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Feb 2004

Volume 75, Issue 2, pp. 293-567

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Astrophysical neutrino telescopes

A. B. McDonald, C. Spiering, S. Schönert, E. T. Kearns, and T. Kajita

Rev. Sci. Instrum. 75, 293 (2004); http://dx.doi.org/10.1063/1.1642740 (24 pages) | Cited 10 times

Online Publication Date: 29 January 2004

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This review describes telescopes designed to study neutrinos from astrophysical sources. These sources include the sun and supernovae emitting neutrino energies up to tens of MeV, atmospheric neutrino sources caused by cosmic ray interactions, and other sources generating neutrino energies ranging up to 1×1020 eV. Measurements with these telescopes also provide information on neutrino properties, including clear evidence for neutrino flavor change. Telescopes in operation in the past and present are described, along with plans for future instruments to expand this rapidly growing field of particle astrophysics. © 2004 American Institute of Physics.
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95.55.Vj Neutrino, muon, pion, and other elementary particle detectors; cosmic ray detectors
96.50.S- Cosmic rays
96.50.Vg Energetic particles
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back to top OPTICS; ATOMS and MOLECULES; SPECTROSCOPY; PHOTON DETECTORS

Optical single-angle plane-wave transmittances/reflectances from Schwarzschild objective variable-angle measurements

Thomas K. Gaylord and Gregory R. Kilby

Rev. Sci. Instrum. 75, 317 (2004); http://dx.doi.org/10.1063/1.1641160 (7 pages) | Cited 2 times

Online Publication Date: 29 January 2004

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Photonic crystal structures and other nanoscale and microscale optical structures are centrally important to future device technology. The fundamental infrared single-angle plane-wave experimental characterization of these structures is needed to evaluate the analysis, design, and fabrication progress on these devices. The very small sizes of these devices necessitates focusing the infrared probe light typically with a Schwarzschild reflecting objective. The small spot size inherently requires the large range of incident angles associated with the objective. In this work, a variable-angle measurement method is presented for obtaining the optical single-angle plane-wave transmittances/reflectances. The primary steps in this method are (1) calculating the reference sample single-angle plane-wave transmittance/reflectance, (2) measuring the composite transmittances/reflectances of a reference sample over a range of objective angles of incidence, (3) calculating the intensity-angular-weighting coefficients for the objective using the Moore–Penrose (overdetermined linear equations) matrix inversion technique, (4) measuring the composite transmittances/reflectances of a sample-under-test over a range of objective angles of incidence, and (5) calculating the single-angle plane-wave transmittances/reflectances using the Moore–Penrose matrix inversion technique. © 2004 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
07.60.-j Optical instruments and equipment

Velocity-map imaging electron spectrometer with time resolution

B. Baguenard, J. B. Wills, F. Pagliarulo, F. Lépine, B. Climen, M. Barbaire, C. Clavier, M. A. Lebeault, and C. Bordas

Rev. Sci. Instrum. 75, 324 (2004); http://dx.doi.org/10.1063/1.1642749 (5 pages) | Cited 21 times

Online Publication Date: 29 January 2004

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A velocity-map imaging system for time-resolved photoelectron spectroscopy is presented and discussed. Nanosecond gating of microchannel plates synchronized with the excitation laser in a velocity-map imaging spectrometer has been used to generate time-resolved images of electrons emitted from photoexcited xenon atoms and small carbon cluster anions. These images represent a time slice in the kinetic energy spectrum and reveal the differing time scales of competing electron emission processes. © 2004 American Institute of Physics.
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07.81.+a Electron and ion spectrometers
79.60.-i Photoemission and photoelectron spectra
36.40.Cg Electronic and magnetic properties of clusters
32.80.Fb Photoionization of atoms and ions

High-power 47.6 and 57.2 μm CH3OD lasers pumped by continuous-wave 9R(8) CO2 laser

K. Nakayama, H. Tazawa, S. Okajima, K. Kawahata, K. Tanaka, T. Tokuzawa, and Y. Ito

Rev. Sci. Instrum. 75, 329 (2004); http://dx.doi.org/10.1063/1.1642742 (4 pages) | Cited 11 times

Online Publication Date: 29 January 2004

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Powerful lasers in the far-infrared wavelength range (47.6 and 57.2 μm) have been developed to measure the plasma density in the Large Helical Device at National Institute for Fusion Science and future plasma devices such as the International Thermonuclear Experimental Reactor. The intensification of these lasers has been done by cooling the laser tube wall, adding He as the buffer gas, and using a chemical-vapor-deposited diamond output window. The output powers for the 57.2 and 47.6 μm lasers have been found to be 1.6 and 0.8 W, respectively. © 2004 American Institute of Physics.
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42.60.By Design of specific laser systems
42.55.Lt Gas lasers including excimer and metal-vapor lasers
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
42.79.Ci Filters, zone plates, and polarizers
back to top PARTICLE SOURCES, OPTICS and ACCELERATION; PARTICLE DETECTORS

Fast infrared array spectrometer with a thermoelectrically cooled 160-element PbSe detector

Jun Ji, Jay P. Gore, Yudaya R. Sivathanu, and Jongmook Lim

Rev. Sci. Instrum. 75, 333 (2004); http://dx.doi.org/10.1063/1.1634362 (7 pages) | Cited 3 times

Online Publication Date: 29 January 2004

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A fast infrared array spectrometer (FIAS) with a thermoelectrically cooled 160-element PbSe detector was demonstrated using measurements of instantaneous infrared radiation intensities simultaneously over the 1.8–4.9 μm wavelength range at a sampling rate of 390 Hz. A three-point second-degree Lagrange interpolation polynomial was constructed to calibrate the FIAS because of the nonlinear response of the infrared array detector to the incident radiation beam. This calibration method gave excellent measurements of blackbody radiation spectra except for a narrow band at wavelength of 4.3 μm due to absorption by room carbon dioxide, which is one of the two major gas radiation peaks (2.7 and 4.3 μm) from the lean premixed hydrocarbon/air combustion products in the midinfrared spectrum. Therefore, the absorption coefficient of room carbon dioxide was conveniently measured on site with the blackbody reference source, and was used in the calibration of the FIAS and also in the calculations of the radiation spectra. Blackbody tests showed that this procedure was effective in correcting for the room carbon dioxide absorption in the radiation spectra measured by the FIAS. For an example of its application, the calibrated FIAS was used to measure spectral radiation intensities from three lean premixed laminar flames and a premixed turbulent jet flame for which reference data with a grating spectrometer were available for comparison. The agreement between the FIAS measurements and the reference data was excellent. © 2004 American Institute of Physics.
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07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
85.60.Gz Photodetectors (including infrared and CCD detectors)
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
72.80.Jc Other crystalline inorganic semiconductors
06.20.F- Units and standards

Cryogenic neutron detector comprising an InSb semiconductor detector and a supercritical helium-3 gas converter

Tatsuya Nakamura, Masaki Katagiri, Yasuyuki Aratono, Ikuo Kanno, Shigeomi Hishiki, Osamu Sugiura, and Yasuhiro Murase

Rev. Sci. Instrum. 75, 340 (2004); http://dx.doi.org/10.1063/1.1642747 (5 pages) | Cited 3 times

Online Publication Date: 29 January 2004

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We evaluated the neutron-detection characteristics of a proposed cryogenic neutron detector comprising an InSb semiconductor detector and a helium-3 gas converter. The neutron detector was operated at 4.2 K with helium-3 gas filling up to 1.5 atm, at which the density of the helium-3 nucleus corresponds to that at 160 atm at room temperature. The secondary particles generated by the 3He(n,p)T reaction were successfully detected by the InSb detector with a time response of ∼80 ns at all tested gas pressures. © 2004 American Institute of Physics.
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29.40.Cs Gas-filled counters: ionization chambers, proportional, and avalanche counters
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment

Source for atomic beams of metastable gases: Design and performance

M. DeKieviet, M. Dürr, S. Epp, F. Lang, and M. Theis

Rev. Sci. Instrum. 75, 345 (2004); http://dx.doi.org/10.1063/1.1638869 (4 pages) | Cited 7 times

Online Publication Date: 29 January 2004

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There is an increasing interest in high flux sources of metastable species in many scientific communities, for example for lithography and quantum optics experiments. We present a simple dc discharge design, based on microstructured electrodes (MSE), for the production of truly thermal beams of metastable atoms. Even for inlet pressures above 1 atm the discharge runs stably, at relatively modest voltages. Time-of-flight data prove that the expansion is supersonic with speed ratios up to 8.5 and internal temperatures of less than 10 K. The MSE source works equally well for many different gases like He, Ne, Kr, Ar, H2, and N2. Its measured yield of ∼ 1014 metastable atoms s−1 sr−1 compares favorably with conventional discharge sources. In addition, its simple design holds good promise for cooling the source down to cryogenic temperatures. © 2004 American Institute of Physics.
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37.20.+j Atomic and molecular beam sources and techniques
07.77.Gx Atomic and molecular beam sources and detectors
07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment
07.60.-j Optical instruments and equipment
52.80.Hc Glow; corona

A simple and compact mechanical velocity selector of use to analyze/select molecular alignment in supersonic seeded beams

F. Pirani, D. Cappelletti, F. Vecchiocattivi, L. Vattuone, A. Gerbi, M. Rocca, and U. Valbusa

Rev. Sci. Instrum. 75, 349 (2004); http://dx.doi.org/10.1063/1.1637433 (6 pages) | Cited 12 times

Online Publication Date: 29 January 2004

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A light and compact mechanical velocity selector, of novel design, for applications in supersonic molecular-beam studies has been developed. It represents a simplified version of the traditional, 50 year old, slotted disks velocity selector. Taking advantage of new materials and improved machining techniques, the new version has been realized with only two rotating slotted disks, driven by an electrical motor with adjustable frequency of rotation, and thus has a much smaller weight and size with respect to the original design, which may allow easier implementation in most of the available molecular-beam apparatuses. This new type of selector, which maintains a sufficiently high velocity resolution, has been developed for sampling molecules with different degrees of rotational alignment, like those emerging from a seeded supersonic expansion. This sampling is the crucial step to realize new molecular-beam experiments to study the effect of molecular alignment in collisional processes. © 2004 American Institute of Physics.
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37.20.+j Atomic and molecular beam sources and techniques
82.37.-j Single molecule kinetics

Multicusp ion source with external rf antenna for production of protons

S. K. Hahto, S. T. Hahto, Q. Ji, K. N. Leung, S. Wilde, E. L. Foley, L. R. Grisham, and F. M. Levinton

Rev. Sci. Instrum. 75, 355 (2004); http://dx.doi.org/10.1063/1.1642744 (5 pages) | Cited 7 times

Online Publication Date: 29 January 2004

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Proton beams are needed in neutral-beam injection for diagnostic development of an internal magnetic field measurement. High proton fraction, low axial energy spread, current density in excess of 30 mA/cm2, and a parallel ion beam with cw operation are the requirements for the ion source/extraction system. A multicusp-type ion source with an external rf antenna was constructed at Lawrence Berkeley National Laboratory. A proton fraction of 85% and proton current density of 32 mA/cm2 were achieved at 1.8 kW of rf power. Plasma parameters were measured with a rf compensated Langmuir probe. © 2004 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors
52.70.Ds Electric and magnetic measurements

Data analysis process of a toroidal analyzer for electron–ion collision experiments

Jun Matsumoto, Nobuo Kobayashi, Atsunori Danjo, and Masuhiro Yoshino

Rev. Sci. Instrum. 75, 360 (2004); http://dx.doi.org/10.1063/1.1642746 (7 pages) | Cited 1 time

Online Publication Date: 29 January 2004

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A toroidal analyzer has been developed to measure angular differential cross sections for electron scattering in electron–ion collisions. Energy and angular dispersed electron images are recorded by using a two-dimensional position sensitive detector. Operation and calibration of the analyzer are described with particular emphasis on a procedure to deduce the differential cross sections from the acquired two-dimensional data. Angular differential cross sections for elastic scattering of electrons from Ar7+ and Ar8+ ions are presented in the angular range from 34° to 85° at a collision energy of 100 eV in the center of mass frame. © 2004 American Institute of Physics.
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34.80.Bm Elastic scattering
34.80.Dp Atomic excitation and ionization
07.77.Ka Charged-particle beam sources and detectors
37.20.+j Atomic and molecular beam sources and techniques

Heavy ions dynamic simulations in CYTRACK cyclotron

Yu. N. Denisov, V. V. Kalinichenko, and G. A. Karamysheva

Rev. Sci. Instrum. 75, 367 (2004); http://dx.doi.org/10.1063/1.1638876 (3 pages)

Online Publication Date: 29 January 2004

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The basic results of numeric simulations of heavy-ion motion in cyclotron CYTRACK are presented. Computer modeling confirms the possibility of ion acceleration and effective extraction. The experimental data completely support theoretical results presented. © 2004 American Institute of Physics.
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29.20.dg Cyclotrons
41.75.Ak Positive-ion beams
41.85.-p Beam optics
back to top NUCLEAR PHYSICS, FUSION and PLASMAS

Development of an electrostatic dust detector for use in a tokamak reactor

A. Bader, C. H. Skinner, A. L. Roquemore, and S. Langish

Rev. Sci. Instrum. 75, 370 (2004); http://dx.doi.org/10.1063/1.1637438 (6 pages) | Cited 15 times

Online Publication Date: 29 January 2004

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Initial results from a novel device to detect dust particles settling on remote surfaces are presented. Dust particle inventories are a concern in next-step fusion devices. The increase in duty cycle will lead to a scale-up in the amount of particles generated by plasma material interactions. These particles will be chemically and radiologically hazardous and it will be important to establish that the in-vessel particle inventory is within regulatory limits. The detection device consists of two interlocking combs of closely spaced conductive traces on a Teflon circuit board. When a direct current bias is applied, impinging dust creates a transient short circuit between the traces. The increase in bias current generates a signal pulse that is counted by standard nuclear counting electronics. We present data on the response of the device in air and vacuum to carbon particles. © 2004 American Institute of Physics.
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52.55.Fa Tokamaks, spherical tokamaks
52.70.Nc Particle measurements
52.77.Bn Etching and cleaning

Time resolved radiated power during tokamak disruptions and spectral averaging of AXUV photodiode response in DIII-D

D. S. Gray, S. C. Luckhardt, L. Chousal, G. Gunner, A. G. Kellman, and D. G. Whyte

Rev. Sci. Instrum. 75, 376 (2004); http://dx.doi.org/10.1063/1.1642745 (6 pages) | Cited 10 times

Online Publication Date: 29 January 2004

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Silicon absolute extreme ultraviolet (AXUV) photodiodes have been employed in a disruption radiometer diagnostic for measurement of radiant power in the DIII-D tokamak with a 170 kHz bandwidth. This is motivated by a need to improve the understanding of radiative processes in tokamak disruptions. The diagnostic described in this article has a single line of sight though the central plasma. Accounting for the photon energy dependence of the AXUV photodiode responsivity is made possible by optical filtering, with the aid of spectra from an extreme ultraviolet survey spectrometer. The appropriate effective responsivity for interpretation of the data is lower than the nominal value typically used for the detector. In the current quench phase of disruptions, it is less than half the nominal value. Comparisons with results from a foil bolometer find good agreement. © 2004 American Institute of Physics.
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52.55.Fa Tokamaks, spherical tokamaks
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.35.Qz Microinstabilities (ion-acoustic, two-stream, loss-cone, beam-plasma, drift, ion- or electron-cyclotron, etc.)
07.60.Rd Visible and ultraviolet spectrometers
85.60.Dw Photodiodes; phototransistors; photoresistors

High-density and low electron temperature direct current reflex plasma source

E. I. Toader, V. Covlea, W. G. Graham, and P. G. Steen

Rev. Sci. Instrum. 75, 382 (2004); http://dx.doi.org/10.1063/1.1637459 (5 pages) | Cited 3 times

Online Publication Date: 29 January 2004

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A new type of direct current, high-density, and low electron temperature reflex plasma source, obtained as a hybrid between a modified hollow-cathode discharge and a Penning ionization gauge discharge is presented. The plasma source was tested in argon, nitrogen, and oxygen over a range pressure of 1.0–10−3 mbar, discharge currents 20–200 mA, and magnetic field 0–120 Gauss. Both external parameters, such as breakdown potential and the discharge voltage–current characteristic, and its internal parameters, like the electron energy distribution function, electron and ion densities, and electron temperature, were measured. Due to the enhanced hollow-cathode effect by the magnetic trapping of electrons, the density of the bulk plasma is as high as 1018 m−3, and the electron temperature is as low as a few tenths of electron volts. The plasma density scales with the dissipated power. Another important feature of this reflex plasma source is its high degree of uniformity, while the discharge bulk region is free of an electric field. © 2004 American Institute of Physics.
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52.50.Dg Plasma sources
52.80.Sm Magnetoactive discharges (e.g., Penning discharges)
52.55.Lf Field-reversed configurations, rotamaks, astrons, ion rings, magnetized target fusion, and cusps

Characterization of a nonequilibrium XeCl laser-plasma by a movable Faraday cup

D. Doria, A. Lorusso, F. Belloni, and V. Nassisi

Rev. Sci. Instrum. 75, 387 (2004); http://dx.doi.org/10.1063/1.1641157 (6 pages) | Cited 21 times

Online Publication Date: 29 January 2004

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In this work the experimental results of a nonequilibrium laser-plasma induced by an ultraviolet 308 nm excimer laser are reported. All measurements were performed fixing the laser energy at 70 mJ. It was concentrated on a 0.0099 cm2 spot by a convergent focal lens of 15 cm focal length. The utilized target was a 99.99% pure Cu disk. An 8 cm in diameter movable Faraday cup was developed in order to detect the plasma flow pulse at different positions along a drift tube. Analyzing the time-of-flight pulse under different cup bias voltage, we were able to distinguish the electron pulse, the suprathermal ions, and the thermal evolution of the plasma. In addition, by applying a breakdown voltage as polarizing cup voltage, we characterized the duration of the neutral component. To determine the system particle production efficiency, the total etched material per pulse, 0.235 μg, and the fractional ionization were measured. The expelled particle flux distribution was measured by an optical transmission analysis of a Cu deposited film on a glass substrate. The plasma flow was detected along its propagation axis, between 6 and 40 cm far from the target. The ablation process expelled particles with an initial velocity of 34 km/s, while the maximum ion concentration was 1 μs after the laser pulse. The plasma created propagates with a mean velocity of about 20 km/s. During the propagation, the longitudinal plasma dimension changed from 2.8 cm, near the target, to 31 cm at the maximum cup distance analyzed. At lowest distances, the cup signal wave forms presented a plateau due to the high dense plasma undergone to the space charge regime governed by the Child–Langmuir law. © 2004 American Institute of Physics.
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52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.30.-q Plasma dynamics and flow
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.Jm Ionization of plasmas
52.25.Kn Thermodynamics of plasmas

Shielded electrostatic probe for nonperturbing plasma measurements in Hall thrusters

D. Staack, Y. Raitses, and N. J. Fisch

Rev. Sci. Instrum. 75, 393 (2004); http://dx.doi.org/10.1063/1.1634353 (7 pages) | Cited 9 times

Online Publication Date: 29 January 2004

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Electrostatic probes are widely used to measure spatial plasma parameters of the quasineutral plasma in Hall thrusters and similar E×B electric discharge devices. Significant perturbations of the plasma induced by such probes can mask the actual physics involved in the operation of these devices. In Hall thrusters, probe-induced perturbations can produce changes in the discharge current and plasma parameters on the order of their steady-state values. These perturbations are explored by varying the material, penetration distance, and residence time of various probe designs. A possible cause of these perturbations appears to be the secondary electron emission, induced by energetic plasma electrons, from insulator ceramic tubes in which the probe wire is inserted. A new probe in which a low secondary electron emission material, such as metal, shields the probe ceramic tube, is shown to function without producing such large perturbations. A segmentation of this shield further prevents probe-induced perturbations, by not shortening the plasma through the conductive shield. In a set of experiments with a segmented shield probe, the thruster was operated in the input power range of 500 W–2.5 kW and discharge voltages of 200–500 V, while the probe-induced perturbations of the discharge current were below 4% of its steady-state value in the region in which 90% of the voltage drop takes place. © 2004 American Institute of Physics.
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52.70.Ds Electric and magnetic measurements
52.25.-b Plasma properties
52.75.Di Ion and plasma propulsion
back to top MICROSCOPY and IMAGING

Calibration of optical cantilever deflection readers

Zhiyu Hu, Tim Seeley, Sebastian Kossek, and Thomas Thundat

Rev. Sci. Instrum. 75, 400 (2004); http://dx.doi.org/10.1063/1.1637457 (5 pages) | Cited 10 times

Online Publication Date: 29 January 2004

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Because of its ultrahigh sensitivity, the optical lever detection method similar to that used in the atomic force microscope (AFM) has been widely employed as a standard technique for measuring microcantilever deflection. Along with the increasing interest in using the microcantilever as a sensing platform, there is also a requirement for a reliable calibration technique. Many researchers have used the concept of optical lever detection to construct microcantilever deflection readout instruments for chemical, physical, and biological detection. However, without an AFM piezo z scanner, it is very difficult to precisely calibrate these instruments. Here, we present a step-by-step method to conveniently calibrate an instrument using commercially available piezoresistive cantilevers. The experimental results closely match the theoretical calculation. Following this procedure, one can easily calibrate any optical cantilever deflection detection system with high reproducibility, precision, and reliability. A detailed discussion of the optical lever readout system design has been addressed in this article. © 2004 American Institute of Physics.
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07.10.Cm Micromechanical devices and systems
06.20.F- Units and standards
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
42.79.Fm Reflectors, beam splitters, and deflectors

Field ionization detection of supersonic molecular beams

R. B. Doak, Y. Ekinci, B. Holst, J. P. Toennies, T. Al-Kassab, and A. Heinrich

Rev. Sci. Instrum. 75, 405 (2004); http://dx.doi.org/10.1063/1.1642743 (10 pages) | Cited 10 times

Online Publication Date: 29 January 2004

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Seminal field ionization detection of a supersonic helium beam is reported, including intensity measurements on a continuous beam and time-of-flight measurements on a chopped beam. Also unique to these experiments is the care with which the field ionization tip was prepared and characterized prior to its use. Comparative measurements on a static helium gas are presented and the effective detection area of the field ionization tip is extracted for both beam and static gas. These areas are much smaller than those reported in previous experiments, suggesting that detection efficiency depends strongly on energy and momentum transfer during the initial atom–tip collision. © 2004 American Institute of Physics.
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07.77.Gx Atomic and molecular beam sources and detectors
37.20.+j Atomic and molecular beam sources and techniques
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
79.70.+q Field emission, ionization, evaporation, and desorption
68.49.Df Molecule scattering from surfaces (energy transfer, resonances, trapping)

Quantitative characterization of friction coefficient using lateral force microscope in the wearless regime

P. Bilas, L. Romana, B. Kraus, Y. Bercion, and J. L. Mansot

Rev. Sci. Instrum. 75, 415 (2004); http://dx.doi.org/10.1063/1.1637436 (7 pages) | Cited 15 times

Online Publication Date: 29 January 2004

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Absolute quantitative data from atomic force microscopy (AFM)/lateral force microscopy experiments are always difficult to obtain mainly due to the need of the normal force FN and the friction force FF calibration. In this article, we developed an experimental method which allows us to extract absolute quantitative friction data without calibrating any force when the relation between FN and FF is linear or only calibrating the normal force when the relationship is nonlinear. The technique reported here, is suitable for an atomic force microscope that has the cantilever attached to the piezotube translator and an unguided incident laser beam on the cantilever. We take advantage of the piezotube bending during a large scan (5 μm×5 μm), generally considered as an undesirable effect, to calculate a detection factor that allows the determination of quantitative tribological data. The validity of our experimental method is checked on the extensively AFM studied materials, such as muscovite, silicon, and highly oriented pyrolytic graphite. The experiments are carried out in a load range where the shear stress τ can be expressed as τ = τ0+μP, where μ is the friction coefficient, P is the mean contact pressure, and τ0 is a parameter related to the tip/sample adhesion. The value of μ is found to be independent of the tip geometry and the pull-off force, and always constant for a given tip/sample couple in the load range investigated. © 2004 American Institute of Physics.
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81.40.Pq Friction, lubrication, and wear
62.20.Qp Friction, tribology, and hardness
07.10.Pz Instruments for strain, force, and torque

Sub-10 nm lateral spatial resolution in scanning capacitance microscopy achieved with solid platinum probes

E. Bussmann and C. C. Williams

Rev. Sci. Instrum. 75, 422 (2004); http://dx.doi.org/10.1063/1.1641161 (4 pages) | Cited 13 times

Online Publication Date: 29 January 2004

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Sub-10 nm resolution can be obtained in scanning capacitance microscopy (SCM) if the probe tip is approximately of the same size. Such resolution is observed, although infrequently, with present commercially available probes. To acquire routine sub-10 nm resolution, a solid Pt metal probe has been developed with a sub-10 nm tip radius. The probe is demonstrated by SCM imaging on a cross-sectioned 70 nm gatelength field-effect transistor (FET), a shallow implant (n+/p, 24 nm junction depth), and an epitaxial staircase (p, ∼75 nm steps). Sub-10 nm resolution is demonstrated on the FET device over the abrupt meeting between a silicon-on-insulator oxide layer and a neighboring Si region. Comparable resolution is observed on the implant structure, and quantitative SCM dopant profiling is performed on it with sub-10 nm accuracy. Finally, the epitaxial staircase structure is quantitatively profiled demonstrating the accuracy obtained in quantitative profiling with the tips. © 2004 American Institute of Physics.
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07.79.-v Scanning probe microscopes and components
85.30.Tv Field effect devices

Transmission electron microscopy specimen holder for simultaneous in situ heating and electrical resistance measurements

M. A. Verheijen, J. J. T. M. Donkers, J. F. P. Thomassen, J. J. van den Broek, R. A. F. van der Rijt, M. J. J. Dona, and C. M. Smit

Rev. Sci. Instrum. 75, 426 (2004); http://dx.doi.org/10.1063/1.1611616 (4 pages)

Online Publication Date: 29 January 2004

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A transmission electron microscopy (TEM) specimen holder has been developed for the measurement of the electrical resistance of a TEM sample as a function of temperature. A custom TEM heating holder was modified for this purpose. Eight feedthrough wires were passed through the specimen holder; (i) providing current to the heater, (ii) allowing for the measurement of the hot stage temperature, and (iii) enabling the measurement of the electrical resistance of the sample. This configuration creates the opportunity to directly correlate changes in the resistance to microstructural changes as a function of temperature. The working of the holder is demonstrated by studies on a phase transformation in Al–Ge films. In this way, a direct correlation was found between changes in resistance and microstructure as a function of temperature. © 2004 American Institute of Physics.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers
68.37.Lp Transmission electron microscopy (TEM)
06.60.Ei Sample preparation (including design of sample holders)
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
back to top CONDENSED MATTER; MATERIALS

Simulations and measurements of the performance of a channeled neutron guide for a time-of-flight spectrometer at the NIST Center for Neutron Research

Jeremy C. Cook and John R. D. Copley

Rev. Sci. Instrum. 75, 430 (2004); http://dx.doi.org/10.1063/1.1638871 (10 pages) | Cited 1 time

Online Publication Date: 29 January 2004

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We describe the identification and analysis of the principal sources of intensity loss within the five-channeled neutron guide tube that was originally installed in the chopper section of the Disk Chopper Spectrometer at the National Institute of Standards and Technology Center for Neutron Research. (The purpose of the five channels was to optimize intensity and resolution in three different modes of operation known as “resolution modes.”) By combining measurements, Monte Carlo simulations, and analytical calculations, we have developed a model that successfully explains performance losses in the original guide. We have used this model to quantify expected returns in performance using a replacement guide in which the principal contributions to the intensity loss are reduced to the minimum achievable with current technology. We have also estimated the intensity gains that would be achieved if one of the limited number of options were adopted for modifying the original guide in a manner likely to produce such gains. We describe factors that affect the performance of the original guide and compare the measured and predicted performance of the modified guide against predictions for the optimal replacement guide. The simulations indicate that the modified guide (which has three channels rather than the original five) produces greater intensity gains over a large incident wavelength band for the low and medium resolution modes, whereas a high quality replacement guide greatly improves performance in the high resolution mode of operation. Because the low and medium resolution modes are most heavily demanded, we opted to modify the guide rather than replace it. We describe the nature of this modification and present intensity measurements that meet or exceed predictions in all resolution modes with no detectable change in the energy resolution nor increase in the instrumental background. © 2004 American Institute of Physics.
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29.30.Hs Neutron spectroscopy

High-pressure cell for small- and medium-angle neutron scattering measurements up to 300 MPa

M. Bonetti and P. Calmettes

Rev. Sci. Instrum. 75, 440 (2004); http://dx.doi.org/10.1063/1.1637434 (5 pages) | Cited 5 times

Online Publication Date: 29 January 2004

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We describe a high-pressure cell designed for small- and medium-angle neutron scattering measurements on fluid samples under hydrostatic pressure up to 300 MPa. The cell is fitted up with two thick sapphire windows with a large forward optical aperture. For a neutron beam of 7 mm in diameter the maximum forward scattering angle is 15°. With a neutron wavelength of 0.41 nm this allows scattering spectra to be recorded for wave-number transfers up to 4 nm−1. The optical path length was 5 mm. However, it can be easily varied according to the sample under study. © 2004 American Institute of Physics.
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87.64.Bx Electron, neutron and x-ray diffraction and scattering
07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells

An inverse photoemission system with large solid angle of detection and adjustable optical bandpass

J. A. Lipton-Duffin, A. G. Mark, G. K. Mullins, G. E. Contant, and A. B. McLean

Rev. Sci. Instrum. 75, 445 (2004); http://dx.doi.org/10.1063/1.1637435 (10 pages) | Cited 6 times

Online Publication Date: 29 January 2004

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A high-brightness, low energy electron source and dual Geiger–Müller-type isochromat photon detectors are combined to create a versatile new inverse photoemission system. The bandpass of the photon detector can be set to one of the following discrete values: 0.37±0.02, 0.43±0.02, 0.56±0.02, or 0.73±0.04 eV by using ethanol, 1-propanol, 1-butanol, or a dimethyl ether/ethanol mixture, respectively, as the detection gas(es). All of the alcohols are self-quenching and do not require the addition of a quench gas. The design of the photon detectors, the electron gun, and the circuits that perform the dead time gating are described in detail. The capabilities of the new system are illustrated using spectra from both metal (Cu) and semiconductor (Si) surfaces. © 2004 American Institute of Physics.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
07.77.Ka Charged-particle beam sources and detectors
78.70.-g Interactions of particles and radiation with matter
07.81.+a Electron and ion spectrometers

Wide-field spectroscopy for optical characterization of the pulsed laser deposition plume

E. Pérez-Tijerina, R. Machorro, and J. Bohigas

Rev. Sci. Instrum. 75, 455 (2004); http://dx.doi.org/10.1063/1.1637458 (7 pages) | Cited 1 time

Online Publication Date: 29 January 2004

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A technique to study several regions of plasma produced by laser ablation in a single laser pulse is presented. The technique is based on a field spectrograph, an instrument where the image of the plasma is captured with a number of fibers in a user defined array, and then projected into the one-dimensional slit of a spectrograph. With this instrument, we can obtain the spectra of a discrete number of regions in the plume and reconstruct the image of the plasma at different wavelengths. Several examples of interest in the field of pulsed laser deposition are given. © 2004 American Institute of Physics.
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52.77.Dq Plasma-based ion implantation and deposition
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
42.81.Wg Other fiber-optical devices
07.60.Rd Visible and ultraviolet spectrometers
81.15.Fg Pulsed laser ablation deposition
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