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Review of Scientific Instruments

John F Seely, Lawrence T Hudson, Albert Henins, Uri Feldman
An x-ray spectrometer employing a thin (50 μm) silicon transmission crystal was used to record high-resolution Cu Kα spectra from a laboratory x-ray source. The diffraction was from the (331) planes that were at an angle of 13.26° to the crystal surface. The components of the spectral lines resulting from single-vacancy (1s) and double-vacancy (1s and 3d) transitions were observed. After accounting for the natural lifetime widths from reference double-crystal spectra and the spatial resolution of the image plate detector, the intrinsic broadening of the transmission crystal was measured to be as small as 0...
October 2017: Review of Scientific Instruments
F Caporaletti, A I Chumakov, R Rüffer, G Monaco
Time-domain interferometry (TDI) based on nuclear resonant scattering of synchrotron radiation by Mössbauer nuclei is a promising technique to study slow dynamics at the interatomic length scale. In order to improve the efficiency of this technique, a new TDI scheme is developed involving the use of a nuclear absorber with a two-line energy spectrum combined with a single-line spectrum. Different from other TDI setups, the issue of external vibrations is much reduced since the two absorbers are at rest and no velocity transducer is used...
October 2017: Review of Scientific Instruments
Xiuyuan Chen, Xiyuan Peng, Ran Duan, Junbao Li
With the development of deep learning, research on image target recognition has made great progress in recent years. Remote sensing detection urgently requires target recognition for military, geographic, and other scientific research. This paper aims to solve the synthetic aperture radar image target recognition problem by combining deep and kernel learning. The model, which has a multilayer multiple kernel structure, is optimized layer by layer with the parameters of Support Vector Machine and a gradient descent algorithm...
October 2017: Review of Scientific Instruments
Young-Min Shin, Michael Figora
A stable femtosecond electron beam system has been configured for time-resolved pump-probe experiments. The ultrafast electron diffraction (UED) system is designed with a sub-MeV photoelectron beam source pulsed by a femtosecond UV laser and nondispersive beamline components, including a bunch compressor-a pulsed S-band klystron is installed and fully commissioned with 5.5 MW peak power in a 2.5 μs pulse length. A single-cell RF photo-gun is designed to produce 1.6-16 pC electron bunches in a photoemission mode with 150 fs pulse duration at 0...
October 2017: Review of Scientific Instruments
G Wang, W A Peebles, E J Doyle, N A Crocker, C Wannberg, C Lau, G R Hanson, J L Doane
The present design concept for the ITER low-field-side reflectometer transmission line (TL) consists of an ∼40 m long, 6.35 cm diameter helically corrugated waveguide (WG) together with ten 90° miter bends. This paper presents an evaluation of the TL performance at low frequencies (33-50 GHz) where the predicted HE11 mode ohmic and mode conversion losses start to increase significantly. Quasi-optical techniques were used to form a near Gaussian beam to efficiently couple radiation in this frequency range into the WG...
October 2017: Review of Scientific Instruments
Chaoyong Chen, Shaoping Shi, Yaohui Zheng
In an actual setup of squeezed state generation, the stability of a squeezing factor is mainly limited by the performance of the servo-control system, which is mainly influenced by the shot noise and gain of a photodetector. We present a unique transformer-coupled LC resonant amplifier as a photodetector circuit to reduce the electronic noise and increase the gain of the photodetector. As a result, we obtain a low-noise, high gain photodetector with the gain of more than 1.8×10(5) V/A, and the input current noise of less than 4...
October 2017: Review of Scientific Instruments
Wu Ouyang, Zhiming Zhao, Le Cai, Xiaoyang Yuan
A measurement system error is a key factor that disturbs the identification precision of sliding bearing's dynamic characteristic coefficients. The transfer process and influence rule of errors from a measurement system to dynamic characteristic coefficients are analyzed by solving the dynamic characteristic measurement model. In order to ensure that the identification errors are no more than 40%, the amplitude error and phase error of the transfer function of the measurement system should be controlled within 10% and 1°, respectively...
October 2017: Review of Scientific Instruments
Felicity McGrath, Allan S Johnson, Dane R Austin, Peter Hawkins, David Wood, Lukas Miseikis, Emma R Simpson, Marta Castillejo, Ricardo Torres, Susan Parker, Thomas Siegel, Jon P Marangos
We present an apparatus for performing gas phase high-harmonic generation spectroscopy of molecules primarily found in the liquid phase. Liquid molecular samples are heated in a temperature controlled bath and their vapour is used to back a continuous flow gas jet, with vapour pressures of over 1 bar possible. In order to demonstrate the system, we perform high harmonic spectroscopy experiments in benzene with a 1.8 μm driving field. Using the unique capabilities of the system, we obtain spectra that are nearly free from the effects of longitudinal phase-matching, amenable to comparison with advanced numerical modelling...
October 2017: Review of Scientific Instruments
J L Niedziela, R Mills, M J Loguillo, H D Skorpenske, D Armitage, H L Smith, J Y Y Lin, M S Lucas, M B Stone, D L Abernathy
We present the design and operating characteristics of a vacuum furnace used for inelastic neutron scattering experiments on a time-of-flight chopper spectrometer. The device is an actively water cooled radiant heating furnace capable of performing experiments up to 1873 K. Inelastic neutron scattering studies performed with this furnace include studies of phonon dynamics and metallic liquids. We describe the design, control, characterization, and limitations of the equipment. Further, we provide comparisons of the neutron performance of our device with commercially available options...
October 2017: Review of Scientific Instruments
Nicola V Y Scarlett, Damien Hewish, Rachel Pattel, Nathan A S Webster
This paper describes the development and testing of a novel capillary flow cell for use in in situ powder X-ray diffraction experiments. It is designed such that it achieves 200° of rotation of the capillary whilst still allowing the flow of gas through the sample and the monitoring of off gas via mass spectrometry, gas chromatography, or other such analytical techniques. This high degree of rotation provides more uniform heating of the sample than can be achieved in static cells or those with lower rotational ranges and consequently also improves particle statistics...
October 2017: Review of Scientific Instruments
Dong Liu, Weihai Chen, Zhongcai Pei, Jianhua Wang
Brain-computer interfaces have been a novel approach to translate human intentions into movement commands in robotic systems. This paper describes an electroencephalogram-based brain-controlled lower-limb exoskeleton for gait training, as a proof of concept towards rehabilitation with human-in-the-loop. Instead of using conventional single electroencephalography correlates, e.g., evoked P300 or spontaneous motor imagery, we propose a novel framework integrated two asynchronous signal modalities, i.e., sensorimotor rhythms (SMRs) and movement-related cortical potentials (MRCPs)...
October 2017: Review of Scientific Instruments
P Angland, D Haberberger, S T Ivancic, D H Froula
Angular filter refractometry (AFR) is a novel technique used to characterize the density profiles of laser-produced, long-scale-length plasmas [Haberberger et al., Phys. Plasmas 21, 056304 (2014)]. A new method of analysis for AFR images was developed using an annealing algorithm to iteratively converge upon a solution. A synthetic AFR image is constructed by a user-defined density profile described by eight parameters, and the algorithm systematically alters the parameters until the comparison is optimized...
October 2017: Review of Scientific Instruments
Jeffrey J Richards, Norman J Wagner, Paul D Butler
In situ measurements are an increasingly important tool to inform the complex relationship between nanoscale properties and macroscopic material measurements. Knowledge of these phenomena can be used to develop new materials to meet the performance demands of next generation technologies. Conductive complex fluids have emerged as an area of research where the electrical and mechanical properties are key design parameters. To study the relationship between microstructure, conductivity, and rheology, we have developed a small angle neutron scattering (SANS) compatible Couette rheological geometry capable of making impedance spectroscopy measurements under continuous shear...
October 2017: Review of Scientific Instruments
Sichao Hou, Ruiqing Huo, Ming Su
Commonly used thermal analysis tools such as calorimeter and thermal conductivity meter are separated instruments and limited by low throughput, where only one sample is examined each time. This work reports an infrared based optical calorimetry with its theoretical foundation, which is able to provide an integrated solution to characterize thermal properties of materials with high throughput. By taking time domain temperature information of spatially distributed samples, this method allows a single device (infrared camera) to determine the thermal properties of both phase change systems (melting temperature and latent heat of fusion) and non-phase change systems (thermal conductivity and heat capacity)...
October 2017: Review of Scientific Instruments
O Sanni, O Bukuaghangin, M Huggan, N Kapur, T Charpentier, A Neville
There is a considerable interest to investigate surface crystallization in order to have a full mechanistic understanding of how layers of sparingly soluble salts (scale) build on component surfaces. Despite much recent attention, a suitable methodology to improve on the understanding of the precipitation/deposition systems to enable the construction of an accurate surface deposition kinetic model is still needed. In this work, an experimental flow rig and associated methodology to study mineral scale deposition is developed...
October 2017: Review of Scientific Instruments
Bin Sheng, Guohua Chen, Yuanshen Huang, Luwen Luo
Based on the Littrow and Littman configurations for autocollimation, two methods are proposed herein with a fore-end light path comprising fused fiber couplers and fiber port collimators to measure the diffraction grating period. The experimental data from a uniform-line-spacing grating with a nominal value of 1200 lines/mm agreed well with theoretical values and with measurement errors of the Littrow and the Littman configurations of 1.05 × 10(-4) and 4.99 × 10(-5), respectively. Both methods were demonstrated to reduce the diameter of the laser spot and improve the alignment precision of the measurement system...
October 2017: Review of Scientific Instruments
B R Johnson, F Columbro, D Araujo, M Limon, B Smiley, G Jones, B Reichborn-Kjennerud, A Miller, S Gupta
In this paper, we present the design and measured performance of a novel cryogenic motor based on a superconducting magnetic bearing (SMB). The motor is tailored for use in millimeter-wave half-wave plate (HWP) polarimeters, where a HWP is rapidly rotated in front of a polarization analyzer or polarization-sensitive detector. This polarimetry technique is commonly used in cosmic microwave background polarization studies. The SMB we use is composed of fourteen yttrium barium copper oxide (YBCO) disks and a contiguous neodymium iron boron (NdFeB) ring magnet...
October 2017: Review of Scientific Instruments
Eiichirou Kawamori, Jinting Chen, Chiahsuan Lin, Zongmau Lee
Ring-averaged velocity distribution function of ions at a fixed guiding center position is a fundamental quantity in the gyrokinetic plasma physics. We have developed a diagnostic tool for the ring averaged velocity distribution function of ions for laboratory plasma experiments, which is named as the ring-averaged ion distribution function probe (RIDFP). The RIDFP is a set of ion collectors for different velocities. It is designed to be immersed in magnetized plasmas and achieves momentum selection of incoming ions by the selection of the ion Larmor radii...
October 2017: Review of Scientific Instruments
Pengzhan Liu, Junhui Hu
In this paper, a removal method of micro/nanoscale particles in a submillimeter-diameter area at the interface between an aqueous suspension droplet and silicon substrate surface around a selectable point is proposed and demonstrated. It employs the acoustic streaming generated by an ultrasonically vibrating micro manipulating probe (MMP). The operating frequency of the device is 124.5 kHz, at which the micro manipulating probe oscillates approximately linearly. The experiments show that microscale particles with a diameter of 3-5 μm and nanoscale particles with a diameter of 300-500 nm in submillimeter-diameter areas can be removed in about 1...
October 2017: Review of Scientific Instruments
Weijie Zhang, Yuhang Chen, Jiaru Chu
To enhance the harmonic signals in intermittent contact atomic force microscopy, we proposed the double-hole structural modification. Finite element analyses and experiments demonstrated the capability and advantages of the developed method. An infinite set of harmonic cantilevers can be optimized by proper selections of hole size, position, and inter-distance. The second and third resonance frequencies are simultaneously regulated to be integer multiples of the fundamental frequency. In the meanwhile, the alteration of cantilever stiffness is kept minimum...
October 2017: Review of Scientific Instruments
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