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Feb 1988

Volume 59, Issue 2, pp. 217-393

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Auger electron spectroscopy: Method for the accurate measurement of signal and noise and a figure of merit for the performance of AES instrument sensitivity

M. P. Seah and C. P. Hunt

Rev. Sci. Instrum. 59, 217 (1988); http://dx.doi.org/10.1063/1.1140230 (11 pages) | Cited 6 times

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The absolute signal and absolute noise behaviors of Auger electron spectrometers are analyzed for the pulse counting, analog amplification, beam blanking, and sinusoidally modulated differential modes. Measurements for a Varian 10‐keV CMA system and a VG Scientific Microlab support the theoretical predictions in detail. Measurements using a 5‐keV electron beam at 45° angle of incidence allow a figure of merit factor F to be derived such that the defined signal‐to‐noise ratio for the Cu L3M45M45 intense peak is given by F(It)0.5, where I is the beam current ( μA) and t is either the period averaging time or twice the exponential time constant (ms). It is shown that the F value using pulse counting is 20.5 times that using current amplification, 2 times that using beam blanking, and 3.3 times that using modulated differentiation. The F value, under specified conditions, allows a very broad characterization of the instrument’s sensitivity. The measured F values for the above instruments are all very similar and are equivalent to a value of 40 in the pulse counting mode.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers
79.20.Fv Electron impact: Auger emission
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Scanning positron microbeam

G. R. Brandes, K. F. Canter, T. N. Horsky, P. H. Lippel, and A. P. Mills

Rev. Sci. Instrum. 59, 228 (1988); http://dx.doi.org/10.1063/1.1140231 (5 pages) | Cited 20 times

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The construction and operation of a scanning positron microbeam is reported. The positrons are obtained from a doubly remoderated positron beam with a normalized brightness‐per‐volt of 1.8×105 e+ s−1 cm−2 rad−2 V−1 Ci−1. The beam of 8000 e+ s−1 is brought to a 10×50 μm2 focus by a sectored lens and is scanned across a test grid. Possible applications to defect spectroscopy and the observation of small samples will be discussed.
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78.70.Bj Positron annihilation
71.20.-b Electron density of states and band structure of crystalline solids
71.60.+z Positron states
36.10.Dr Positronium

Modified operation of the seven‐element electrostatic Chutjian–Kuyatt lens system

L. Boesten

Rev. Sci. Instrum. 59, 233 (1988); http://dx.doi.org/10.1063/1.1140232 (5 pages) | Cited 8 times

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We reconsider the properties of the seven‐element electrostatic zoom‐lens system of Chutjian and Kuyatt [Rev. Sci. Instrum. 50, 347 (1979)] from our experience with a ‘‘visual’’ beam‐tracing program, and propose a modified operation of this lens system to achieve simultaneously correct focusing, zero beam angle, and constant target size over the zoom range. Rational function fits to all driving voltages are given. A ray‐tracing program for a personal computer is described in the Appendix.
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41.20.Cv Electrostatics; Poisson and Laplace equations, boundary-value problems
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems

Resonance enhancement of optoacoustic signal for frequency stabilization of CO2 laser pump for CH3OH FIR laser

J. R. Fishback, M. Azar, C. A. Ventrice, and D. P. Hutchinson

Rev. Sci. Instrum. 59, 238 (1988); http://dx.doi.org/10.1063/1.1140233 (4 pages) | Cited 2 times

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The resonance enhancement of an optoacoustic signal, generated in methyl alcohol vapor, is investigated with the objective of obtaining a reliable discriminator at reduced pump power levels. The 9P(36) pump line from a CO2 laser is used throughout the study. The optoacoustic signal strength and resonator Q are measured at the fundamental longitudinal resonant frequency for various resonator geometries and vapor pressures. Resonators of length ranging from 12 to 24 cm are examined for tubes of inner diameter 7.5, 9.5, and 10.6 mm. The maximum vapor pressure for which a reliable discriminator is obtained is found to be 1 Torr. Both the optacoustic signal strength and the resonator Q increase with increasing vapor pressure and decreasing resonator length. The highest Q is obtained for the 10.6‐mm‐i.d. tubes. Using a resonator of the length 14 cm and 10.6‐mm i.d. at a vapor pressure of 1 Torr, it is found that a pump power as low as 0.4 W gives a reliable discriminator.
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42.60.Fc Modulation, tuning, and mode locking
42.55.Lt Gas lasers including excimer and metal-vapor lasers
42.55.-f Lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Fourier transform, electromodulated, infrared spectrometer for studies at the electrochemical interface

F. Ozanam and J‐N. Chazalviel

Rev. Sci. Instrum. 59, 242 (1988); http://dx.doi.org/10.1063/1.1140234 (7 pages) | Cited 14 times

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We report on a newly built infrared spectrometer to be used for vibrational studies at the electrochemical interface. The usual way to select the weak interface absorption consists in changing the electrode potential and measuring the associated change in absorption. However, up to now it was difficult to benefit from both the advantages of using a lock‐in detection and Fourier transform spectroscopy. Our apparatus allows simultaneous use of these two techniques. This is achieved by using a slow scan speed (∼6 μm s−1) for the Michelson interferometer. The electrode potential may be modulated at a frequency as low as 100 Hz. The ultimate sensitivity of our apparatus corresponds to a relative change of transmitted light intensity of ΔI/I∼10−6, for a measuring time of 45 min, in the 800–4200 cm−1 range, with a resolution of 25 cm−1. Our ultimate resolution capability is 0.5 cm−1. Data are presented that have been obtained on the n‐Si/acetonitrile interface using an attenuated total reflection geometry, which allows further improvement of the performances by one order of magnitude.
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07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
07.60.Ly Interferometers
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

500 °C infrared absorption cell

A. M. Robinson, M. Billing, and D. Garand

Rev. Sci. Instrum. 59, 249 (1988); http://dx.doi.org/10.1063/1.1140235 (3 pages) | Cited 1 time

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A high‐temperature IR‐transmitting absorption cell has been designed and tested. The cell is heated by utilizing the cell wall as the heating element. A PTFE (Teflon) gasket double‐window assembly allows temperatures as high as 500 °C to be attained. Temperature uniformity of 4 °C is observed, and preliminary absorption results by CO2 at 10 μm are presented.
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06.60.Ei Sample preparation (including design of sample holders)
07.30.Kf Vacuum chambers, auxiliary apparatus, and materials
07.10.-h Mechanical instruments and equipment
07.77.-n Atomic, molecular, and charged-particle sources and detectors
37.20.+j Atomic and molecular beam sources and techniques

Current response characteristics of microchannel plates x‐ray detector using synchrotron radiation (0.6–2 keV and 5–20 keV)

T. Kondoh, N. Yamaguchi, T. Cho, M. Hirata, S. Miyoshi, S. Aoki, H. Maezawa, and M. Nomura

Rev. Sci. Instrum. 59, 252 (1988); http://dx.doi.org/10.1063/1.1140236 (4 pages) | Cited 13 times

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The characteristics of microchannel plates (MCPs) for detection of x rays have been investigated using synchrotron radiation in the energy ranges from 0.6 to 2.0 keV and from 5 to 20 keV. Microchannel plates are operated under the condition of an unsaturated pulse‐height distribution mode. The current response curve of MCPs is measured continuously with x‐ray energy variation for the first time. The experimental result of some discontinuous jumps in the response is obtained at the energies corresponding to the absorption edge of the MCP materials. In the low‐energy range (hν<2 keV), the dependence of the current response to the incident angle of x rays to the channel axis θ is measured to be proportional to cot θ, which is interpreted by the x‐ray absorption near the surface of MCP channel wall. While, in the high‐energy range (hν>5 keV), a weak dependence on θ is observed, and is attributed mainly to the penetration of x rays through multiple channels.
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07.85.-m X- and γ-ray instruments
52.70.La X-ray and γ-ray measurements

Fluorescence referencing for fiber‐optic thermometers using visible wavelengths

K. T. V. Grattan, R. K. Selli, and A. W. Palmer

Rev. Sci. Instrum. 59, 256 (1988); http://dx.doi.org/10.1063/1.1140275 (4 pages) | Cited 2 times

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A fiber‐optic temperature sensor, operating on the principle of differential absorption effects with temperature, has been constructed using visible wavelength sensing and a ruby fluorescence‐based internally generated reference scheme. Results of an investigation of the system and a comparison with previous work by the authors on a related system are reported.
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42.81.Pa Sensors, gyros
07.20.Dt Thermometers

Use of quartz‐halogen lamps as the reference source for spectroradiometric temperature measurements

Phillip H. Paul and Sidney A. Self

Rev. Sci. Instrum. 59, 260 (1988); http://dx.doi.org/10.1063/1.1140237 (5 pages) | Cited 1 time

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Spectroradiometric temperature measurement techniques require a stable high‐temperature reference source. It is essential that the brightness temperature of this reference source be calibrated against an accepted standard. We show that the optimal choice for the operating temperature of the reference source is slightly higher than the medium under test. We consider the use of miniature quartz‐halogen lamps, as an alternative to the traditional tungsten ribbon lamp, as the reference source for emission–absorption pyrometry. The use of subminiature quartz‐halogen lamps can extend the optimum operating condition by over 500 K and are less prone to lamp envelope fouling than tungsten vacuum lamps.
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42.72.-g Optical sources and standards
07.20.Ka High-temperature instrumentation; pyrometers

Design aspects of a modular instrumentation system for thermal diagnostic studies

Wayne A. Rubey and Richard A. Grant

Rev. Sci. Instrum. 59, 265 (1988); http://dx.doi.org/10.1063/1.1140238 (5 pages) | Cited 18 times

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A laboratory instrumentation system has been developed which provides flexibility for conducting an extensive range of thermal investigations of organic materials. Test samples can be of gaseous, liquid, solid, polymeric, composite, or even multiphase nature. This modular system uses an interchangeable test‐cell assembly concept for performing laboratory experiments and physical simulations. Incorporated in‐line instrumental analysis techniques provide sensitive and comprehensive effluent analyses of the thermal‐related degradation behavior.
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07.20.Ka High-temperature instrumentation; pyrometers
81.70.-q Methods of materials testing and analysis
65.20.-w Thermal properties of liquids
65.40.gd Entropy

Emissive probe current bias method of measuring dc vacuum potential

D. Diebold, N. Hershkowitz, A. D. Bailey, M. H. Cho, and T. Intrator

Rev. Sci. Instrum. 59, 270 (1988); http://dx.doi.org/10.1063/1.1140239 (6 pages) | Cited 28 times

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It is experimentally demonstrated that, with proper current bias, emissive probes can accurately measure dc electric potential in a vacuum. A comparison is made of the accuracy and time response of this ‘‘vacuum current bias’’ method with two other emissive probe techniques, the inflection point in the limit of zero emission, and the floating potential of a strongly heated probe.
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07.50.-e Electrical and electronic instruments and components
52.70.Ds Electric and magnetic measurements

Automated outgassing facility with inductive heating

J. E. Simpkins and P. K. Mioduszewski

Rev. Sci. Instrum. 59, 276 (1988); http://dx.doi.org/10.1063/1.1140240 (4 pages) | Cited 3 times

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The use of graphite for both first walls and limiters in fusion experiments has increased during recent years. However, graphite contains large amounts of gaseous contaminants that affect the plasma adversely. To study the vacuum characteristics of various candidate graphites and to evaluate conditioning techniques for these materials, we have built an outgassing facility, which is described in this paper. Induction heating is used to heat the sample to 2000 °C. This heating technique was chosen to avoid heating other components in the vacuum chamber. Since the walls are heated by radiation from the sample at the higher temperatures, they are kept at a constant elevated temperature of 100 °C by thermostatically controlled heaters throughout the experiment. The entire system is automated. Some results that compare POCO and pyrolytic graphites are shown.
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07.20.Ka High-temperature instrumentation; pyrometers
65.20.-w Thermal properties of liquids
65.40.gd Entropy
28.52.-s Fusion reactors

Stability boundaries and phase‐space measurement for spatially extended dynamical systems

F. Simonelli and J. P. Gollub

Rev. Sci. Instrum. 59, 280 (1988); http://dx.doi.org/10.1063/1.1140241 (5 pages) | Cited 5 times

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Automated methods of studying the stability boundaries and phase‐space dynamics of a spatially extended dynamical system are presented. The stability boundaries are determined accurately as a function of external parameters in an automated search. The amplitudes of the individual spatial modes are measured in real time in order to determine the structure of the attractors in phase space. Some control over initial conditions allows the basins of attraction and the transients leading to the attractors to be studied as well. The methods are applied specifically to interacting waves on a fluid surface, but should also be useful to other extended dynamical systems.
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05.45.-a Nonlinear dynamics and chaos
47.10.-g General theory in fluid dynamics
47.80.-v Instrumentation and measurement methods in fluid dynamics
45.05.+x General theory of classical mechanics of discrete systems

Novel approach for particle velocity and size measurement under plasma conditions

Tadahiro Sakuta and Maher I. Boulos

Rev. Sci. Instrum. 59, 285 (1988); http://dx.doi.org/10.1063/1.1140242 (7 pages) | Cited 12 times

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A novel technique is proposed for the simultaneous, in‐flight, measurement of the velocity and size of individual particles under plasma conditions. The method is based on the observation of each particle through its own emission and the analysis, in the time domain, of the waveform of the light burst generated as it crosses an observation window of known dimensions. A theoretical analysis of the parameters affecting the visibility of the particles in an argon plasma showed that depending on the particle diameter and its surface temperature, its thermal visibility factor will drop sharply from 1.0 to almost zero, with the increase of the background plasma temperature. Measurements are carried out using nickel particles (mathp=78 μm, σ=18.0 μm) injected axially into an inductively coupled rf plasma ( f=3 MHz, P=15 kW) operated using argon as the plasma gas at atmospheric pressure and under soft vacuum conditions (p=760 and 150 Torr). The results are in good agreement with particle velocity data obtained using laser Doppler anemometry. The measured, in‐flight, particle size distribution is consistent with optical microscopic measurement of the particle size distribution of the injected powder.
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07.60.-j Optical instruments and equipment
47.80.-v Instrumentation and measurement methods in fluid dynamics
52.40.Mj Particle beam interactions in plasmas
06.30.-k Measurements common to several branches of physics and astronomy

Performance of a gas spring harmonic oscillator

R. Del Fabbro, A. Di Virgilio, A. Giazotto, H. Kautzky, V. Montelatici, and D. Passuello

Rev. Sci. Instrum. 59, 292 (1988); http://dx.doi.org/10.1063/1.1140243 (6 pages) | Cited 19 times

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The characteristics and the performances of a gas spring, to be used in the future in a three‐dimensional multiple attenuation system, designed to support the heavy test masses for a low‐frequency gravitational wave interferometric antenna, are presented. This multiple system is expected to attenuate 10−9 (10−11) at 10 Hz in the vertical (horizontal) direction. This experiment, in which masses up to 430 kg have been levitated, has shown that the height of the resonance peaks in the gas spring vertical and horizontal transfer functions should not prevent us from obtaining the required high attenuation factors. A gas temperature feedback system, for the gas volume control, has given satisfactory results.
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07.10.-h Mechanical instruments and equipment
06.60.Vz Workshop procedures (welding, machining, lubrication, bearings, etc.)
04.80.-y Experimental studies of gravity

Comparison between two‐wire and three‐wire models for shielded twisted‐pair cables used in Johnson noise thermometry

M. J. Roberts

Rev. Sci. Instrum. 59, 298 (1988); http://dx.doi.org/10.1063/1.1140244 (6 pages) | Cited 1 time

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Using typical values of cable parameters and typical connections used in Johnson noise thermometry, a comparison was made between a two‐wire and a three‐wire transmission line model of a 30‐m‐long, shielded, twisted‐pair cable over a range of frequencies from 0 to 300 kHz. For a 200‐Ω source impedance and a 1‐MΩ load impedance, the maximum difference between the voltage transfer functions calculated from the two models was 0.415%. For a 500‐Ω source impedance, the maximum difference was 0.607%. For a 200‐Ω source impedance and a 1‐Ω load impedance, the maximum difference between the current transfer functions calculated from the two models was 4.24%. For a 500‐Ω source impedance, the maximum difference was approximately 4.47%.
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07.20.Dt Thermometers
84.32.Hh Inductors and coils; wiring

Nonmagnetic metal and glass helium‐3 cryostat immersed in a 4.2‐K bath

P. J. Nacher, G. Tastevin, and L. Wiesenfeld

Rev. Sci. Instrum. 59, 304 (1988); http://dx.doi.org/10.1063/1.1140245 (3 pages)

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A simple helium‐3 cryostat operating down to 400 mK is described. It is very weakly magnetic, easy to take apart, and allows optical access to the coldest part.
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07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
67.10.Hk Quantum effects on the structure and dynamics of non-degenerate fluids
67.30.-n 3He
67.25.bh Films and restricted geometries

Improved magnetic suspension densimeter for biochemical reactions

G. T. Gillies and D. W. Kupke

Rev. Sci. Instrum. 59, 307 (1988); http://dx.doi.org/10.1063/1.1140246 (7 pages) | Cited 4 times

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An improved version of our magnetic suspension densimeter has been developed for use with samples of aqueous systems as small as 100 μl. The instrument’s sensitivity to a change in density of the solution under test (measured as a voltage shift) is 0.1 mV≊4.5×10−6 g ml−1, with a base‐line drift less than 9 μV/h. The nonlinearity of the densimeter’s response is less than 5 ppm over its calibration range. In this paper, we describe the new magnetic suspension circuit, discuss the precision limits of the instrument, and present the results of measurements made on a tetracarboxylate sequestering agent known as BAPTA which we use as a calcium‐ion indicator.
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87.80.-y Biophysical techniques (research methods)
87.15.Nn

A transit‐time flow meter for measuring milliliter per minute liquid flow

Canqian Yang, M. Kümmel, and H. Søeberg

Rev. Sci. Instrum. 59, 314 (1988); http://dx.doi.org/10.1063/1.1140247 (4 pages) | Cited 2 times

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A transit‐time flow meter, using periodic temperature fluctuations as tracers, has been developed for measuring liquid flow as small as 0.1 ml/min in microchannels. By injecting square waves of heat into the liquid flow upstream with a tiny resistance wire heater, periodic temperature fluctuations are generated downstream. The fundamental frequency phase shift of the temperature signal with respect to the square wave is found to be a linear function of the reciprocal mean velocity of the fluid. The transit‐time principle enables the flow meter to have high accuracy, better than 0.2%, and good linearity. This flow meter will be used to measure and control the small liquid flow in microchannels in flow injection analysis.
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47.80.-v Instrumentation and measurement methods in fluid dynamics
07.05.Hd Data acquisition: hardware and software
07.05.Kf Data analysis: algorithms and implementation; data management
07.05.Rm Data presentation and visualization: algorithms and implementation

Pressure profiles at multimegabar pressures in a diamond anvil cell using x‐ray diffraction

Keith E. Brister, Yogesh K. Vohra, and Arthur L. Ruoff

Rev. Sci. Instrum. 59, 318 (1988); http://dx.doi.org/10.1063/1.1140248 (4 pages) | Cited 8 times

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Pressure distributions in a diamond anvil cell with a rhenium gasket have been measured at various pressures up to 212±6 GPa using energy dispersive x‐ray diffraction with a synchrotron source. Three sets of type IA yellow diamonds were used with bevels of 5°, 7°, and 10°. For the 7°‐beveled tips, a 5‐μm‐diam collimated beam was used to a pressure of 206±6 GPa. In the other experiments, collimators of 10–30 μm were used. In the region of the 50‐μm central flat, the pressure was essentially uniform. The effect of finite collimator size on the measurement of pressure profiles is also analyzed.
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07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
61.05.cf X-ray scattering (including small-angle scattering)
61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.
62.50.-p High-pressure effects in solids and liquids

Powder aspirator for shock tube studies of heterogeneous reactions

M. T. Cheng, M. J. Kirsch, and T. W. Lester

Rev. Sci. Instrum. 59, 322 (1988); http://dx.doi.org/10.1063/1.1140249 (6 pages)

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The application of single‐pulse shock tube techniques in the study of heterogeneous reactions is described. In particular, nitric oxide removal on carbonaceous materials at temperatures simulating pulverized coal firing is reported. Carbon black particulates were suspended and heated behind reflected shock waves in order to simulate flame‐borne particulates. To meet the specific requirement of preshock conditions, a novel and simple powder aspirator was designed and fabricated for dispersing carbon black. Particle concentrations measured by a gravimetric method and by in‐line light transmission were compared. Changes of nitric oxide concentration, reaction products and volatile species emitted from the particulates were analyzed with gas chromatographic techniques. Representative results of nitric oxide reduction by carbon black particulates at concentrations up to 50 g/m3 are provided, and indicate that single‐pulse shock tubes coupled with a simple powder aspirator may be used to infer global rates for gas/solid reactions of potential importance in combustion.
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82.33.Vx Reactions in flames, combustion, and explosions
82.80.Bg Chromatography
07.20.Ka High-temperature instrumentation; pyrometers

Fast analog chopper multiplexer for oscilloscope recording of single‐shot events

P. Choi and E. Wyndham

Rev. Sci. Instrum. 59, 328 (1988); http://dx.doi.org/10.1063/1.1140250 (4 pages)

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The design and construction of an electronic circuit to multiplex two analog signals for display by trace chopping on a fast single‐beam oscilloscope is presented. The circuit uses a Schottky ring diode modulator as a control switch and is unique in having a chopping frequency of up to 400 MHz with switching times between channels of less than 0.7 ns. Used with an oscilloscope with sufficient bandwidth, it is then possible to obtain pseudosimultaneous display of fast single‐shot events. In conjunction with a Tektronix 7834 oscilloscope with a 7A19 plug in, the maximum signal bandwidth of the prototype is measured to be 150 MHz, and the interchannel rejection ratio greater than 24 dB at a chopping frequency of 200 MHz.
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84.30.Qi Modulators and demodulators; discriminators, comparators, mixers, limiters, and compressors
07.50.Ek Circuits and circuit components

Fast calibration of an infrared vidicon

W. Freude

Rev. Sci. Instrum. 59, 332 (1988); http://dx.doi.org/10.1063/1.1140251 (4 pages) | Cited 1 time

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Infrared vidicon tubes of the type N 214 from Hamamatsu have widespread use for various measurements in the field of optical communication, in spite of their severe drawbacks such as poor stability and low accuracy. Usually, they interface with a desktop computer as a controller, so that the influences of dark current, shading, and nonlinearity may be corrected. With a specially designed computer‐controlled lamp and an optimized algorithm, it is possible to calibrate the vidicon very fast. Dark current, shading, and nonlinearities result in errors less than 9% and are mainly determined by the strong thermal drift of the tube. Because of the least‐squares‐fitting technique, the calibration is very noise insensitive.
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84.47.+w Vacuum tubes
85.60.Ha Photomultipliers; phototubes and photocathodes
07.05.Hd Data acquisition: hardware and software
07.05.Kf Data analysis: algorithms and implementation; data management
07.05.Rm Data presentation and visualization: algorithms and implementation
42.72.-g Optical sources and standards

Simple method for analog measurement of amplitude probability functions of stationary signals

A. Castellano, G. F. Palamá, and J. C. Guerci

Rev. Sci. Instrum. 59, 336 (1988); http://dx.doi.org/10.1063/1.1140200 (3 pages)

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An apparatus for the measurement of the amplitude density function and cumulative distribution function of stationary signals is described. The apparatus proposed does not require the use of the multichannel analyzer methods of amplitude sampling and analysis but employs only instruments in general use in research laboratories.
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07.50.Ek Circuits and circuit components
84.30.Sk Pulse and digital circuits
84.47.+w Vacuum tubes

Teflon cell for electrical conductivity studies in molten fluorides

A. M. Elias

Rev. Sci. Instrum. 59, 339 (1988); http://dx.doi.org/10.1063/1.1140273 (3 pages)

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A novel conductivity cell for fluoride systems with a low melting point is reported. The instrument concerned is made of Teflon and has bright platinum electrodes. It may be used up to 170 °C. The value of the cell constant is 27.91±0.06 cm−1. The cell may be used with other values of the constant upon changing the capillary diameter of the horizontal cylindrical piece.
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07.50.-e Electrical and electronic instruments and components
06.60.Ei Sample preparation (including design of sample holders)
81.70.-q Methods of materials testing and analysis
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