors present the results of an experimental investigation of the control of atomic beam motion by the light pressure of laser radiation. Collimation, focusing and reflection of the atomic beam are considered. Collimation of the atomic beam is achieved by the interaction of laser radiation with atoms, when the light pressure force depends only on the atom's velocity. A similar regime of atomic beam interaction with radiation was performed with transversal irradiation of a beam by the axis-symmetrical field. The axis-symmetrical field was formed by laser radiation reflected from the conical mirror surface of a reflecting axicon. The axis of the atomic beam coincided with that of the axicon. The collimation regime was reached under negative detuning of the laser radiation frequency from the atomic transition frequency by a value equal to several homogeneous widths. With positive detuning by the same value the regime of beam decollimation was observed. The density of atoms on the beam axis was changed by 10 3 times, when the collimation regime was replaced by that of decollimation. Focusing of the atomic beam was achieved by light pressure dependent on the atomic coordinate. Focusing was performed within the field configuration formed by divergent laser Gaussian beams propagating in the direction +- X, +- Y of a Cartesian coordinate system. Waists of the laser beams were an equal distance from the atomic beam axis. With an atomic beam propagating along the z axis, expressions for local distance and a formula for the laser lens were obtained. Focusing of the atomic beam was experimentally accomplished, and the image of the atomic beam was received. In this work they also investigated reflection of the atomic beam by laser radiation. The possibility of creating the optics of a neutral atomic beam is shown

A new high-speed X-ray beam chopper

International Nuclear Information System (INIS)

McPherson, A.; Wang, J.; Lee, P. L.; Mills, D. M.

1999-01-01

A new high-speed x-ray beam chopper using laser scanner technology has been developed and tested on the SRI-CAT sector 1 beamline at the Advanced Photon Source (APS) storage ring (1). As illustrated in figure 1, it is compact in size and has two sets of transmission windows: BK-7 glass for visible light transmission and 0.23-mm-thick Be for the transmission of x-rays. The rotor is made of aluminum and has a diameter of 50.8 mm. A 0.5-mm-wide and 2.29-mm-tall slit is cut through the center of the rotor. The circumference of the rotor has a coating of 1-mm-thick Ni, which gives an attenuation of 10 8 at 30 keV. Turning at nearly 80000 RPM, this beam chopper has an opening time window of 2450 ns, corresponding to 67% of the revolution time of the APS storage ring. The primary feature in selecting laser scanner technology to develop into an x-ray beam chopper was the high level of rotational speed control of the rotor that makes up the beam chopper element (2). By using an optical feedback circuit to sample the rotational speed four times each revolution, the jitter in the position of the transmission open time window is only 3 ns at the 3 standard deviation level. The APS storage ring orbital frequency, supplied by the control room, is divided down to provide the appropriate drive frequency for the beam chopper motor controller. By this means, both the storage ring and the beam chopper are operating off the same master clock. After a turn-on time of about 15 to 20 seconds, the rotational precision of the motor results in immediate phase locking to the temporal structure of the APS storage ring. By inserting a Stanford delay generator between the frequency divider and the beam chopper motor controller, the phase between the storage ring temporal structure and the beam chopper rotation can be adjusted to position the transmission time window of the beam chopper on any desired part of the storage ring fill pattern. If an asymmetric fill pattern is used in the APS storage

Radiation dermatitis following electron beam therapy

International Nuclear Information System (INIS)

Price, N.M.

1978-01-01

Ten patients, who had been treated for mycosis fungoides with electron beam radiation ten or more years previously, were examined for signs of radiation dermatitis. Although most patients had had acute radiation dermatitis, only a few manifested signs of mild chronic changes after having received between 1,000 and 2,800 rads

A simulation of temperature influence on echolocation click beams of the Indo-Pacific humpback dolphin (Sousa chinensis).

Science.gov (United States)

Song, Zhongchang; Zhang, Yu; Wang, Xianyan; Wei, Chong

2017-10-01

A finite element method was used to investigate the temperature influence on sound beams of the Indo-Pacific humpback dolphin. The numerical models of a dolphin, which originated from previous computed tomography (CT) scanning and physical measurement results, were used to investigate sound beam patterns of the dolphin in temperatures from 21 °C to 39 °C, in increments of 2 °C. The -3 dB beam widths across the temperatures ranged from 9.3° to 12.6°, and main beam angle ranged from 4.7° to 7.2° for these temperatures. The subsequent simulation suggested that the dolphin's sound beam patterns, side lobes in particular, were influenced by temperature.

Fundamental limits on beam stability at the Advanced Photon Source

International Nuclear Information System (INIS)

Decker, G. A.

1998-01-01

Orbit correction is now routinely performed at the few-micron level in the Advanced Photon Source (APS) storage ring. Three diagnostics are presently in use to measure and control both AC and DC orbit motions: broad-band turn-by-turn rf beam position monitors (BPMs), narrow-band switched heterodyne receivers, and photoemission-style x-ray beam position monitors. Each type of diagnostic has its own set of systematic error effects that place limits on the ultimate pointing stability of x-ray beams supplied to users at the APS. Limiting sources of beam motion at present are magnet power supply noise, girder vibration, and thermal timescale vacuum chamber and girder motion. This paper will investigate the present limitations on orbit correction, and will delve into the upgrades necessary to achieve true sub-micron beam stability

A high resolution, single bunch, beam profile monitor

International Nuclear Information System (INIS)

Norem, J.

1992-01-01

Efficient linear colliders require very small beam spots to produce high luminosities with reasonable input power, which limits the number of electrons which can be accelerated to high energies. The small beams, in turn, require high precision and stability in all accelerator components. Producing, monitoring and maintaining beams of the required quality has been, and will continue to be, difficult. A beam monitoring system which could be used to measure beam profile, size and stability at the final focus of a beamline or collider has been developed and is described here. The system uses nonimaging bremsstrahlung optics. The immediate use for this system would be examining the final focus spot at the SLAC/FFTB. The primary alternatives to this technique are those proposed by P. Chen / J. Buon, which analyses the energy and angular distributions of ion recoils to determine the aspect ratio of the electron bunch, and a method proposed by Shintake, which measures intensity variation of compton backscattered photons as the beam is moved across a pattern of standing waves produced by a laser

An Electronically Controlled 8-Element Switched Beam Planar Array

KAUST Repository

Sharawi, Mohammad S.

2015-02-24

An 8-element planar antenna array with electronically controlled switchable-beam pattern is proposed. The planar antenna array consists of patch elements and operates in the 2.45 GHz ISM band. The array is integrated with a digitally controlled feed network that provides the required phases to generate 8 fixed beams covering most of the upper hemisphere of the array. Unlike typical switchable beam antenna arrays, which operate only in one plane, the proposed design is the first to provide full 3D switchable beams with simple control. Only a 3-bit digital word is required for the generation of the 8 different beams. The integrated array is designed on a 3-layer PCB on a Taconic substrate (RF60A). The total dimensions of the fabricated array are 187.1 × 261.3 × 1.3mm³.

Fabrication of a negative PMMA master mold for soft-lithography by MeV ion beam lithography

Science.gov (United States)

Puttaraksa, Nitipon; Unai, Somrit; Rhodes, Michael W.; Singkarat, Kanda; Whitlow, Harry J.; Singkarat, Somsorn

2012-02-01

In this study, poly(methyl methacrylate) (PMMA) was investigated as a negative resist by irradiation with a high-fluence 2 MeV proton beam. The beam from a 1.7 MV Tandetron accelerator at the Plasma and Beam Physics Research Facility (PBP) of Chiang Mai University is shaped by a pair of computer-controlled L-shaped apertures which are used to expose rectangular pattern elements with 1-1000 μm side length. Repeated exposure of rectangular pattern elements allows a complex pattern to be built up. After subsequent development, the negative PMMA microstructure was used as a master mold for casting poly(dimethylsiloxane) (PDMS) following a standard soft-lithography process. The PDMS chip fabricated by this technique was demonstrated to be a microfluidic device.

Fabrication of a negative PMMA master mold for soft-lithography by MeV ion beam lithography

International Nuclear Information System (INIS)

Puttaraksa, Nitipon; Unai, Somrit; Rhodes, Michael W.; Singkarat, Kanda; Whitlow, Harry J.; Singkarat, Somsorn

2012-01-01

In this study, poly(methyl methacrylate) (PMMA) was investigated as a negative resist by irradiation with a high-fluence 2 MeV proton beam. The beam from a 1.7 MV Tandetron accelerator at the Plasma and Beam Physics Research Facility (PBP) of Chiang Mai University is shaped by a pair of computer-controlled L-shaped apertures which are used to expose rectangular pattern elements with 1–1000 μm side length. Repeated exposure of rectangular pattern elements allows a complex pattern to be built up. After subsequent development, the negative PMMA microstructure was used as a master mold for casting poly(dimethylsiloxane) (PDMS) following a standard soft-lithography process. The PDMS chip fabricated by this technique was demonstrated to be a microfluidic device.

Optimized lens-sparing treatment of retinoblastoma with electron beams

International Nuclear Information System (INIS)

Steenbakkers, Roel J.H.M.; Altschuler, Martin D.; D'Angio, Giulio J.; Goldwein, Joel W.; Kassaee, Alireza

1997-01-01

Purpose: The ideal lens-sparing radiotherapy technique for retinoblastoma calls for 100% dose to the entire retina including the ora serrata and zero dose to the lens. Published techniques, most of which use photons, have not accomplished this ideal treatment. We describe here a technique that approaches this ideal configuration using electron beam therapy. Methods and Materials: Dose-modeling calculations were made using a computer program built around a proprietary algorithm. This program calculates 3D dose distribution for electrons and photons and uses the Cimmino feasibility method for the inverse problem of beam weighting to achieve the prescribed dose. The algorithm has been verified in the ocular region by measurements in a RANDO phantom. To search for an ideal lens-sparing beam setup, a stylized phantom of an 8-month-old infant was generated with built-in inhomogeneities, and a phantom of a 5-year-old child was generated from a patient CT series. Results: Of more than 100 different beam setups tested, two 9 MeV electron beams at gantry angles plus and minus 26 degrees from the optic nerve axis achieved the best distribution. Both fields have a lens block and an isocenter between the globe and origin of the optic nerve. When equal doses are given to both fields, the entire extent of the retina (including ora serrata) received 100%, while the lens received 10% or less. Conclusion: The two-oblique-electron-beam technique here described appears to meet most of the stringent dosimetry needed to treat retinoblastoma. It is suitable for a range of ages, from infancy to early childhood years

Implementation and performance of beam smoothing on 10 beams of the Nova Laser

International Nuclear Information System (INIS)

Pennington, D.M.

1997-01-01

Recent simulations and experiments on Nova indicate that some level of smoothing may be required to suppress filamentation in plasmas on the National Ignition Facility (NIF), resulting in the addition of 1-D smoothing capability to the current baseline design. Control of stimulated Brillouin scattering (SBS) and filamentation is considered essential to the success of laser fusion because they affect the amount and location of laser energy delivered to the x-ray conversion region (hohlraum wall) for indirect drive and to the absorptive region for direct drive, Smoothing by spectral dispersion (SSD)[1], reduces these instabilities by reducing nonuniformities in the focal irradiance when averaged over a finite time interval. We have installed SSD on Nova to produce beam smoothing on all 10 beam lines. A single dispersion grating is located in a position common to all 10 beam lines early in the preamplifier chain. This location limits the 1 ω bandwidth to 2.2 (angstrom) with sufficient dispersion to displace the speckle field of each frequency component at the target plane by one half speckle diameter. Several beam lines were modified to allow orientation of the dispersion on each arm relative to the hohlraum wall. After conversion to the third harmonic the beam passes through a kinoform phase plate (KPP) designed to produce an elliptical spot at best focus. The KPPs produce a focal spot having an elliptical flat-top envelope with a superimposed speckle pattern. Over 93% of the energy is contained in the central 400 km. Calculations indicate a 16% rms. intensity variance will be reached after 330 ps for a single beam

Patterns of Care Among Patients Receiving Radiation Therapy for Bone Metastases at a Large Academic Institution

Energy Technology Data Exchange (ETDEWEB)

Ellsworth, Susannah G. [Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Alcorn, Sara R., E-mail: salcorn2@jhmi.edu [Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Hales, Russell K.; McNutt, Todd R.; DeWeese, Theodore L. [Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Smith, Thomas J. [Department of Medical Oncology and Harry J. Duffey Family Program in Palliative Care, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States)

2014-08-01

Purpose: This study evaluates outcomes and patterns of care among patients receiving radiation therapy (RT) for bone metastases at a high-volume academic institution. Methods and Materials: Records of all patients whose final RT course was for bone metastases from April 2007 to July 2012 were identified from electronic medical records. Chart review yielded demographic and clinical data. Rates of complicated versus uncomplicated bone metastases were not analyzed. Results: We identified 339 patients whose final RT course was for bone metastases. Of these, 52.2% were male; median age was 65 years old. The most common primary was non-small-cell lung cancer (29%). Most patients (83%) were prescribed ≤10 fractions; 8% received single-fraction RT. Most patients (52%) had a documented goals of care (GOC) discussion with their radiation oncologist; hospice referral rates were higher when patients had such discussions (66% with vs 50% without GOC discussion, P=.004). Median life expectancy after RT was 96 days. Median survival after RT was shorter based on inpatient as opposed to outpatient status at the time of consultation (35 vs 136 days, respectively, P<.001). Hospice referrals occurred for 56% of patients, with a median interval between completion of RT and hospice referral of 29 days and a median hospice stay of 22 days. Conclusions: These data document excellent adherence to American Society for Radiation Oncolology Choosing Wisely recommendation to avoid routinely using >10 fractions of palliative RT for bone metastasis. Nonetheless, single-fraction RT remains relatively uncommon. Participating in GOC discussions with a radiation oncologist is associated with higher rates of hospice referral. Inpatient status at consultation is associated with short survival.

Method and apparatus for positioning a beam of charged particles

International Nuclear Information System (INIS)

Michail, M.S.; Woodard, O.C.; Yourke, H.S.

1975-01-01

A beam of charged particles is stepped from one predetermined position to another to form a desired pattern on a semiconductor wafer. There is a dynamic correction for the deviation of the actual position of the beam from its predetermined position, so that the beam is applied to the deviated position rather than the predetermined position. Through the location of four registration marks, the writing field is precisely defined. Writing fields may be interconnected by the sharing of registration marks, enabling the construction of chips which are larger than a single writing field. (auth)

Triple GEM gas detectors as real time fast neutron beam monitors for spallation neutron sources

International Nuclear Information System (INIS)

Murtas, F; Claps, G; Croci, G; Tardocchi, M; Pietropaolo, A; Cippo, E Perelli; Rebai, M; Gorini, G; Frost, C D; Raspino, D; Rhodes, N J; Schooneveld, E M

2012-01-01

A fast neutron beam monitor based on a triple Gas Electron Multiplier (GEM) detector was developed and tested for the ISIS spallation neutron source in U.K. The test on beam was performed at the VESUVIO beam line operating at ISIS. The 2D fast neutron beam footprint was recorded in real time with a spatial resolution of a few millimeters thanks to the patterned detector readout.

Site-specific forest-assembly of single-wall carbon nanotubes on electron-beam patterned SiOx/Si substrates

International Nuclear Information System (INIS)

Wei Haoyan; Kim, Sang Nyon; Kim, Sejong; Huey, Bryan D.; Papadimitrakopoulos, Fotios; Marcus, Harris L.

2008-01-01

Based on electron-beam direct writing on the SiO x /Si substrates, favorable absorption sites for ferric cations (Fe 3+ ions) were created on the surface oxide layer. This allowed Fe 3+ -assisted self-assembled arrays of single-wall carbon nanotube (SWNT) probes to be produced. Auger investigation indicated that the incident energetic electrons depleted oxygen, creating more dangling bonds around Si atoms at the surface of the SiO x layer. This resulted in a distinct difference in the friction forces from unexposed regions as measured by lateral force microscopy (LFM). Atomic force microscopy (AFM) affirmed that the irradiated domains absorbed considerably more Fe 3+ ions upon immersion into pH 2.2 aqueous FeCl 3 solution. This rendered a greater yield of FeO(OH)/FeOCl precipitates, primarily FeO(OH), upon subsequent washing with lightly basic dimethylformamide (DMF) solution. Such selective metal-functionalization established the basis for the subsequent patterned forest-assembly of SWNTs as demonstrated by resonance Raman spectroscopy

Analytic models for beam propagation and far-field patterns in slab and bow-tie x-ray lasers

International Nuclear Information System (INIS)

Chandler, E.A.

1994-06-01

Simplified analytic models for beam propagation in slab and bow-tie x-ray lasers yield convenient expressions that provide both a framework for guidance in computer modeling and useful approximates for experimenters. In unrefracted bow-tie lasers, the laser shape in conjunction with the nearly-exponential weighting of rays according to their length produces a small effective aperture for the signal. We develop an analytic expression for the aperture and the properties of the far-field signal. Similarly, we develop the view that the far-field pattern of refractive slab lasers is the result of effective apertures that are created by the interplay of refraction and exponential amplification. We present expressions for the size of this aperture as a function of laser parameters as well as for the intensity and position of the far-field lineout. This analysis also yields conditions for the refraction limit in slab lasers and an estimate for the signal loss due to refraction

Modification of Surface Energy via Direct Laser Ablative Surface Patterning

Science.gov (United States)

Wohl, Christopher J., Jr. (Inventor); Belcher, Marcus A. (Inventor); Connell, John W. (Inventor); Hopkins, John W. (Inventor)

2015-01-01

Surface energy of a substrate is changed without the need for any template, mask, or additional coating medium applied to the substrate. At least one beam of energy directly ablates a substrate surface to form a predefined topographical pattern at the surface. Each beam of energy has a width of approximately 25 micrometers and an energy of approximately 1-500 microJoules. Features in the topographical pattern have a width of approximately 1-500 micrometers and a height of approximately 1.4-100 micrometers.

A new method for generating axially-symmetric and radially-polarized beams

International Nuclear Information System (INIS)

Niu Chunhui; Gu Benyuan; Dong Bizhen; Zhang Yan

2005-01-01

A scheme for generating axially-symmetric and radially-polarized beams is proposed by using two diffractive phase elements (DPEs) made of birefringent materials. The design of these two DPEs is based on the general theory of phase-retrieval of optical system in combination with an iterative algorithm. The first DPE is used for demultiplexing two orthogonally linearly-polarized light beams to produce diffractive patterns, and the second DPE is used for compensating the phase difference to obtain the desired radially-polarized beam

The effect of CFRP on retrofitting of damaged HSRC beams using AE technique

Science.gov (United States)

Soffian Noor, M. S.; Noorsuhada, M. N.

2017-12-01

This paper presents the effect of carbon fibre reinforced polymer (CFRP) on retrofitted high strength reinforced concrete (HSRC) beams using acoustic emission (AE) technique. Two RC beam parameters were prepared. The first was the control beam which was undamaged HSRC beam. The second was the damaged HSRC beam retrofitted with CFRP on the soffit. The main objective of this study is to assess the crack modes of HSRC beams using AE signal strength. The relationship between signal strength, load and time were analysed and discussed. The crack pattern observed from the visual observation was also investigated. HSRC beam retrofitted with CFRP produced high signal strength compared to control beam. It demonstrates the effect of the AE signal strength for interpretation and prediction of failure modes that might occur in the beam specimens.

Focused ion beam machining and deposition for nanofabrication

Energy Technology Data Exchange (ETDEWEB)

Davies, S T; Khamsehpour, B [Warwick Univ., Coventry (United Kingdom). Dept. of Engineering

1996-05-01

Focused ion beam micromatching (FIBM) and focused ion beam deposition (FIBD) enable spatially selective, maskless, patterning and processing of materials at extremely high levels of resolution. State-of-the-art focused ion beam (FIB) columns based on high brightness liquid metal ion source (LMIS) technology are capable of forming probes with dimensions of order 10 nm with a lower limit on spot size set by the inherent energy spread of the LMIS and the chromatic aberration of ion optical systems. The combination of high lateral and depth resolution make FIBM and FIBD powerful tools for nanotechnology applications. In this paper we present some methods of controlling FIBM and FIBD processes for nanofabrication purposes and discuss their limitations. (author).

Water soluble and metal-containing electron beam resist poly(sodium 4-styrenesulfonate)

International Nuclear Information System (INIS)

Abbas, Arwa Saud; Alqarni, Sondos; Shokouhi, Babak Baradaran; Yavuz, Mustafa; Cui, Bo

2014-01-01

Popular electron beam resists such as PMMA, ZEP and HSQ all use solvent or base solutions for processing, which may attack the sub-layers or substrate that are made out of organic semiconducting materials. In this study we show that water soluble poly(sodium 4-styrenesulfonate), or sodium PSS, can be used as a negative electron beam resist developed in water. Moreover, since PSS contains metal sodium, its dry etching resistance is much higher than PMMA. It is notable that sodium PSS’s sensitivity and contrast is still far inferior to organic resists such as PMMA, thus it is not suitable for patterning dense and high-resolution structures. Nevertheless, feature size down to 40 nm was achieved for sparse patterns. Lastly, using very low energy (here 2 keV) electron beam lithography and liftoff process using water only, patterning of metal layer on an organic conductive material P3HT was achieved. The metallization of an organic conducting material may find applications in organic semiconductor devices such as OLED. (paper)

ArF photo resist pattern sample preparation method using FIB without protective coating

Science.gov (United States)

Okushima, Hirohisa; Onozuka, Toshihiko; Kuroda, Yasushi; Yaguchi, Toshie; Umemura, Kaoru; Tamochi, Ryuichiro; Watanabe, Kenji; Hasegawa, Norio; Kawata, Isao; Rijpers, Bart

2006-03-01

This paper presents a novel method of FIB (FIB: focused ion beam) sample preparation to accurately evaluate critical dimensions and profiles of ArF photo resist patterns without the use of a protective coating on the photo resist. In order to accomplish this, the FIB micro-sampling method that is one of effective FIB milling and fabrication method was employed. First a Si cap is picked up from a silicon wafer and fixed to ArF photo resist patterns to protect against ion beam irradiation. Then, a micro-sample, a piece of Si-capped ArF photo resist, was extracted from the bulk ArF photo resist. In this procedure, this silicon cap always protects ArF photo resist patterns against ion beam irradiation. For the next step, the micro-sample is fixed to a needle stub of the FIB-STEM (STEM: scanning transmission electron microscopy) compatible rotation holder. This sample on the needle stub was rotated 180 degrees and milled from the side of Si substrate. Lastly, the sample is milled to the thickness of 2μm. In this process, the ion beam is irradiating from the silicon substrate side to minimize the ion beam irradiation damages on the ArF photo resist patterns. EDX (EDX: Energy dispersive X-ray spectroscopy) analysis proved that no gallium ions were detected on the surface of the ArF photo resist patterns. The feasibility of high accelerating voltage observation of STEM to observe line edge roughness of a thick sample like 2μm without shrinkage has been demonstrated.

Surface engineering with ion beams: from self-organized nanostructures to ultra-smooth surfaces

International Nuclear Information System (INIS)

Frost, F.; Ziberi, B.; Schindler, A.; Rauschenbach, B.

2008-01-01

Low-energy ion-beam sputtering, i.e. the removal of atoms from a surface due to the impact of energetic ions or atoms, is an inherent part of numerous surface processing techniques. Besides the actual removal of material, this surface erosion process often results in a pronounced alteration of the surface topography. Under certain conditions, sputtering results in the formation of well-ordered patterns. This self-organized pattern formation is related to a surface instability between curvature-dependent sputtering that roughens the surface and smoothing by different surface relaxation mechanisms. If the evolution of surface topography is dominated by relaxation mechanisms, surface smoothing can occur. In this presentation the current status of self-organized pattern formation and surface smoothing by low-energy ion-beam erosion of Si and Ge is summarized. In detail it will be shown that a multitude of patterns as well as ultra-smooth surfaces can develop, particularly on Si surfaces. Additionally, the most important experimental parameters that control these processes are discussed. Finally, examples are given for the application of low-energy ion beams as a novel approach for passive optical device engineering for many advanced optical applications. (orig.)

Integral momenta of vortex Bessel-Gaussian beams in turbulent atmosphere.

Science.gov (United States)

Lukin, Igor P

2016-04-20

The orbital angular momentum of vortex Bessel-Gaussian beams propagating in turbulent atmosphere is studied theoretically. The field of an optical beam is determined through the solution of the paraxial wave equation for a randomly inhomogeneous medium with fluctuations of the refraction index of the turbulent atmosphere. Peculiarities in the behavior of the total power of the vortex Bessel-Gaussian beam at the receiver (or transmitter) are examined. The dependence of the total power of the vortex Bessel-Gaussian beam on optical beam parameters, namely, the transverse wave number of optical radiation, amplitude factor radius, and, especially, topological charge of the optical beam, is analyzed in detail. It turns out that the mean value of the orbital angular momentum of the vortex Bessel-Gaussian beam remains constant during propagation in the turbulent atmosphere. It is shown that the variance of fluctuations of the orbital angular momentum of the vortex Bessel-Gaussian beam propagating in turbulent atmosphere calculated with the "mean-intensity" approximation is equal to zero identically. Thus, it is possible to declare confidently that the variance of fluctuations of the orbital angular momentum of the vortex Bessel-Gaussian beam in turbulent atmosphere is not very large.

Low grade gliomas: preliminary analysis of failure patterns among patients treated using 3D conformal external beam irradiation

International Nuclear Information System (INIS)

Pu, Anthony T.; Sandler, Howard M.; Radany, Eric H.; Blaivas, Mila; Page, Michaelyn A.; Greenberg, Harry S.; Junck, Larry; Ross, Donald A.

1995-01-01

Purpose: The pattern of failure of low grade gliomas following radiotherapy is less well known than that of the high grade gliomas. Stereotactic histologic studies have suggested that tumor cells extend beyond imaging abnormalities, and that large margins would be required for radiotherapy target volumes to encompass all of the neoplasm. Our experience using computerized tomography (CT)- and magnetic resonance (MR)-planned irradiation of low grade gliomas was reviewed to determine the pattern of tumor recurrence, in an effort to clinically define the minimum margin required. Methods and Materials: Forty-six patients with low grade supratentorial gliomas were treated between April 1985 and November 1992 using three-dimensional (3D) conformal CT- or MR-planned external beam radiotherapy. Fields were designed to encompass a target volume created by adding a margin to the tumor in three dimensions. Generally, patients were treated using shrinking fields with an initial target (tumor plus a 1 to 3 cm margin) treated to a dose of 45 to 50.4 (median 50.4) Gy, and a boost (tumor plus a 0 to 2 cm margin) treated to a total of 54 to 59.4 (median 59.4) Gy. Median follow-up was 32.9 months. Results: There have been 11 failures; all of these occurred within the radiographic abnormality (either T2 prolongation or CT hypodensity) visualized at the time of treatment planning (i.e., all failures were within the boost volume). Median time to failure was 53 months. Because all failures were local, there was no relationship between the amount by which the tumor volumes were expanded to create target volumes and the eventual outcome. Conclusion: Despite pathologic data suggesting that low grade glioma cells can be found outside the MR T2-signal abnormality in many cases, our results demonstrate that conformal external beam radiotherapy, in which the high dose volume is limited, does not result in increased marginal or out-of-field failures. Until control of tumor within the

What Can a Dual beam Really Do?

International Nuclear Information System (INIS)

Lawrence, P.

2005-01-01

Full Text: Smallstage Dualbeam (SDB) systems, that is a Focussed Ion Beam column coupled with a SEM column, have been around for about five years now. There impact on the Semiconductor industry has been enormous, with virtually every lab having a SDB to produce, characterise and analyse cross sections and TEM samples on the Nano-scale. But what about other industries? What else can SDB system be used for? The SEM column in itself is a very powerful tool for sample characterisation, modification and analysis. An electron beam from a Tungsten or Thermal Field Emission source has enough current to allow sophisticated patterns to be created in photo-resist samples, a process known as lithography. The current is also high enough to allow for a process known as Electron Beam Induced Deposition (EBID), where the beam interacts with an introduced gas and material is deposited in a controlled manner on the sample. With the addition of the Focussed Ion Beam (FIB) direct removal of material from a samples becomes possible. Focussed Ga + ions are scanned in controlled patterns over the specimen and material is removed rapidly and effectively. The FIB also allows deposition in a similar way to EBID, but on a much larger scale. The FIB also has imaging properties not available with a SEM. As ions are large they are channelled in the grains of certain materials and this results in channelling contrast, a feature which can be used to determine crystal orientation. Combing a SEM and FIB column in the form of a SDB results in a very powerful tool which has many applications outside it's original design purpose. As the cost of these tools becomes more attractive, the potential for even greater diversification of applications is apparent. (Author)

High-power laser delocalization in plasmas leading to long-range beam merging

Energy Technology Data Exchange (ETDEWEB)

Nakatsutsumi, M; Marques, J R; Antici, P; Bourgeois, N; Romagnani, L; Audebert, P; Fuchs, J [UPMC, CEA, CNRS, LULI, Ecole Polytech, F-91128 Palaiseau (France); Nakatsutsumi, M; Kodama, R [Osaka Univ, Grad Sch Engn, Suita, Osaka 5650871 (Japan); Antici, P [Univ Roma La Sapienza, Dipartimento SBAI, I-00161 Rome (Italy); Feugeas, J L; Nicolai, P [Univ Bordeaux 1, CNRS, CEA, Ctr Lasers Intenses and Applicat, F-33405 Talence (France); Lin, T [Fox Chase Canc Ctr, Philadelphia, PA 19111 (United States)

2010-07-01

Attraction and fusion between co-propagating light beams, mutually coherent or not, can take place in nonlinear media as a result of the beam power modifying the refractive index of the medium. In the context of high-power light beams, induced modifications of the beam patterns could potentially impact many topics, including long-range laser propagation, the study of astrophysical colliding blast waves and inertial confinement fusion. Here, through experiments and simulations, we show that in a fully ionized plasma, which is a nonlinear medium, beam merging can take place for high-power and mutually incoherent beams that are initially separated by several beam diameters. This is in contrast to the usual assumption that this type of interaction is limited to beams separated by only one beam diameter. This effect, which is orders of magnitude more significant than Kerr-like nonlinearity in gases, demonstrates the importance of potential cross-talk amongst multiple beams in plasma. (authors)

Latitudinal beaming of Jupiter's low frequency radio emissions

International Nuclear Information System (INIS)

Alexander, J.K.; Desch, M.D.; Kaiser, M.L.; Thieman, J.R.

1979-01-01

By comparing Rae 1 and Imp 6 satelite measurements of Jupiter's radio emissions near 1 MHz with recent Voyager 1 and 2 observations in the same frequency range it is now possible to study the properties of the low frequency radiation pattern over a 10 0 range of latitudes with respect to the Jovian rotation equator. These observations, which cover a wider latitudinal range than is possible from the earth, are consistent with many aspect of earlier ground-based measurements that have been used to infer a sharp beaming pattern for the decameter wavelength emissions. We find marked, systematic changes in the statistical occurrence probability distributions with system III central meridian longitude as the Jovigraphic latitude of the observer changes over this range. Moreover, simultaneous observations by the two Voyager spacecraft, which are separated by up to 3 0 in Jovigraphic latitude, suggest that the instantaneous beam width may be no more than a few degrees at times. The new hectometer wave results can be interpreted in terms of a narrow, curved sheet at a fixed magnetic latitude into which the emission is beamed to escape the planet

Pulsar signals from relativistic electron beams

International Nuclear Information System (INIS)

Elsaesser, K.; Kirk, J.

1976-01-01

The possibility of the radio emission from pulsars originating in a beam-plasma system is discussed. We calculate the curvature radiation which arises if this system is placed in a very strong curved magnetic field. Numerical experiments show that the beam instability evolves into a rather stationary wave pattern whose Fourier components are concentrated near the most unstable mode. This result leads us to estimates of the radiation intensity of its autocorrelation function in time, and its bandwidth. The results are compared with measurements of the micro-structure of pulses, and the constraints imposed on radiation mechanisms by longer time-scale properties are shown to be satisfied. (orig.) [de

Influence of Connection Placement to the Behavior of Precast Concrete Exterior Beam-Column Joint

Directory of Open Access Journals (Sweden)

Elly Tjahjono

2010-10-01

Full Text Available This paper presents an experimental study on the influence of connection placement to the behaviour of exterior beamcolumn joint of precast concrete structure under semi cyclic loading. Four half-scale beam-column specimens were investigated. Three beam-columns were jointed through connection that are placed in beam-column joint region and the forth is connected at the plastic hinge potensial region of the beam. Crack patterns, strength, stiffness and ductility of the test specimens have been evaluated. The test result indicated that all beam-column specimens show good ductility behavior.

An approach towards solving refraction problems in EM1002 multi-beam echo-sounder system

Digital Repository Service at National Institute of Oceanography (India)

Fernandes, W.A.

Multi-beam echo-sounding is the technique in which multiple beams of acoustic in nature are sent down to seabed and upon reflection, they are received back and processed to give depths values. The report is focused to give a brief idea about EM1002...

Influence of Connection Placement to the Behavior of Precast Concrete Exterior Beam-Column Joint

OpenAIRE

Elly Tjahjono; Heru Purnomo

2010-01-01

This paper presents an experimental study on the influence of connection placement to the behaviour of exterior beamcolumn joint of precast concrete structure under semi cyclic loading. Four half-scale beam-column specimens were investigated. Three beam-columns were jointed through connection that are placed in beam-column joint region and the forth is connected at the plastic hinge potensial region of the beam. Crack patterns, strength, stiffness and ductility of the test specimens have been...

Exposure parameters in proton beam writing for hydrogen silsesquioxane

International Nuclear Information System (INIS)

Kan, J.A. van; Zhang, F.; Zhang, C.; Bettiol, A.A.; Watt, F.

2008-01-01

In proton beam writing (PBW) a focused MeV proton beam is scanned in a predetermined pattern over a resist (e.g. PMMA, SU-8 or HSQ), which is subsequently chemically developed. In e-beam writing as well as p-beam writing the energy loss of the primary beam is dominated by energy transfer to substrate electrons. Unlike the high energy secondary electrons generated during e-beam writing the secondary electrons induced by the primary proton beam have low energy and therefore a limited range, resulting in minimal proximity effects. The low proximity effects exhibited by p-beam writing coupled with the straight trajectory and high penetration of the proton beam enables the production of high aspect ratio, high density 3D micro and nanostructures with well defined smooth side walls to be directly written into resist materials. This property together with the stability and focusing power of the end station ensures even exposures with nm smoothness and allows fabrication of details down to the 20 nm level. In this paper, we present results like contrast and sensitivity for PBW using, hydrogen silsesquioxane (HSQ) and XR-1541, both are non-C based resists. Unlike PMMA and SU-8 resist HSQ shows aging effects, requiring optimized processing parameters in PBW

Strengthening and repairing of damaged concrete beams

International Nuclear Information System (INIS)

Mahmoud, M.K.; Ebrahiem, G.T.A.; Hassanein, S.A.

2005-01-01

The main part in this investigation is concerned with the advanced techniques of retrofitting damaged reinforced concrete (RC) beams. Glass fiber reinforced plastics (GFRP) were employed for this purpose. The aim of this paper is to investigate the advantage of using glass fiber .reinforced plastics (GFRP) to retrofit and repair damaged reinforced concrete beams. In this investigation, concrete beam specimens were preloaded up to the 60%, 70% arid 80% of their ultimate load capacity. The damaged beams were then repaired with one layer of FRP composite wraps and re-tested. Plastic reinforced by glass fibers 20% fiber volume fractions and with various fiber arrangement unidirectional, bi-directional and chopped were also considered. Four points bending test was adopted. The bending tests were performed on fourteen RC beams in addition to a two control, all of them were (225 30 15) cm in dimensions, and with a typical reinforcement details. Test results were indicative of the merit of using GFRP, as the ultimate loads were almost restored and the modes of failure were of ductile nature. Even more an increase in the ultimate bearing capacity was recorded for some of the retrofitted beams. The effects of the previously mentioned parameters on the cracking pattern and failure mode were reported and thoroughly discussed

Interaction between corrosion crack width and steel loss in RC beams corroded under load

International Nuclear Information System (INIS)

Malumbela, Goitseone; Alexander, Mark; Moyo, Pilate

2010-01-01

This paper presents results and discussions on an experimental study conducted to relate the rate of widening of corrosion cracks with the pattern of corrosion cracks as well as the level of steel corrosion for RC beams (153 x 254 x 3000 mm) that were corroded whilst subjected to varying levels of sustained loads. Steel corrosion was limited to the tensile reinforcement and to a length of 700 mm at the centre of the beams. The rate of widening of corrosion cracks as well as strains on uncracked faces of RC beams was constantly monitored during the corrosion process, along the corrosion region and along other potential cracking faces of beams using a demec gauge. The distribution of the gravimetric mass loss of steel along the corrosion region was measured at the end of the corrosion process. The results obtained showed that: the rate of widening of each corrosion crack is dependent on the overall pattern of the cracks whilst the rate of corrosion is independent of the pattern of corrosion cracks. A mass loss of steel of 1% was found to induce a corrosion crack width of about 0.04 mm.

Fast‐writing E‐beam for defining large arrays of nano‐holes

DEFF Research Database (Denmark)

Højlund-Nielsen, Emil; Clausen, Jeppe Sandvik; Christiansen, Alexander Bruun

2013-01-01

Efficient nanoscale patterning of large areas is required for sub-wavelength optics. For example, 200 nm periodic structures are often too small to be made with standard UV- and DUV-equipment. Still, the final product must be made at an economic cost. Here we use a fast-writing strategy described...... in [1], where electron beam lithography (EBL) with a focused Gaussian beam is used to define shapes directly. The serial technique is optimized for speed and pattern fidelity to a maximum writing speed of around 30 min/cm2 for 200 nm periods in 2D lattices. The overall costs in terms of machine time...

Tongue-driven sonar beam steering by a lingual-echolocating fruit bat.

Directory of Open Access Journals (Sweden)

Wu-Jung Lee

2017-12-01

Full Text Available Animals enhance sensory acquisition from a specific direction by movements of head, ears, or eyes. As active sensing animals, echolocating bats also aim their directional sonar beam to selectively "illuminate" a confined volume of space, facilitating efficient information processing by reducing echo interference and clutter. Such sonar beam control is generally achieved by head movements or shape changes of the sound-emitting mouth or nose. However, lingual-echolocating Egyptian fruit bats, Rousettus aegyptiacus, which produce sound by clicking their tongue, can dramatically change beam direction at very short temporal intervals without visible morphological changes. The mechanism supporting this capability has remained a mystery. Here, we measured signals from free-flying Egyptian fruit bats and discovered a systematic angular sweep of beam focus across increasing frequency. This unusual signal structure has not been observed in other animals and cannot be explained by the conventional and widely-used "piston model" that describes the emission pattern of other bat species. Through modeling, we show that the observed beam features can be captured by an array of tongue-driven sound sources located along the side of the mouth, and that the sonar beam direction can be steered parsimoniously by inducing changes to the pattern of phase differences through moving tongue location. The effects are broadly similar to those found in a phased array-an engineering design widely found in human-made sonar systems that enables beam direction changes without changes in the physical transducer assembly. Our study reveals an intriguing parallel between biology and human engineering in solving problems in fundamentally similar ways.

Burnout experiment in subcooled forced-convection boiling of water for beam dumps of a high power neutral beam injector

International Nuclear Information System (INIS)

Horiike, Hiroshi; Kuriyama, Masaaki; Morita, Hiroaki

1982-01-01

Experimental studies were made on burnout heat flux in highly subcooled forced-convection boiling of water for the design of beam dumps of a high power neutral beam injector for Japan Atomic Energy Research Institute Tokamak-60. These dumps are composed of many circular tubes with two longitudinal fins. The tube was irradiated with nonuniformly distributed hydrogen ion beams of 120 to 200 kW for as long as 10 s. The coolant water was circulated at flow velocities of 3 to 7.5 m/s at exit pressures of 0.4 to 0.9 MPa. The burnout and film-boiling data were obtained at local heat fluxes of 8 to 15 MW/m 2 . These values were as high as 2.5 times larger than those for the circumferentially uniform heat flux case with the same parameters. These data showed insensitivity to local subcooling as well as to pressure, and simple burnout correlations were derived. From these results, the beam dumps have been designed to receive energetic beam fluxes of as high as 5 MW/m 2 with a margin of a factor of 2 for burnout

Beam-Beam Interaction Studies at LHC

CERN Document Server

Schaumann, Michaela; Alemany Fernandez, R

2011-01-01

The beam-beam force is one of the most important limiting factors in the performance of a collider, mainly in the delivered luminosity. Therefore, it is essential to measure the effects in LHC. Moreover, adequate understanding of LHC beam-beam interaction is of crucial importance in the design phases of the LHC luminosity upgrade. Due to the complexity of this topic the work presented in this thesis concentrates on the beam-beam tune shift and orbit effects. The study of the Linear Coherent Beam-Beam Parameter at the LHC has been determined with head-on collisions with small number of bunches at injection energy (450 GeV). For high bunch intensities the beam-beam force is strong enough to expect orbit effects if the two beams do not collide head-on but with a crossing angle or with a given offset. As a consequence the closed orbit changes. The closed orbit of an unperturbed machine with respect to a machine where the beam-beam force becomes more and more important has been studied and the results are as well ...

Metallized ceramic vacuum pipe for particle beams

International Nuclear Information System (INIS)

Butler, B.L.; Featherby, M.

1990-01-01

A ceramic vacuum chamber segment in the form of a long pipe of rectangular cross section has been assembled from standard shapes of alumina ceramic using glass bonding techniques. Prior to final glass bonding, the internal walls of the pipe are metallized using an electroplating technology. These advanced processes allow for precision patterning and conductivity control of surface conducting films. The ability to lay down both longitudinal and transverse conductor patterns separated by insulating layers of glass give the accelerator designer considerable freedom in tailoring longitudinal and transverse beam pipe impedances. Assembly techniques of these beam pipes are followed through two iterations of semi-scale pipe sections made using candidate materials and processes. These demonstrate the feasibility of the concepts and provide parts for electrical characterization and for further refinement of the approach. In a parallel effort, a variety of materials, joining processes and assembly procedures have been tried to assure flexibility and reliability in the construction of 10-meter long sections to any required specifications

Decreasing of pulsation intensity levels in X-ray receivers

CERN Document Server

Dvoryankin, V F; Kudryashov, A A; Petrov, A G

2002-01-01

The low frequency filter is applied in the multichannel receiver on the basis of the GaAs epitaxial structures for decreasing the pulsations level at the signals amplifier outlet. The optimal band of the filter is determined by the transition processes by the detector scanning in the roentgen beams. The X-ray source of radiation with the medium-frequency feeding generator is used for verifying the quality of the obtained X-ray image

Transient beam loading in the ALS harmonic RF system

International Nuclear Information System (INIS)

Byrd, J.; De Santis, S.; Georgsson, M.; Stover, G.; Fox, J.; Prabhakar, S.; Teytelman, D.

2000-01-01

We report on the commissioning of a higher harmonic radiofrequency system at the Advanced Light Source, designed to improve the beam lifetime. We have achieved an increase above a factor of two in our best results up to now. Transient beam loading of the harmonic cavities, due to the unequal fill patterns, creates the greatest limitation on lifetime improvement. We also describe several interesting effects on the operation of the longitudinal and transverse multibunch feedback system

Treatment of basal cell epithelioma with high energy electron beam

Energy Technology Data Exchange (ETDEWEB)

Ogawa, Y. (Hyogo-ken Cancer Center, Kobe (Japan)); Kumano, M.; Kumano, K.

1981-11-01

Thirty patients with basal cell epithelioma received high energy electron beam therapy. They were irradiated with a dose ranging from 4,800 rad (24 fractions, 35 days) to 12,000 rad (40 fractions, 57 days). Tumors disappeared in all cases. These were no disease-related deaths; in one patient there was recurrence after 2 years. We conclude that radiotherapy with high energy electron beam is very effective in the treatment of basal cell epithelioma.

Coding and decoding in a point-to-point communication using the polarization of the light beam.

Science.gov (United States)

Kavehvash, Z; Massoumian, F

2008-05-10

A new technique for coding and decoding of optical signals through the use of polarization is described. In this technique the concept of coding is translated to polarization. In other words, coding is done in such a way that each code represents a unique polarization. This is done by implementing a binary pattern on a spatial light modulator in such a way that the reflected light has the required polarization. Decoding is done by the detection of the received beam's polarization. By linking the concept of coding to polarization we can use each of these concepts in measuring the other one, attaining some gains. In this paper the construction of a simple point-to-point communication where coding and decoding is done through polarization will be discussed.

Effects of laser fluence on silicon modification by four-beam laser interference

International Nuclear Information System (INIS)

Zhao, Le; Li, Dayou; Wang, Zuobin; Yue, Yong; Zhang, Jinjin; Yu, Miao; Li, Siwei

2015-01-01

This paper discusses the effects of laser fluence on silicon modification by four-beam laser interference. In this work, four-beam laser interference was used to pattern single crystal silicon wafers for the fabrication of surface structures, and the number of laser pulses was applied to the process in air. By controlling the parameters of laser irradiation, different shapes of silicon structures were fabricated. The results were obtained with the single laser fluence of 354 mJ/cm 2 , 495 mJ/cm 2 , and 637 mJ/cm 2 , the pulse repetition rate of 10 Hz, the laser exposure pulses of 30, 100, and 300, the laser wavelength of 1064 nm, and the pulse duration of 7–9 ns. The effects of the heat transfer and the radiation of laser interference plasma on silicon wafer surfaces were investigated. The equations of heat flow and radiation effects of laser plasma of interfering patterns in a four-beam laser interference distribution were proposed to describe their impacts on silicon wafer surfaces. The experimental results have shown that the laser fluence has to be properly selected for the fabrication of well-defined surface structures in a four-beam laser interference process. Laser interference patterns can directly fabricate different shape structures for their corresponding applications

Focused Ion Beam Methods for Research and Control of HEMT Fabrication

Science.gov (United States)

Pevtsov, E. Ph; Bespalov, A. V.; Demenkova, T. A.; Luchnikov, P. A.

2017-04-01

The combination of ion-beam spraying and raster electronic microscopy allows to receive images of sections of defects of the growth nature origin in epitaxial films on GaN basis with nanodimensional permission, to carry out their analysis and classification irrespective of conditions of receiving. Results of application of the specified methods for the analysis of technological operations when forming the microwave transistors are considered: formations of locks, receiving of holes and drawing of contacts.

Vibration piezoelectric energy harvester with multi-beam

Energy Technology Data Exchange (ETDEWEB)

Cui, Yan, E-mail: yanc@dlut.edu.cn; Zhang, Qunying, E-mail: zhangqunying89@126.com; Yao, Minglei, E-mail: yaomingleiok@126.com [Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education, Dalian University of Technology, 116024, Dalian, Liaoning Province (China); Dong, Weijie, E-mail: dongwj@dlut.edu.cn [School of Electronic and Information Engineering, Dalian University of Technology, 116024, Dalian, Liaoning Province (China); Gao, Shiqiao, E-mail: gaoshq@bit.edu.cn [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, 100081, Beijing Province (China)

2015-04-15

This work presents a novel vibration piezoelectric energy harvester, which is a micro piezoelectric cantilever with multi-beam. The characteristics of the PZT (Pb(Zr{sub 0.53}Ti{sub 0.47})O{sub 3}) thin film were measured; XRD (X-ray diffraction) pattern and AFM (Atomic Force Microscope) image of the PZT thin film were measured, and show that the PZT (Pb(Zr{sub 0.53}Ti{sub 0.47})O{sub 3}) thin film is highly (110) crystal oriented; the leakage current is maintained in nA magnitude, the residual polarisation Pr is 37.037 μC/cm{sup 2}, the coercive field voltage Ec is 27.083 kV/cm, and the piezoelectric constant d{sub 33} is 28 pC/N. In order to test the dynamic performance of the energy harvester, a new measuring system was set up. The maximum output voltage of the single beam of the multi-beam can achieve 80.78 mV under an acceleration of 1 g at 260 Hz of frequency; the maximum output voltage of the single beam of the multi-beam is almost 20 mV at 1400 Hz frequency. .

Arbitrary beam control using passive lossless metasurfaces enabled by orthogonally polarized custom surface waves

Science.gov (United States)

Kwon, Do-Hoon; Tretyakov, Sergei A.

2018-01-01

For passive, lossless impenetrable metasurfaces, a design technique for arbitrary beam control of receiving, guiding, and launching is presented. Arbitrary control is enabled by a custom surface wave in an orthogonal polarization such that its addition to the incident (input) and the desired scattered (output) fields is supported by a reactive surface impedance everywhere on the reflecting surface. Such a custom surface wave (SW) takes the form of an evanescent wave propagating along the surface with a spatially varying envelope. A growing SW appears when an illuminating beam is received. The SW amplitude stays constant when power is guided along the surface. The amplitude diminishes as a propagating wave (PW) is launched from the surface as a leaky wave. The resulting reactive tensor impedance profile may be realized as an array of anisotropic metallic resonators printed on a grounded dielectric substrate. Illustrative design examples of a Gaussian beam translator-reflector, a probe-fed beam launcher, and a near-field focusing lens are provided.

Joint random beam and spectrum selection for spectrum sharing systems with partial channel state information

KAUST Repository

Abdallah, Mohamed M.

2013-11-01

In this work, we develop joint interference-aware random beam and spectrum selection scheme that provide enhanced performance for the secondary network under the condition that the interference observed at the primary receiver is below a predetermined acceptable value. We consider a secondary link composed of a transmitter equipped with multiple antennas and a single-antenna receiver sharing the same spectrum with a set of primary links composed of a single-antenna transmitter and a single-antenna receiver. The proposed schemes jointly select a beam, among a set of power-optimized random beams, as well as the primary spectrum that maximizes the signal-to-interference-plus-noise ratio (SINR) of the secondary link while satisfying the primary interference constraint. In particular, we consider the case where the interference level is described by a q-bit description of its magnitude, whereby we propose a technique to find the optimal quantizer thresholds in a mean square error (MSE) sense. © 2013 IEEE.

Joint random beam and spectrum selection for spectrum sharing systems with partial channel state information

KAUST Repository

Abdallah, Mohamed M.; Sayed, Mostafa M.; Alouini, Mohamed-Slim; Qaraqe, Khalid A.

2013-01-01

In this work, we develop joint interference-aware random beam and spectrum selection scheme that provide enhanced performance for the secondary network under the condition that the interference observed at the primary receiver is below a predetermined acceptable value. We consider a secondary link composed of a transmitter equipped with multiple antennas and a single-antenna receiver sharing the same spectrum with a set of primary links composed of a single-antenna transmitter and a single-antenna receiver. The proposed schemes jointly select a beam, among a set of power-optimized random beams, as well as the primary spectrum that maximizes the signal-to-interference-plus-noise ratio (SINR) of the secondary link while satisfying the primary interference constraint. In particular, we consider the case where the interference level is described by a q-bit description of its magnitude, whereby we propose a technique to find the optimal quantizer thresholds in a mean square error (MSE) sense. © 2013 IEEE.

Beam-beam phenomenology

International Nuclear Information System (INIS)

Teng, L.C.

1980-01-01

In colliding beam storage rings the beam collision regions are generally so short that the beam-beam interaction can be considered as a series of evenly spaced non-linear kicks superimposed on otherwise stable linear oscillations. Most of the numerical studies on computers were carried out in just this manner. But for some reason this model has not been extensively employed in analytical studies. This is perhaps because all analytical work has so far been done by mathematicians pursuing general transcendental features of non-linear mechanics for whom this specific model of the specific system of colliding beams is too parochial and too repugnantly physical. Be that as it may, this model is of direct interest to accelerator physicists and is amenable to (1) further simplification, (2) physical approximation, and (3) solution by analogy to known phenomena

Thermal problems on high flux beam lines

International Nuclear Information System (INIS)

Avery, R.T.

1983-09-01

Wiggler and undulator magnets can provide very intense photon flux densities to beam line components. This paper addresses some thermal/materials consequences due to such impingement. The LBL/Exxon/SSRL hybrid-wiggler Beam Line VI now nearing operation will be able to provide up to approx. 7 kW of total photon power at planned SPEAR operating conditions. The first masks are located at 6.5 meters from the source and may receive a peak power density (transverse to the beam) exceeding 20 kW/cm 2 . Significantly, this heat transfer rate exceeds that radiated from the sun's surface (7 kW/cm 2 ) and is comparable to that of welding torches. Clearing, cooling and configuration are of critical importance. Configurations for the first fixed mask, the movable mask, and the pivot mask on this beam line are presented together with considerations of thermal stress fatigue and of heat transfer by conduction to water-cooling circuits. Some preliminary information on heating of crystals and mirrors is also presented

A Monte Carlo code for ion beam therapy

CERN Multimedia

Anaïs Schaeffer

2012-01-01

Initially developed for applications in detector and accelerator physics, the modern Fluka Monte Carlo code is now used in many different areas of nuclear science. Over the last 25 years, the code has evolved to include new features, such as ion beam simulations. Given the growing use of these beams in cancer treatment, Fluka simulations are being used to design treatment plans in several hadron-therapy centres in Europe.   Fluka calculates the dose distribution for a patient treated at CNAO with proton beams. The colour-bar displays the normalized dose values. Fluka is a Monte Carlo code that very accurately simulates electromagnetic and nuclear interactions in matter. In the 1990s, in collaboration with NASA, the code was developed to predict potential radiation hazards received by space crews during possible future trips to Mars. Over the years, it has become the standard tool to investigate beam-machine interactions, radiation damage and radioprotection issues in the CERN accelerator com...

Spiral phase plates for the generation of high-order Laguerre-Gaussian beams with non-zero radial index

Science.gov (United States)

Ruffato, G.; Carli, M.; Massari, M.; Romanato, F.

2015-03-01

The work of design, fabrication and characterization of spiral phase plates for the generation of Laguerre-Gaussian (LG) beams with non-null radial index is presented. Samples were fabricated by electron beam lithography on polymethylmethacrylate layers over glass substrates. The optical response of these phase optical elements was measured and the purity of the experimental beams was investigated in terms of Laguerre-Gaussian modes contributions. The farfield intensity pattern was compared with theoretical models and numerical simulations, while the expected phase features were confirmed by interferometric analyses. The high quality of the output beams confirms the applicability of these phase plates for the generation of high-order Laguerre-Gaussian beams. A novel application consisting in the design of computer-generated holograms encoding information for light beams carrying phase singularities is shown. A numerical code based on iterative Fourier transform algorithm has been developed for the computation of the phase pattern of phase-only diffractive optical element for illumination under LG beams. Numerical analysis and preliminary experimental results confirm the applicability of these devices as high-security optical elements.

Collective Thomson scattering of a high power electron cyclotron resonance heating beam in LHD

DEFF Research Database (Denmark)

Kubo, S.; Nishiura, M.; Tanaka, K.

2010-01-01

Collective Thomson scattering (CTS) system has been constructed at LHD making use of the high power ECRH system in LHD. The necessary features for CTS, high power probing beams and receiving beams, both with well defined Gaussian profile and with the fine controllability, are endowed in the ECRH ...

Comparison of interradicular distances and cortical bone thickness in Thai patients with class I and class II skeletal patterns using cone-beam computed tomography

Energy Technology Data Exchange (ETDEWEB)

Khumsarn, Nattida [Dental Division of Lamphun Hospital, Lamphun (Thailand); Patanaporn, Virush; Janhom, Apirum; Jotikasthira, Dhirawat [Faculty of Dentistry, Chiang Mai University, Chiang Mai (Thailand)

2016-06-15

This study evaluated and compared interradicular distances and cortical bone thickness in Thai patients with Class I and Class II skeletal patterns, using cone-beam computed tomography (CBCT). Pretreatment CBCT images of 24 Thai orthodontic patients with Class I and Class II skeletal patterns were included in the study. Three measurements were chosen for investigation: the mesiodistal distance between the roots, the width of the buccolingual alveolar process, and buccal cortical bone thickness. All distances were recorded at five different levels from the cementoenamel junction (CEJ). Descriptive statistical analysis and t-tests were performed, with the significance level for all tests set at p<0.05. Patients with a Class II skeletal pattern showed significantly greater maxillary mesiodistal distances (between the first and second premolars) and widths of the buccolingual alveolar process (between the first and second molars) than Class I skeletal pattern patients at 10 mm above the CEJ. The maxillary buccal cortical bone thicknesses between the second premolar and first molar at 8 mm above the CEJ in Class II patients were likewise significantly greater than in Class I patients. Patients with a Class I skeletal pattern showed significantly wider mandibular buccolingual alveolar processes than did Class II patients (between the first and second molars) at 4, 6, and 8 mm below the CEJ. In both the maxilla and mandible, the mesiodistal distances, the width of the buccolingual alveolar process, and buccal cortical bone thickness tended to increase from the CEJ to the apex in both Class I and Class II skeletal patterns.

Comparison of interradicular distances and cortical bone thickness in Thai patients with class I and class II skeletal patterns using cone-beam computed tomography

International Nuclear Information System (INIS)

Khumsarn, Nattida; Patanaporn, Virush; Janhom, Apirum; Jotikasthira, Dhirawat

2016-01-01

This study evaluated and compared interradicular distances and cortical bone thickness in Thai patients with Class I and Class II skeletal patterns, using cone-beam computed tomography (CBCT). Pretreatment CBCT images of 24 Thai orthodontic patients with Class I and Class II skeletal patterns were included in the study. Three measurements were chosen for investigation: the mesiodistal distance between the roots, the width of the buccolingual alveolar process, and buccal cortical bone thickness. All distances were recorded at five different levels from the cementoenamel junction (CEJ). Descriptive statistical analysis and t-tests were performed, with the significance level for all tests set at p<0.05. Patients with a Class II skeletal pattern showed significantly greater maxillary mesiodistal distances (between the first and second premolars) and widths of the buccolingual alveolar process (between the first and second molars) than Class I skeletal pattern patients at 10 mm above the CEJ. The maxillary buccal cortical bone thicknesses between the second premolar and first molar at 8 mm above the CEJ in Class II patients were likewise significantly greater than in Class I patients. Patients with a Class I skeletal pattern showed significantly wider mandibular buccolingual alveolar processes than did Class II patients (between the first and second molars) at 4, 6, and 8 mm below the CEJ. In both the maxilla and mandible, the mesiodistal distances, the width of the buccolingual alveolar process, and buccal cortical bone thickness tended to increase from the CEJ to the apex in both Class I and Class II skeletal patterns

Propagation-invariant vectorial Bessel beams by use of sub wavelength quantized Pancharatnam-Berry phase optics

International Nuclear Information System (INIS)

Niv, A.; Biener, G.; Kleiner, V.; Hasman, E.

2004-01-01

Full Text:Propagation-invariant scalar fields have been extensively studied both theoretically and experimentally, since they were proposed by Durnin et al. These fields were employed in applications such as optical tweezers and for transport and guiding of microspheres. Although there has recently been considerable theoretical interest in propagation-invariant vectorial beams, experimental studies of such beams have remained somewhat limited. One of the most interesting types of propagation-invariant vectorial beam is the linearly polarized axially symmetric beam (LPASB) [l]. Recently, we introduced and experimentally demonstrated propagation-invariant vectorial Bessel beams with linearly polarized axial symmetry based on quantized Pancharatnam-Berry phase optical elements (QPBOEs) [21 and an axicon. QP-BOEs utilize the geometric phase that accompanies space-variant polarization manipulations to achieve a desired phase modification [31. To test our approach we formed QPBOEs with different polarization orders as computer-generated space-variant sub wavelength gratings upon GaAs wafers for use with 10.6 micron laser radiation. The resultant beams were also transmitted through a polarizer that produced a unique propagation-invariant scalar beam. This beam has a propeller-shaped intensity pattern that can be rotated by simple rotation of the polarizer. We therefore have demonstrated the formation of a vectorial Bessel beam by using simple, lightweight thin elements and exploited that beam to perform a controlled rotation of a propeller-shaped intensity pattern that can be suitable for optical tweezers

Determinants of Adult Functional Outcome in Adolescents Receiving Special Educational Assistance

Science.gov (United States)

McGeown, H. R.; Johnstone, E. C.; McKirdy, J.; Owens, D. C.; Stanfield, A. C.

2013-01-01

Background: This study investigates the role of IQ, autistic traits and challenging behaviours in affecting adult outcomes among adolescents who receive special educational assistance. Methods: A total of 58 participants were recruited from an ongoing longitudinal study. All received assessments of IQ, behavioural patterns (using the Childhood…

Generation and application of bessel beams in electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Grillo, Vincenzo, E-mail: vincenzo.grillo@cnr.it [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); CNR-IMEM, Parco Area delle Scienze 37/A, I-43124 Parma (Italy); Harris, Jérémie [Department of Physics, University of Ottawa, 25 Templeton St., Ottawa, Ontario, Canada K1N 6N5 (Canada); Gazzadi, Gian Carlo [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); Balboni, Roberto [CNR-IMM Bologna, Via P. Gobetti 101, 40129 Bologna (Italy); Mafakheri, Erfan [Dipartimento di Fisica Informatica e Matematica, Università di Modena e Reggio Emilia, via G Campi 213/a, I-41125 Modena (Italy); Dennis, Mark R. [H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom); Frabboni, Stefano [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); Dipartimento di Fisica Informatica e Matematica, Università di Modena e Reggio Emilia, via G Campi 213/a, I-41125 Modena (Italy); Boyd, Robert W.; Karimi, Ebrahim [Department of Physics, University of Ottawa, 25 Templeton St., Ottawa, Ontario, Canada K1N 6N5 (Canada)

2016-07-15

We report a systematic treatment of the holographic generation of electron Bessel beams, with a view to applications in electron microscopy. We describe in detail the theory underlying hologram patterning, as well as the actual electron-optical configuration used experimentally. We show that by optimizing our nanofabrication recipe, electron Bessel beams can be generated with relative efficiencies reaching 37±3%. We also demonstrate by tuning various hologram parameters that electron Bessel beams can be produced with many visible rings, making them ideal for interferometric applications, or in more highly localized forms with fewer rings, more suitable for imaging. We describe the settings required to tune beam localization in this way, and explore beam and hologram configurations that allow the convergences and topological charges of electron Bessel beams to be controlled. We also characterize the phase structure of the Bessel beams generated with our technique, using a simulation procedure that accounts for imperfections in the hologram manufacturing process. - Highlights: • Bessel beams with different convergence, topological charge, visible fringes are demonstrated. • The relation between the Fresnel hologram and the probe shape is explained by detailed calculations and experiments. • Among the holograms here presented the highest relative efficiency is 37%, the best result ever reached for blazed holograms.

Generation and application of bessel beams in electron microscopy

International Nuclear Information System (INIS)

Grillo, Vincenzo; Harris, Jérémie; Gazzadi, Gian Carlo; Balboni, Roberto; Mafakheri, Erfan; Dennis, Mark R.; Frabboni, Stefano; Boyd, Robert W.; Karimi, Ebrahim

2016-01-01

We report a systematic treatment of the holographic generation of electron Bessel beams, with a view to applications in electron microscopy. We describe in detail the theory underlying hologram patterning, as well as the actual electron-optical configuration used experimentally. We show that by optimizing our nanofabrication recipe, electron Bessel beams can be generated with relative efficiencies reaching 37±3%. We also demonstrate by tuning various hologram parameters that electron Bessel beams can be produced with many visible rings, making them ideal for interferometric applications, or in more highly localized forms with fewer rings, more suitable for imaging. We describe the settings required to tune beam localization in this way, and explore beam and hologram configurations that allow the convergences and topological charges of electron Bessel beams to be controlled. We also characterize the phase structure of the Bessel beams generated with our technique, using a simulation procedure that accounts for imperfections in the hologram manufacturing process. - Highlights: • Bessel beams with different convergence, topological charge, visible fringes are demonstrated. • The relation between the Fresnel hologram and the probe shape is explained by detailed calculations and experiments. • Among the holograms here presented the highest relative efficiency is 37%, the best result ever reached for blazed holograms.

Flexural Behavior of Corroded Reinforced Recycled Aggregate Concrete Beams

Directory of Open Access Journals (Sweden)

Taoping Ye

2018-01-01

Full Text Available Recycling concrete not only reduces the use of virgin aggregate but also decreases the pressure on landfills. As a result, recycled coarse aggregate (RCA is extensively recommended for new construction projects. However, the flexural behavior of corroded reinforced recycled aggregate concrete (RAC beams is uncertain. The experimental research presented in this paper was performed to investigate the flexural behavior of corroded reinforced RAC beams compared to that of corroded reinforced natural aggregate concrete (NAC beams and consequently explore the possibility of using RAC beams in corrosive environments. Four different percentages of RCA in total mass of coarse aggregate in concrete mixtures (0%, 33%, 66%, and 100% and two different concrete strengths (C30, C60 were the governing parameters. The electrochemical method was adopted to accelerate steel corrosion. Full-scale tests were performed on eight simply supported beams until the failure load was reached. Comparison of load-deflection behavior, crack patterns, failure modes, ductility, and ultimate flexural capacity of corroded reinforced NAC and RAC beams was made based on the experimental results obtained. The comparison results show that the flexural behavior of corroded reinforced RAC beams with an appropriate percentage of RCA is satisfactory compared to the behavior of NAC beams.

Sideband characterization and atmospheric observations with various 340 GHz heterodyne receivers

Energy Technology Data Exchange (ETDEWEB)

Renker, Matthias, E-mail: renker@iap.unibe.ch; Murk, Axel [Institute of Applied Physics, University of Bern, Bern (Switzerland); Rea, Simon P. [STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire (United Kingdom); Emrich, A.; Frisk, U. [OMNISYS Instruments, Västra Frölunda (Sweden)

2014-08-15

This paper describes sideband response measurements and atmospheric observations with a double sideband and two Single Sideband (SSB) receiver prototypes developed for the multi-beam limb sounder instrument stratosphere-troposphere exchange and climate monitor radiometer. We first show an advanced Fourier-Transform Spectroscopy (FTS) method for sideband response and spurious signal characterization. We then present sideband response measurements of the different prototype receivers and we compare the results of the SSB receivers with sideband measurements by injecting a continuous wave signal into the upper and lower sidebands. The receivers were integrated into a total-power radiometer and atmospheric observations were carried out. The observed spectra were compared to forward model spectra to conclude on the sideband characteristics of the different receivers. The two sideband characterization methods show a high degree of agreement for both SSB receivers with various local oscillator settings. The measured sideband response was used to correct the forward model simulations. This improves the agreement with the atmospheric observations and explains spectral features caused by an unbalanced sideband response. The FTS method also allows to quantify the influence of spurious harmonic responses of the receiver.

A symplectic coherent beam-beam model

International Nuclear Information System (INIS)

Furman, M.A.

1989-05-01

We consider a simple one-dimensional model to study the effects of the beam-beam force on the coherent dynamics of colliding beams. The key ingredient is a linearized beam-beam kick. We study only the quadrupole modes, with the dynamical variables being the 2nd-order moments of the canonical variables q, p. Our model is self-consistent in the sense that no higher order moments are generated by the linearized beam-beam kicks, and that the only source of violation of symplecticity is the radiation. We discuss the round beam case only, in which vertical and horizontal quantities are assumed to be equal (though they may be different in the two beams). Depending on the values of the tune and beam intensity, we observe steady states in which otherwise identical bunches have sizes that are equal, or unequal, or periodic, or behave chaotically from turn to turn. Possible implications of luminosity saturation with increasing beam intensity are discussed. Finally, we present some preliminary applications to an asymmetric collider. 8 refs., 8 figs

Laser fusion target illumination optimization with consideration of the beam divergence

International Nuclear Information System (INIS)

Grzanna, J.; Schoennagel, H.

1982-09-01

Using a focusing system with a great focal length it is demonstrated that the radiation divergence considerably influences the illumination optimization. If the channel beam is composed of several single beams, there are two optimum illumination variants: the channel beam tangent and the single beam tangent illumination. Further, it is shown that the illumination channel distribution function can vary in the central region without any effect on the illumination uniformity. The deviation at the periphery is more critical. The most homogeneous illumination and favourable energy transfer would be obtained by low radiation divergence and optimum lateral and axial defocusing of the single beam imaging a suitable near-field intensity pattern on the target surface. It is emphasized that the estimation was made without considering the plasma parameters and the dynamic variation in time. (author)

Beam loss detection system in the arcs of the LHC

Science.gov (United States)

Arauzo, A.; Bovet, C.

2000-11-01

Over the whole circumference of the LHC, Beam Loss Monitors (BLM) will be needed for a continuous surveillance of fast and slow beam losses. In this paper, the location of the BLMs set outside the magnet cryostats in the arcs is proposed. In order to know the number of protons lost on the beam screen, the sensitivity of each BLM has been computed using the program GEANT 3.21, which generates the shower inside the cryostat. The material and the magnetic fields have been described thoroughly in 3-D and the simulation results show the best locations for 6 BLMs needed around each quadrupole. The number of minimum ionizing particles received for each lost proton serves to define local thresholds to dump the beam when the losses are menacing to quench a magnet.

Beam loss detection system in the arcs of the LHC

International Nuclear Information System (INIS)

Arauzo, A.; Bovet, C.

2000-01-01

Over the whole circumference of the LHC, Beam Loss Monitors (BLM) will be needed for a continuous surveillance of fast and slow beam losses. In this paper, the location of the BLMs set outside the magnet cryostats in the arcs is proposed. In order to know the number of protons lost on the beam screen, the sensitivity of each BLM has been computed using the program GEANT 3.21, which generates the shower inside the cryostat. The material and the magnetic fields have been described thoroughly in 3-D and the simulation results show the best locations for 6 BLMs needed around each quadrupole. The number of minimum ionizing particles received for each lost proton serves to define local thresholds to dump the beam when the losses are menacing to quench a magnet

Simulation and Modeling of a Novel Medium Access Control Scheme for Multi-Beam Directional Networking

Science.gov (United States)

2017-03-03

formation of multiple simultaneous beams in both transmit and receive. These multiple beams allows for the re- moval of burdensome coordination...experiments. Rather than hard code all of the underlying pieces for EMANE (such as the over-the-air (OTA) channel, generic routing encapsulation (GRE

Fabrication of nanoscale speckle using broad ion beam milling on polymers for deformation analysis

Directory of Open Access Journals (Sweden)

Qinghua Wang

2016-07-01

Full Text Available We first report a fabrication technique of nanoscale speckle patterns on polymers using broad ion beam milling. The proposed technique is simple and low-cost to produce speckles ranging from dozens of nanometers to less than three micrometers in a large area of several millimeters. Random patterns were successfully produced with an argon (Ar ion beam on the surfaces of four kinds of polymers: the epoxy matrix of carbon fiber reinforced plastic, polyester, polyvinyl formal-acetal, and polyimide. The speckle morphologies slightly vary with different polymers. The fabricated speckle patterns have good time stability and are promising to be used to measure the nanoscale deformations of polymers using the digital image correlation method.

Spatial-phase code-division multiple-access system with multiplexed Fourier holography switching for reconfigurable optical interconnection

Science.gov (United States)

Takasago, Kazuya; Takekawa, Makoto; Shirakawa, Atsushi; Kannari, Fumihiko

2000-05-01

A new, to our knowledge, space-variant optical interconnection system based on a spatial-phase code-division multiple-access technique with multiplexed Fourier holography is described. In this technique a signal beam is spread over wide spatial frequencies by an M -sequence pseudorandom phase code. At a receiver side a selected signal beam is properly decoded, and at the same time its spatial pattern is shaped with a Fourier hologram, which is recorded by light that is encoded with the same M -sequence phase mask as the desired signal beam and by light whose spatial beam pattern is shaped to a signal routing pattern. Using the multiplexed holography, we can simultaneously route multisignal flows into individually specified receiver elements. The routing pattern can also be varied by means of switching the encoding phase code or replacing the hologram. We demonstrated a proof-of-principle experiment with a doubly multiplexed hologram that enables simultaneous routing of two signal beams. Using a numerical model, we showed that the proposed scheme can manage more than 250 routing patterns for one signal flow with one multiplexed hologram at a signal-to-noise ratio of 5.

Inspection of imprint lithography patterns for semiconductor and patterned media

Science.gov (United States)

Resnick, Douglas J.; Haase, Gaddi; Singh, Lovejeet; Curran, David; Schmid, Gerard M.; Luo, Kang; Brooks, Cindy; Selinidis, Kosta; Fretwell, John; Sreenivasan, S. V.

2010-03-01

Imprint lithography has been shown to be an effective technique for replication of nano-scale features. Acceptance of imprint lithography for manufacturing will require demonstration that it can attain defect levels commensurate with the requirements of cost-effective device production. This work summarizes the results of defect inspections of semiconductor masks, wafers and hard disks patterned using Jet and Flash Imprint Lithography (J-FILTM). Inspections were performed with optical and e-beam based automated inspection tools. For the semiconductor market, a test mask was designed which included dense features (with half pitches ranging between 32 nm and 48 nm) containing an extensive array of programmed defects. For this work, both e-beam inspection and optical inspection were used to detect both random defects and the programmed defects. Analytical SEMs were then used to review the defects detected by the inspection. Defect trends over the course of many wafers were observed with another test mask using a KLA-T 2132 optical inspection tool. The primary source of defects over 2000 imprints were particle related. For the hard drive market, it is important to understand the defectivity of both the template and the imprinted disk. This work presents a methodology for automated pattern inspection and defect classification for imprint-patterned media. Candela CS20 and 6120 tools from KLA-Tencor map the optical properties of the disk surface, producing highresolution grayscale images of surface reflectivity, scattered light, phase shift, etc. Defects that have been identified in this manner are further characterized according to the morphology

Dual-beam focused ion beam/electron microscopy processing and metrology of redeposition during ion-surface 3D interactions, from micromachining to self-organized picostructures.

Science.gov (United States)

Moberlychan, Warren J

2009-06-03

Focused ion beam (FIB) tools have become a mainstay for processing and metrology of small structures. In order to expand the understanding of an ion impinging a surface (Sigmund sputtering theory) to our processing of small structures, the significance of 3D boundary conditions must be realized. We consider ion erosion for patterning/lithography, and optimize yields using the angle of incidence and chemical enhancement, but we find that the critical 3D parameters are aspect ratio and redeposition. We consider focused ion beam sputtering for micromachining small holes through membranes, but we find that the critical 3D considerations are implantation and redeposition. We consider ion beam self-assembly of nanostructures, but we find that control of the redeposition by ion and/or electron beams enables the growth of nanostructures and picostructures.

Automated beam placement for breast radiotherapy using a support vector machine based algorithm

International Nuclear Information System (INIS)

Zhao Xuan; Kong, Dewen; Jozsef, Gabor; Chang, Jenghwa; Wong, Edward K.; Formenti, Silvia C.; Wang Yao

2012-01-01

Purpose: To develop an automated beam placement technique for whole breast radiotherapy using tangential beams. We seek to find optimal parameters for tangential beams to cover the whole ipsilateral breast (WB) and minimize the dose to the organs at risk (OARs). Methods: A support vector machine (SVM) based method is proposed to determine the optimal posterior plane of the tangential beams. Relative significances of including/avoiding the volumes of interests are incorporated into the cost function of the SVM. After finding the optimal 3-D plane that separates the whole breast (WB) and the included clinical target volumes (CTVs) from the OARs, the gantry angle, collimator angle, and posterior jaw size of the tangential beams are derived from the separating plane equation. Dosimetric measures of the treatment plans determined by the automated method are compared with those obtained by applying manual beam placement by the physicians. The method can be further extended to use multileaf collimator (MLC) blocking by optimizing posterior MLC positions. Results: The plans for 36 patients (23 prone- and 13 supine-treated) with left breast cancer were analyzed. Our algorithm reduced the volume of the heart that receives >500 cGy dose (V5) from 2.7 to 1.7 cm 3 (p = 0.058) on average and the volume of the ipsilateral lung that receives >1000 cGy dose (V10) from 55.2 to 40.7 cm 3 (p = 0.0013). The dose coverage as measured by volume receiving >95% of the prescription dose (V95%) of the WB without a 5 mm superficial layer decreases by only 0.74% (p = 0.0002) and the V95% for the tumor bed with 1.5 cm margin remains unchanged. Conclusions: This study has demonstrated the feasibility of using a SVM-based algorithm to determine optimal beam placement without a physician's intervention. The proposed method reduced the dose to OARs, especially for supine treated patients, without any relevant degradation of dose homogeneity and coverage in general.

A Real-Time Capable Software-Defined Receiver Using GPU for Adaptive Anti-Jam GPS Sensors

Science.gov (United States)

Seo, Jiwon; Chen, Yu-Hsuan; De Lorenzo, David S.; Lo, Sherman; Enge, Per; Akos, Dennis; Lee, Jiyun

2011-01-01

Due to their weak received signal power, Global Positioning System (GPS) signals are vulnerable to radio frequency interference. Adaptive beam and null steering of the gain pattern of a GPS antenna array can significantly increase the resistance of GPS sensors to signal interference and jamming. Since adaptive array processing requires intensive computational power, beamsteering GPS receivers were usually implemented using hardware such as field-programmable gate arrays (FPGAs). However, a software implementation using general-purpose processors is much more desirable because of its flexibility and cost effectiveness. This paper presents a GPS software-defined radio (SDR) with adaptive beamsteering capability for anti-jam applications. The GPS SDR design is based on an optimized desktop parallel processing architecture using a quad-core Central Processing Unit (CPU) coupled with a new generation Graphics Processing Unit (GPU) having massively parallel processors. This GPS SDR demonstrates sufficient computational capability to support a four-element antenna array and future GPS L5 signal processing in real time. After providing the details of our design and optimization schemes for future GPU-based GPS SDR developments, the jamming resistance of our GPS SDR under synthetic wideband jamming is presented. Since the GPS SDR uses commercial-off-the-shelf hardware and processors, it can be easily adopted in civil GPS applications requiring anti-jam capabilities. PMID:22164116

A Real-Time Capable Software-Defined Receiver Using GPU for Adaptive Anti-Jam GPS Sensors

Directory of Open Access Journals (Sweden)

Dennis Akos

2011-09-01

Full Text Available Due to their weak received signal power, Global Positioning System (GPS signals are vulnerable to radio frequency interference. Adaptive beam and null steering of the gain pattern of a GPS antenna array can significantly increase the resistance of GPS sensors to signal interference and jamming. Since adaptive array processing requires intensive computational power, beamsteering GPS receivers were usually implemented using hardware such as field-programmable gate arrays (FPGAs. However, a software implementation using general-purpose processors is much more desirable because of its flexibility and cost effectiveness. This paper presents a GPS software-defined radio (SDR with adaptive beamsteering capability for anti-jam applications. The GPS SDR design is based on an optimized desktop parallel processing architecture using a quad-core Central Processing Unit (CPU coupled with a new generation Graphics Processing Unit (GPU having massively parallel processors. This GPS SDR demonstrates sufficient computational capability to support a four-element antenna array and future GPS L5 signal processing in real time. After providing the details of our design and optimization schemes for future GPU-based GPS SDR developments, the jamming resistance of our GPS SDR under synthetic wideband jamming is presented. Since the GPS SDR uses commercial-off-the-shelf hardware and processors, it can be easily adopted in civil GPS applications requiring anti-jam capabilities.

Alternative modes for optical trapping and manipulation using counter-propagating shaped beams

International Nuclear Information System (INIS)

Palima, D; Tauro, S; Glückstad, J; Lindballe, T B; Kristensen, M V; Stapelfeldt, H; Keiding, S R

2011-01-01

Counter-propagating beams have enabled the first stable three-dimensional optical trapping of microparticles and this procedure has been enhanced and developed over the years to achieve independent and interactive manipulation of multiple particles. In this work, we analyse counter-propagating shaped-beam traps that depart from the conventional geometry based on symmetric, coaxial counter-propagating beams. We show that projecting shaped beams with separation distances previously considered axially unstable can, in fact, enhance the axial and transverse trapping stiffnesses. We also show that deviating from using perfectly counter-propagating beams to use oblique beams can improve the axial stability of the traps and improve the axial trapping stiffness. These alternative geometries can be particularly useful for handling larger particles. These results hint at a rich potential for light shaping for optical trapping and manipulation using patterned counter-propagating beams, which still remains to be fully tapped

CERN Press Office receives award from Euroscience

CERN Multimedia

2009-01-01

The CERN Communication group has received an award for its efforts in communicating the LHC first beam to the media and the public. James Gillies, head of the Communication group was presented the AlphaGalileo Research Public Relations Award on Wednesday, 14 October during the Euroscience Media Award Ceremony in Hannover. "It’s great to receive this recognition," said Gillies. "Of course, we had great material to work with: the LHC is a fantastic story and one that is going to get even better. Angels, Demons and black holes also had their roles to play, but behind the media interest there’s been a lot of hard work by my team. This is for them." The CERN Communication group also works with communication professionals in all the CERN Member States and major physics labs around the world through the European Particle Physics Communication Network, and the InterAction collaboration. "Without them," says Gillies, &am...

Pollution patterns and underlying relationships of benzophenone-type UV-filters in wastewater treatment plants and their receiving surface water.

Science.gov (United States)

Wu, Ming-Hong; Li, Jian; Xu, Gang; Ma, Luo-Dan; Li, Jia-Jun; Li, Jin-Song; Tang, Liang

2018-05-15

The environmental behaviors of emerging pollutants, benzophenone-type UV filters (BP-UV filters) and their derivatives were investigated in four wastewater treatment plants (WWTPs), and their receiving surface waters in Shanghai. The concentration level of selected BP-UV filters in the WWTPs was detected from ngL -1 to μgL -1 . BP (621-951ngL -1 ) and BP-3 (841-1.32 × 10 3 ngL -1 ) were the most abundant and highest detection frequency individuals among the target BP-UV filters in influents, whereas BP (198-400ngL -1 ), BP-4 (93.3-288ngL -1 ) and BP-3 (146-258ngL -1 ) were predominant in effluents. BP-UV filters cannot be completely removed and the total removal efficiency varied widely (-456% to 100%) during the treatment process. It can be inferred that the usage of BP and BP-3 are higher than other BP-UV filters in the study area. The lowest and highest levels were BP-2 (ND-7.66ngL -1 ) and BP-3 (68.5-5.01 × 10 3 ng L -1 ) in the receiving surface water, respectively. Interestingly, the seasonal variation of BP-3 is larger than those of other BP-UV filters in surface water from Shanghai. There is no obvious pollution pattern of BP-UV filters in the surface water from the cosmetic factory area. The correlation analysis of BP-UV filters between WWTPs effluents and nearby downstream water samples suggested that BP-UV filters emitted from some WWTPs might be the main source of receiving surface water. Preliminary risk assessment indicated that the levels of BP-UV filters detected by the effluent posed medium to high risk to fish as well as other aquatic organisms. Copyright © 2018 Elsevier Inc. All rights reserved.

Slit disk for modified faraday cup diagnostic for determining power density of electron and ion beams

Science.gov (United States)

Teruya, Alan T [Livermore, CA; Elmer,; John, W [Danville, CA; Palmer, Todd A [State College, PA

2011-03-08

A diagnostic system for characterization of an electron beam or an ion beam includes an electrical conducting disk of refractory material having a circumference, a center, and a Faraday cup assembly positioned to receive the electron beam or ion beam. At least one slit in the disk provides diagnostic characterization of the electron beam or ion beam. The at least one slit is located between the circumference and the center of the disk and includes a radial portion that is in radial alignment with the center and a portion that deviates from radial alignment with the center. The electron beam or ion beam is directed onto the disk and translated to the at least one slit wherein the electron beam or ion beam enters the at least one slit for providing diagnostic characterization of the electron beam or ion beam.

Novel Microstrip Patch Antennas with Frequency Agility, Polarization Reconfigurability, Dual Null Steering Capability and Phased Array Antenna with Beam Steering Performance

Science.gov (United States)

Babakhani, Behrouz

Nowadays the wireless communication technology is playing an important role in our daily life. People use wireless devices not only as a conventional communication device but also as tracking and navigation tool, web browsing tool, data storage and transfer tool and so for many other reasons. Based on the user demand, wireless communication engineers try to accommodate as many as possible wireless systems and applications in a single device and therefore, creates a multifunctional device. Antenna, as an integral part of any wireless communication systems, should also be evolved and adjusted with development of wireless transceiver systems. Therefore multifunctional antennas have been introduced to support and enhance the functionality on modern wireless systems. The main focus and contribution of this thesis is design of novel multifunctional microstrip antennas with frequency agility, polarization reconfigurablity, dual null steering capability and phased array antenna with beam steering performance. In this thesis, first, a wide bandwidth(1.10 GHz to 1.60 GHz) right-handed circularly polarized (RHCP) directional antenna for global positioning system (GPS) satellite receive application has been introduced which covers all the GPS bands starting from L1 to L5. This design consists of two crossed bow-tie dipole antennas fed with sequentially phase rotated feed network backed with an artificial high impedance surface (HIS) structure to generate high gain directional radiation patterns. This design shows good CP gain and axial ratio (AR) and wide beamwidth performance. Although this design has good radiation quality, the size and the weight can be reduced as future study. In the second design, a frequency agile antenna was developed which also covers the L-band (L1 to L5) satellite communication frequencies. This frequency agile antenna was designed and realized by new implementation of varactor diodes in the geometry of a circular patch antenna. Beside wide frequency

Implementation of depolarization due to beam-beam effects in the beam-beam interaction simulation tool GUINEA-PIG++

Science.gov (United States)

Rimbault, C.; Le Meur, G.; Blampuy, F.; Bambade, P.; Schulte, D.

2009-12-01

Depolarization is a new feature in the beam-beam simulation tool GUINEA-PIG++ (GP++). The results of this simulation are studied and compared with another beam-beam simulation tool, CAIN, considering different beam parameters for the International Linear Collider (ILC) with a centre-of-mass energy of 500 GeV.

Effect of electron beam on in vitro cultured orchid organs

Energy Technology Data Exchange (ETDEWEB)

Ryu, Jaihyunk; Bae, Seho; Bae, Changhyu [Sunchon National Univ., Suncheon (Korea, Republic of); Kang, Hyun Suk; Lee, Byung Cheol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2010-07-01

Ionizing radiations have been effective mutagen sources to overcome the limitation of the useful genetic resources in natural environment. The study was conducted to investigate an effect of electron beam on organogenesis, growth patterns and genetic variation in the irradiated orchid organs. The in utero cultured rhizomes of orchids were irradiated with the electron beam in the dose range of 15Gy to 2240Gy under the condition of various beam energy and beam current. Significant decreases in survival, growth and organogenesis were observed by increase of intensity of electron beam irradiation. The irradiation intensity of lethal dose 50 of the in utero cultured orchid was estimated as approximately 500Gy to 1000Gy under 10MeV/n, and 1000Gy was optimal for growth and organogenesis of the cultures under 10MeV/n with 0.05mA treatment, and 15Gy {approx} 48Gy under 2MeV/n and 0.5mA electron beam condition. RAPD and ISSR analyses for the electron beam irradiated organs were performed to analyze genetic variation under the electron beam condition. Both of RAPD and ISSR analyses showed higher polymorphic rate in the electron-beam irradiated C. gangrene and C. Kaner.

Beam-plasma instability in ion beam systems used in neutral beam generation

International Nuclear Information System (INIS)

Hooper, E.B. Jr.

1977-02-01

The beam-plasma instability is analyzed for the ion beams used for neutral beam generation. Both positive and negative ion beams are considered. Stability is predicted when the beam velocity is less than the electron thermal velocity; the only exception occurs when the electron density accompanying a negative ion beam is less than the ion density by nearly the ratio of electron to ion masses. For cases in which the beam velocity is greater than the electron thermal velocity, instability is predicted near the electron plasma frequency

Statistical Evaluation of the Azimuth and Elevation Angles Seen at the Output of the Receiving Antenna

Science.gov (United States)

Ziolkowski, Cezary; Kelner, Jan M.

2018-04-01

A method to evaluate the statistical properties of the reception angle seen at the input receiver that considers the receiving antenna pattern is presented. In particular, the impact of the direction and beamwidth of the antenna pattern on distribution of the reception angle is shown on the basis of 3D simulation studies. The obtained results show significant differences between distributions of angle of arrival and angle of reception. This means that the presented new method allows assessing the impact of the receiving antenna pattern on the correlation and spectral characteristics at the receiver input in simulation studies of wireless channel. The use of this method also provides an opportunity for analysis of a co-existence between small cells and wireless backhaul, what is currently a significant problem in designing 5G networks.

Flexural Strength of Carbon Fiber Reinforced Polymer Repaired Cracked Rectangular Hollow Section Steel Beams

Directory of Open Access Journals (Sweden)

Tao Chen

2015-01-01

Full Text Available The flexural behavior of rectangular hollow section (RHS steel beams with initial crack strengthened externally with carbon fiber reinforced polymer (CFRP plates was studied. Eight specimens were tested under three-point loading to failure. The experimental program included three beams as control specimens and five beams strengthened with CFRP plates with or without prestressing. The load deflection curves were graphed and failure patterns were observed. The yield loads and ultimate loads with or without repairing were compared together with the strain distributions of the CFRP plate. It was concluded that yield loads of cracked beams could be enhanced with repairing. Meanwhile, the ultimate loads were increased to some extent. The effect of repair became significant with the increase of the initial crack depth. The failure patterns of the repaired specimens were similar to those of the control ones. Mechanical clamping at the CFRP plate ends was necessary to avoid premature peeling between the CFRP plate and the steel beam. The stress levels in CFRP plates were relatively low during the tests. The use of prestressing could improve the utilization efficiency of CFRP plates. It could be concluded that the patching repair could be used to restore the load bearing capacity of the deficient steel beams.

Image reconstruction from multiple fan-beam projections

International Nuclear Information System (INIS)

Jelinek, J.; Overton, T.R.

1984-01-01

Special-purpose third-generation fan-beam CT systems can be greatly simplified by limiting the number of detectors, but this requires a different mode of data collection to provide a set of projections appropriate to the required spatial resolution in the reconstructed image. Repeated rotation of the source-detector fan, combined with shift of the detector array and perhaps offset of the source with respect to the fan's axis after each 360 0 rotation(cycle), provides a fairly general pattern of projection space filling. The authors' investigated the problem of optimal data-collection geometry for a multiple-rotation fan-beam scanner and of corresponding reconstruction algorithm

Amplification through chaotic synchronization in spatially extended beam-plasma systems

Science.gov (United States)

Moskalenko, Olga I.; Frolov, Nikita S.; Koronovskii, Alexey A.; Hramov, Alexander E.

2017-12-01

In this paper, we have studied the relationship between chaotic synchronization and microwave signal amplification in coupled beam-plasma systems. We have considered a 1D particle-in-cell numerical model of unidirectionally coupled beam-plasma oscillatory media being in the regime of electron pattern formation. We have shown the significant gain of microwave oscillation power in coupled beam-plasma media being in the different regimes of generation. The discovered effect has a close connection with the chaotic synchronization phenomenon, so we have observed that amplification appears after the onset of the complete time scale synchronization regime in the analyzed coupled spatially extended systems. We have also provided the numerical study of physical processes in the chain of beam-plasma systems leading to the chaotic synchronization and the amplification of microwave oscillations power, respectively.

Application of the fractional Fourier transformation to digital holography recorded by an elliptical, astigmatic Gaussian beam.

Science.gov (United States)

Nicolas, F; Coëtmellec, S; Brunel, M; Allano, D; Lebrun, D; Janssen, A J E M

2005-11-01

The authors have studied the diffraction pattern produced by a particle field illuminated by an elliptic and astigmatic Gaussian beam. They demonstrate that the bidimensional fractional Fourier transformation is a mathematically suitable tool to analyse the diffraction pattern generated not only by a collimated plane wave [J. Opt. Soc. Am A 19, 1537 (2002)], but also by an elliptic and astigmatic Gaussian beam when two different fractional orders are considered. Simulations and experimental results are presented.

Optical Interference Coatings Design Contest 2007: triple bandpass filter and nonpolarizing beam splitter.

Science.gov (United States)

Tilsch, Markus; Hendrix, Karen

2008-05-01

A triple bandpass filter (28 solutions received) and a nonpolarizing beam splitter (23 solutions received) were the subjects of the design contest held in conjunction with the 2007 Optical Interference Coatings topical meeting of the Optical Society of America. Fifteen designers participated using a wide spectrum of design approaches and optimization strategies to create the submissions. The results differ significantly, but all meet the contest requirements. Fabien Lemarchand wins both contests by submitting the thinnest (6254 nm) triple bandpass design and the widest (61.7 nm) nonpolarizing beam-splitter design. Michael Trubetskov is in second place, followed by Vladimir Pervak in both contests. The submitted designs are described and evaluated.

Patterned microstructures formed with MeV Au implantation in Si(1 0 0)

International Nuclear Information System (INIS)

Rout, Bibhudutta; Greco, Richard R.; Zachry, Daniel P.; Dymnikov, Alexander D.; Glass, Gary A.

2006-01-01

Energetic (MeV) Au implantation in Si(1 0 0) (n-type) through masked micropatterns has been used to create layers resistant to KOH wet etching. Microscale patterns were produced in PMMA and SU(8) resist coatings on the silicon substrates using P-beam writing and developed. The silicon substrates were subsequently exposed using 1.5 MeV Au 3+ ions with fluences as high as 1 x 10 16 ions/cm 2 and additional patterns were exposed using copper scanning electron microscope calibration grids as masks on the silicon substrates. When wet etched with KOH microstructures were created in the silicon due to the resistance to KOH etching cause by the Au implantation. The process of combining the fabrication of masked patterns with P-beam writing with broad beam Au implantation through the masks can be a promising, cost-effective process for nanostructure engineering with Si

Pattern of failures in gastric cancer patients with lymph node involvement treated by surgery, intraoperative and external beam radiotherapy

International Nuclear Information System (INIS)

Glehen, O.; Peyrat, P.; Beaujard, A.C.; Chapet, O.; Romestaing, P.; Sentenac, I.; Francois, Y.; Vignal, J.; Gerard, J.P.; Gilly, F.N.

2003-01-01

Aims: High local failure rates in gastric cancer have been reported, up to 67%. To achieve a better local control, we evaluated intraoperative radiotherapy (IORT) and external beam radiotherapy (EBRT) in association with surgery for gastric cancer patients with lymph node involvement. We report here the analysis of the patterns of failure for patients involved in this IORT protocol. Material and methods: Forty-two positive lymph node (N+) gastric cancer patients were operated on (31 total, three subtotal and eight extended gastrectomies) with IORT procedure between 1985 and 1997 (33 males, nine females, mean age 61.3 years). IORT was focused on coeliac area (mean dose 15 Gy), followed by EBRT (46 Gy) in 36 patients. Ten patients were pN1 and 32 were pN2. A concurrent systemic chemotherapy (five Fluoro-Uracil and Cisplatinum) was performed in 14 patients. Results: One patient died postoperatively. Actuarial pN+ 10 year survival rate was 44.8%. The 5 year actuarial local control and disease-free survival rates were 78.8 and 47.5%, respectively. As far as patterns of failure were explored, 5 patients have a local coeliac recurrence (12%) and 12 have distant metastases with no evidence of coeliac recurrence. Conclusion: This retrospective analysis suggests a potential effect of IORT and/or EBRT in promoting local control and long-term survival in gastric cancer patients with lymph node involvement

Monitoring the electron beam position at the TESLA test facility free electron laser

Energy Technology Data Exchange (ETDEWEB)

Kamps, T

2000-06-14

The operation of a free electron laser working in the Self Amplified Spontaneous Emission mode (SASE FEL) requires the electron trajectory to be aligned with very high precision in overlap with the photon beam. In order to ensure this overlap, one module of the SASE FEL undulator at the TESLA Test Facility (TTF) is equipped with a new type of waveguide beam position monitor (BPM). Four waveguides are arranged symmetrically around the beam pipe, each channel couples through a small slot to the electromagnetic beam field. The induced signal depends on the beam intensity and on the transverse beam position in terms of beam-to-slot distance. With four slot--waveguide combinations a linear position sensitive signal can be achieved, which is independent of the beam intensity. The signals transduced by the slots are transferred by ridged waveguides through an impedance matching stage into a narrowband receiver tuned to 12 GHz. The present thesis describes design, tests, and implementation of this new type of BPM. (orig.)

Interference-aware random beam selection schemes for spectrum sharing systems

KAUST Repository

Abdallah, Mohamed; Qaraqe, Khalid; Alouini, Mohamed-Slim

2012-01-01

users. In this work, we develop interference-aware random beam selection schemes that provide enhanced performance for the secondary network under the condition that the interference observed by the receivers of the primary network is below a

Measurements of gas velocity in supersonic flow using a laser beam

International Nuclear Information System (INIS)

Airoldi, V.J.T.; Santos, R. dos

1982-01-01

A study of measurements of supersonic velocities in a wind tunnel using a laser beam was performed. Techniques using lasers are most suitable because they do not disturb the gas flow. This work presents the technique entitled as fringe technique. It works using interference patterns due to two perpendicular laser beams crossing the sample (i.e. the gas flow). Experimental results are compared with other usual techniques. (R.S.)

Ionic molecular films. Applications. 3. Electron beam stimulated enhanced adherence

Energy Technology Data Exchange (ETDEWEB)

Baldacchini, G; Montereali, R M; Scavarda do Carmo, L C

1989-11-01

This paper reports on the advantages of the use of the technique of electron beam lithography to imprint enhanced sensitive patterns on ionic molecular substrates (bulk crystals or films). With this technique, localized superficial defects are produced which change the chemical properties of surfaces. Sensitized surfaces react with absorbates providing enhanced adherence of such substances. The use of spacially controlled electron beams allows the construction of small (sub-micron) feature chemical and very localized enhanced adherence of absorbates.

Commissioning and operational scenarios of the LHC beam loss monitor system

International Nuclear Information System (INIS)

Holzer, E.B.

2007-01-01

One of the most critical elements for the protection of CERN's Large Hadron Collider (LHC) is its beam loss monitoring (BLM) system. It must prevent quenches in the super conducting magnets and damage of machine components due to beam losses. The contribution will discuss the commissioning procedures of the BLM system and envisaged operational scenarios. About 4000 monitors will be installed around the ring. When the loss rate exceeds a predefined threshold value, a beam abort is requested. Magnet quench and damage levels vary as a function of beam energy and loss duration. Consequently, the beam abort threshold values vary accordingly. By measuring the loss pattern, the BLM system helps to identify the loss mechanism. Furthermore, it will be an important tool for commissioning, machine setup and studies. Special monitors will be used for the setup and control of the collimators. (author)

Beam Techniques - Beam Control and Manipulation

International Nuclear Information System (INIS)

Minty, Michiko G

2003-01-01

We describe commonly used strategies for the control of charged particle beams and the manipulation of their properties. Emphasis is placed on relativistic beams in linear accelerators and storage rings. After a brief review of linear optics, we discuss basic and advanced beam control techniques, such as transverse and longitudinal lattice diagnostics, matching, orbit correction and steering, beam-based alignment, and linac emittance preservation. A variety of methods for the manipulation of particle beam properties are also presented, for instance, bunch length and energy compression, bunch rotation, changes to the damping partition number, and beam collimation. The different procedures are illustrated by examples from various accelerators. Special topics include injection and extraction methods, beam cooling, spin transport and polarization

Beam Techniques - Beam Control and Manipulation

Energy Technology Data Exchange (ETDEWEB)

Minty, Michiko G

2003-04-24

We describe commonly used strategies for the control of charged particle beams and the manipulation of their properties. Emphasis is placed on relativistic beams in linear accelerators and storage rings. After a brief review of linear optics, we discuss basic and advanced beam control techniques, such as transverse and longitudinal lattice diagnostics, matching, orbit correction and steering, beam-based alignment, and linac emittance preservation. A variety of methods for the manipulation of particle beam properties are also presented, for instance, bunch length and energy compression, bunch rotation, changes to the damping partition number, and beam collimation. The different procedures are illustrated by examples from various accelerators. Special topics include injection and extraction methods, beam cooling, spin transport and polarization.

Applications of power beaming from space-based nuclear power stations

International Nuclear Information System (INIS)

Powell, J.R.; Botts, T.E.; Hertzberg, A.

1981-01-01

Power beaming from space-based reactor systems is examined using an advanced compact, lightweight Rotating Bed Reactor (RBR). Closed Brayton power conversion efficiencies in the range of 30 to 40% can be achieved with turbines, with reactor exit temperatures on the order of 2000 0 K and a liquid drop radiator to reject heat at temperatures of approx. 500 0 K. Higher RBR coolant temperatures (up to approx. 3000 0 K) are possible, but gains in power conversion efficiency are minimal, due to lower expander efficiency (e.g., a MHD generator). Two power beaming applications are examined - laser beaming to airplanes and microwave beaming to fixed ground receivers. Use of the RBR greatly reduces system weight and cost, as compared to solar power sources. Payback times are a few years at present prices for power and airplane fuel

Beam-beam studies for FCC-hh

CERN Document Server

AUTHOR|(CDS)2068329; Pieloni, Tatiana; Buffat, Xavier; Furuseth, Sondre Vik

2017-01-01

The Future Circular Collider hadron-hadron (FCC-hh) design study is currently exploring different IR design possibilities including round and flat optics or different crossing schemes. The present study intends to evaluate each scenario from the beam-beam effects point of view. In particular the single particle long term stability to maximize beam lifetimes and luminosity reach is used to quantify the differences. The impact of strong head on interactions on the beam quality and lifetime is addressed by means of GPU accelerated simulations code featuring a weak-strong 6-dimensional beam-beam interaction.

PREVAIL: IBM's e-beam technology for next generation lithography

Science.gov (United States)

Pfeiffer, Hans C.

2000-07-01

PREVAIL - Projection Reduction Exposure with Variable Axis Immersion Lenses represents the high throughput e-beam projection approach to NGL which IBM is pursuing in cooperation with Nikon Corporation as alliance partner. This paper discusses the challenges and accomplishments of the PREVAIL project. The supreme challenge facing all e-beam lithography approaches has been and still is throughput. Since the throughput of e-beam projection systems is severely limited by the available optical field size, the key to success is the ability to overcome this limitation. The PREVAIL technique overcomes field-limiting off-axis aberrations through the use of variable axis lenses, which electronically shift the optical axis simultaneously with the deflected beam so that the beam effectively remains on axis. The resist images obtained with the Proof-of-Concept (POC) system demonstrate that PREVAIL effectively eliminates off- axis aberrations affecting both resolution and placement accuracy of pixels. As part of the POC system a high emittance gun has been developed to provide uniform illumination of the patterned subfield and to fill the large numerical aperture projection optics designed to significantly reduce beam blur caused by Coulomb interaction.

Dynamical chaos and beam-beam models

International Nuclear Information System (INIS)

Izrailev, F.M.

1990-01-01

Some aspects of the nonlinear dynamics of beam-beam interaction for simple one-dimensional and two-dimensional models of round and flat beams are discussed. The main attention is paid to the stochasticity threshold due to the overlapping of nonlinear resonances. The peculiarities of a round beam are investigated in view of using the round beams in storage rings to get high luminosity. 16 refs.; 7 figs

Beam, multi-beam and broad beam production with COMIC devices