Rev. Sci. Instrum. - Review of Scientific Instruments

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A simplified 461-nm laser system using blue laser diodes and a hollow cathode lamp for laser cooling of Sr

Yosuke Shimada, Yuko Chida, Nozomi Ohtsubo, Takatoshi Aoki, Makoto Takeuchi, Takahiro Kuga, and Yoshio Torii

Rev. Sci. Instrum. 84, 063101 (2013); http://dx.doi.org/10.1063/1.4808246 (7 pages)

Online Publication Date: 6 June 2013

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We develop a simplified light source at 461 nm for laser cooling of Sr without frequency-doubling crystals but with blue laser diodes. An anti-reflection coated blue laser diode in an external cavity (Littrow) configuration provides an output power of 40 mW at 461 nm. Another blue laser diode is used to amplify the laser power up to 110 mW by injection locking. For frequency stabilization, we demonstrate modulation-free polarization spectroscopy of Sr in a hollow cathode lamp. The simplification of the laser system achieved in this work is of great importance for the construction of transportable optical lattice clocks.

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42.50.Wk	Mechanical effects of light on material media, microstructures and particles
42.55.Px	Semiconductor lasers; laser diodes
42.60.Da	Resonators, cavities, amplifiers, arrays, and rings
42.60.Fc	Modulation, tuning, and mode locking
37.10.Gh	Atom traps and guides
37.10.Vz	Mechanical effects of light on atoms, molecules, and ions

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Compact high-flux source of cold sodium atoms

G. Lamporesi, S. Donadello, S. Serafini, and G. Ferrari

Rev. Sci. Instrum. 84, 063102 (2013); http://dx.doi.org/10.1063/1.4808375 (7 pages)

Online Publication Date: 7 June 2013

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We present a compact source of cold sodium atoms suitable for the production of quantum degenerate gases and versatile for a multi-species experiment. The magnetic field produced by permanent magnets allows to simultaneously realize a Zeeman slower and a two-dimensional magneto-optical trap (MOT) within an order of magnitude smaller length than standard sodium sources. We achieve an atomic flux exceeding 4 × 10⁹ atoms/s loaded in a MOT, with a most probable longitudinal velocity of 20 m/s, and a brightness larger than 2.5 × 10¹² atoms/s/sr. This atomic source allows us to produce pure Bose-Einstein condensates with more than 10⁷ atoms and a background pressure limited lifetime of 5 min.

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37.10.Gh	Atom traps and guides
37.10.Vz	Mechanical effects of light on atoms, molecules, and ions
42.50.Wk	Mechanical effects of light on material media, microstructures and particles
32.60.+i	Zeeman and Stark effects
37.10.-x	Atom, molecule, and ion cooling methods

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Simulated annealing–simplex hybrid algorithm for ellipsometric data inversion of multilayer films

Longfeng Fan and Zuohua Huang

Rev. Sci. Instrum. 84, 063103 (2013); http://dx.doi.org/10.1063/1.4808463 (4 pages)

Online Publication Date: 10 June 2013

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A simulated annealing–simplex hybrid algorithm that accurately measures the optical parameters of multilayer films is proposed for ellipsometric data inversion of multilayer films. In single-wavelength ellipsometry experiments, multiple groups of ellipsometric parameters measured by multiple incident angles can determine multiple optical parameters. Analysis of the measurement accuracy of multilayer films indicates that probabilities of uncertainty increase as films become thinner. Accurate measurements show that using the hybrid algorithm to obtain the optical parameters of multilayer films is feasible and reliable. The algorithm can be used for the inversion and the actual measurement of double-layer and multilayer films by single-wavelength ellipsometry.

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07.60.Fs	Polarimeters and ellipsometers
42.70.-a	Optical materials
42.79.Wc	Optical coatings
02.50.Cw	Probability theory

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High-intensity coherent vacuum ultraviolet source using unfocussed commercial dye lasers

Daniel R. Albert, David L. Proctor, and H. Floyd Davis

Rev. Sci. Instrum. 84, 063104 (2013); http://dx.doi.org/10.1063/1.4806801 (9 pages)

Online Publication Date: 11 June 2013

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Using two or three commercial pulsed nanosecond dye lasers pumped by a single 30 Hz Nd:YAG laser, generation of 0.10 mJ pulses at 125 nm (6 × 10¹³ photons/pulse) has been demonstrated by resonance enhanced four-wave mixing of collimated (unfocussed) laser beams in mercury (Hg) vapor. Phase matching at various vacuum ultraviolet (VUV) wavelengths is achieved by tuning one laser in the vicinity of the 6 ¹S₀ → 6 ³P₁ resonance near 253.1 nm. A number of different mixing schemes are characterized. Our observations using broadband lasers (∼0.15 cm⁻¹ bandwidths) are compared to previous calculations pertaining to four-wave mixing of low intensity narrowband laser beams. Prospects for further increases in pulse energies are discussed. We find that VUV tuning curves and intensities are in good agreement with theoretical predictions. The utility of the VUV light source is demonstrated by “soft universal” single-photon VUV ionization in crossed molecular beam studies and for generation of light at 130.2 nm for oxygen atom Rydberg time-of-flight experiments.

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42.72.Bj	Visible and ultraviolet sources
42.55.Mv	Dye lasers
42.79.Ag	Apertures, collimators
42.60.Jf	Beam characteristics: profile, intensity, and power; spatial pattern formation

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Development of an (e,2e) electron momentum spectroscopy apparatus using an ultrashort pulsed electron gun

M. Yamazaki, Y. Kasai, K. Oishi, H. Nakazawa, and M. Takahashi

Rev. Sci. Instrum. 84, 063105 (2013); http://dx.doi.org/10.1063/1.4809792 (10 pages)

Online Publication Date: 14 June 2013

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An (e,2e) apparatus for electron momentum spectroscopy (EMS) has been developed, which employs an ultrashort-pulsed incident electron beam with a repetition rate of 5 kHz and a pulse duration in the order of a picosecond. Its instrumental design and technical details are reported, involving demonstration of a new method for finding time-zero. Furthermore, EMS data for the neutral Ne atom in the ground state measured by using the pulsed electron beam are presented to illustrate the potential abilities of the apparatus for ultrafast molecular dynamics, such as by combining EMS with the pump-and-probe technique.

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07.81.+a	Electron and ion spectrometers
84.47.+w	Vacuum tubes

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Development of a cryogenic load frame for the neutron diffractometer at Takumi in Japan Proton Accelerator Research Complex

Xinzhe Jin, Tatsushi Nakamoto, Stefanus Harjo, Tsutomu Hemmi, Takahiro Umeno, Toru Ogitsu, Akira Yamamoto, Michinaka Sugano, Kazuya Aizawa, Jun Abe, Wu Gong, and Takaaki Iwahashi

Rev. Sci. Instrum. 84, 063106 (2013); http://dx.doi.org/10.1063/1.4810010 (4 pages)

Online Publication Date: 18 June 2013

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To prepare for projects such as the Large Hadron Collider upgrade, International Thermonuclear Experimental Reactor and Demonstration reactor, it is important to form a clear understanding of stress-strain properties of the materials that make up superconducting magnets. Thus, we have been studying the mechanical properties of superconducting wires using neutron diffraction measurements. To simulate operational conditions such as temperature, stress, and strain, we developed a cryogenic load frame for stress-strain measurements of materials using a neutron diffractometer at Japan Proton Accelerator Research Complex (J-PARC) Takumi beam line. The maximum load that can be applied to a sample using an external driving machine is 50 kN. Using a Gifford–MacMahon cryocooler, samples can be measured down to temperatures below 10 K when loaded. In the present paper, we describe the details of the cryogenic load frame with its test results by using type-304 stainless steel wire.

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29.20.-c	Accelerators
07.20.Mc	Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
84.71.Ba	Superconducting magnets; magnetic levitation devices

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A high-power 626 nm diode laser system for Beryllium ion trapping

H. Ball, M. W. Lee, S. D. Gensemer, and M. J. Biercuk

Rev. Sci. Instrum. 84, 063107 (2013); http://dx.doi.org/10.1063/1.4811093 (6 pages)

Online Publication Date: 19 June 2013

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We describe a high-power, frequency-tunable, external cavity diode laser system near 626 nm useful for laser cooling of trapped ⁹Be⁺ ions. A commercial single-mode laser diode with rated power output of 170 mW at 635 nm is cooled to ≈−31°C, and a single longitudinal mode is selected via the Littrow configuration. In our setup, involving two stages of thermoelectric cooling, we are able to obtain ≈130 mW near 626 nm, sufficient for efficient frequency doubling to the required Doppler cooling wavelengths near 313 nm in ionized Beryllium. In order to improve nonlinear frequency conversion efficiency, we achieve larger useful power via injection locking of a slave laser. In this way the entirety of the slave output power is available for frequency doubling, while analysis may be performed on the master output. We believe that this simple laser system addresses a key need in the ion trapping community and dramatically reduces the cost and complexity associated with Beryllium ion trapping experiments.

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42.50.Wk	Mechanical effects of light on material media, microstructures and particles
42.55.Px	Semiconductor lasers; laser diodes
42.60.Da	Resonators, cavities, amplifiers, arrays, and rings
42.60.Fc	Modulation, tuning, and mode locking
42.65.Ky	Frequency conversion; harmonic generation, including higher-order harmonic generation

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Field-programmable gate array based arbitrary signal generator and oscilloscope for use in slow light and storage of light experiments

Stanko N. Nikolić, Viktor Batić, Bratimir Panić, and Branislav M. Jelenković

Rev. Sci. Instrum. 84, 063108 (2013); http://dx.doi.org/10.1063/1.4811147 (9 pages)

Online Publication Date: 19 June 2013

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We present a field-programmable gate array (FPGA) based device that simultaneously generates two arbitrary analog voltage signals with the maximum sample rate of 1.25 MHz and acquires two analog voltage signals with the maximum sample rate of 2.5 MHz. All signals are synchronized with internal FPGA clock. The personal computer application developed for controlling and communicating with FPGA chip provides the shaping of the output signals by mathematical expressions and real-time monitoring of the input signals. The main advantages of FPGA based digital-to-analog and analog-to-digital cards are high speed, rapid reconfigurability, friendly user interface, and low cost. We use this module in slow light and storage of light experiments performed in Rb buffer gas cell.

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42.65.Re	Ultrafast processes; optical pulse generation and pulse compression
42.79.Vb	Optical storage systems, optical disks
84.30.Sk	Pulse and digital circuits
07.07.Hj	Display and recording equipment, oscilloscopes, TV cameras, etc.

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Littrow angle based autocollimation method for precision online monitoring three-dimensional angular drifts of chirped-pulse compression-gratings

Zhaoyang Li, Tao Wang, Guang Xu, Dawei Li, Lei Chen, and Yaping Dai

Rev. Sci. Instrum. 84, 063109 (2013); http://dx.doi.org/10.1063/1.4811148 (7 pages)

Online Publication Date: 19 June 2013

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A simple optical method for online precisely monitoring three-dimensional (3D) angular drifts of chirped-pulse compression-gratings in chirped-pulse amplification (CPA) lasers is proposed. Monitoring objects include all dimensional angular drifts of a grating, especially the grating groove in-plane-rotation. Monitoring contents contain direction and amount. And monitoring results are obtained by detecting the direction and the amount of 2D relative offsets of three focal spots formed by a ternary monitoring beam line. The theoretical model of the proposed method is set up using a matrix ray-tracing method, and a simplified monitoring equation is concluded based on numerical simulations. And the validity of this method is verified by a simple demonstration experiment. Besides, monitoring error and reliability discussion of the method are presented, as well.

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42.60.Fc	Modulation, tuning, and mode locking
42.65.Re	Ultrafast processes; optical pulse generation and pulse compression
42.79.Dj	Gratings

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Microwave sidebands for laser cooling by direct modulation of a tapered amplifier

J. Mahnke, S. Kulas, I. Geisel, S. Jöllenbeck, W. Ertmer, and C. Klempt

Rev. Sci. Instrum. 84, 063110 (2013); http://dx.doi.org/10.1063/1.4811196 (4 pages)

Online Publication Date: 19 June 2013

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Laser cooling of atoms usually necessitates several laser frequencies. Alkaline atoms, for example, are cooled by two lasers with a frequency difference in the gigahertz range. This gap cannot be closed with simple shifting techniques. Here, we present a method of generating sidebands at 6.6 GHz by modulating the current of a tapered amplifier, which is seeded by an unmodulated master laser. The sidebands enable trapping of 1.1 × 10⁹ ⁸⁷Rb atoms in a chip-based magneto-optical trap. Compared to the direct modulation of the master laser, this method allows for an easy implementation, a fast adjustment over a wide frequency range, and the simultaneous extraction of unmodulated light for manipulation and detection. The low power consumption, small size, and applicability for multiple frequencies benefit a wide range of applications reaching from atom-based mobile sensors to the laser cooling of molecules.

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37.10.-x	Atom, molecule, and ion cooling methods
42.50.Wk	Mechanical effects of light on material media, microstructures and particles
32.60.+i	Zeeman and Stark effects

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Measurement of transmission efficiency for 400 MeV proton beam through collimator at Fermilab MuCool Test Area using Chromox-6 scintillation screen

M. R. Jana, M. Chung, B. Freemire, P. Hanlet, M. Leonova, A. Moretti, M. Palmer, T. Schwarz, A. Tollestrup, Y. Torun, and K. Yonehara

Rev. Sci. Instrum. 84, 063301 (2013); http://dx.doi.org/10.1063/1.4808275 (12 pages)

Online Publication Date: 7 June 2013

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The MuCool Test Area (MTA) at Fermilab is a facility to develop the technology required for ionization cooling for a future Muon Collider and/or Neutrino Factory. As part of this research program, feasibility studies of various types of RF cavities in a high magnetic field environment are in progress. As a unique approach, we have tested a RF cavity filled with a high pressure hydrogen gas with a 400 MeV proton beam in an external magnetic field (B = 3 T). Quantitative information about the number of protons passing through this cavity is an essential requirement of the beam test. The MTA is a flammable gas (hydrogen) hazard zone. Due to safety reasons, no active (energized) beam diagnostic instrument can be used. Moreover, when the magnetic field is on, current transformers (toroids) used for beam intensity measurements do not work due to the saturation of the ferrite material of the transformer. Based on these requirements, we have developed a passive beam diagnostic instrumentation using a combination of a Chromox-6 scintillation screen and CCD camera. This paper describes details of the beam profile and position obtained from the CCD image with B = 0 T and B = 3 T, and for high and low intensity proton beams. A comparison is made with beam size obtained from multi-wires detector. Beam transmission efficiency through a collimator with a 4 mm diameter hole is measured by the toroids and CCD image of the scintillation screen. Results show that the transmission efficiency estimated from the CCD image is consistent with the toroid measurement, which enables us to monitor the beam transmission efficiency even in a high magnetic field environment.

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29.27.Fh	Beam characteristics
29.40.Mc	Scintillation detectors
41.85.Si	Particle beam collimators, monochromators

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Electron bunch energy and phase feed-forward stabilization system for the Mark V RF-linac free-electron laser

M. R. Hadmack, B. T. Jacobson, J. M. D. Kowalczyk, B. R. Lienert, J. M. J. Madey, and E. B. Szarmes

Rev. Sci. Instrum. 84, 063302 (2013); http://dx.doi.org/10.1063/1.4809938 (7 pages)

Online Publication Date: 11 June 2013

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An amplitude and phase compensation system has been developed and tested at the University of Hawai‘i for the optimization of the RF drive system to the Mark V free-electron laser. Temporal uniformity of the RF drive is essential to the generation of an electron beam suitable for optimal free-electron laser performance and the operation of an inverse Compton scattering x-ray source. The design of the RF measurement and compensation system is described in detail and the results of RF phase compensation are presented. Performance of the free-electron laser was evaluated by comparing the measured effects of phase compensation with the results of a computer simulation. Finally, preliminary results are presented for the effects of amplitude compensation on the performance of the complete system.

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29.27.Eg	Beam handling; beam transport
29.20.Ej	Linear accelerators
41.60.Cr	Free-electron lasers
07.85.Fv	X- and γ-ray sources, mirrors, gratings, and detectors

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Orientating layers with adjustable pretilt angles for liquid crystals deposited by a linear atmospheric pressure plasma source

Shih-Jie Jian, Chwung-Shan Kou, Jennchang Hwang, Chein-Dhau Lee, and Wei-Cheng Lin

Rev. Sci. Instrum. 84, 063501 (2013); http://dx.doi.org/10.1063/1.4807695 (7 pages)

Online Publication Date: 5 June 2013

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A method for controlling the pretilt angles of liquid crystals (LC) was developed. Hexamethyldisiloxane polymer films were first deposited on indium tin oxide coated glass plates using a linear atmospheric pressure plasma source. The films were subsequently treated with the rubbing method for LC alignment. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy measurements were used to characterize the film composition, which could be varied to control the surface energy by adjusting the monomer feed rate and input power. The results of LC alignment experiments showed that the pretilt angle continuously increased from 0° to 90° with decreasing film surface energy.

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61.30.-v	Liquid crystals
78.30.Jw	Organic compounds, polymers
78.66.Qn	Polymers; organic compounds
79.60.Fr	Polymers; organic compounds
81.15.Jj	Ion and electron beam-assisted deposition; ion plating
68.55.am	Polymers and organics

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In situ “artificial plasma” calibration of tokamak magnetic sensors

D. Shiraki, J. P. Levesque, J. Bialek, P. J. Byrne, B. A. DeBono, M. E. Mauel, D. A. Maurer, G. A. Navratil, T. S. Pedersen, and N. Rath

Rev. Sci. Instrum. 84, 063502 (2013); http://dx.doi.org/10.1063/1.4808366 (9 pages)

Online Publication Date: 7 June 2013

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A unique in situ calibration technique has been used to spatially calibrate and characterize the extensive new magnetic diagnostic set and close-fitting conducting wall of the High Beta Tokamak-Extended Pulse (HBT-EP) experiment. A new set of 216 Mirnov coils has recently been installed inside the vacuum chamber of the device for high-resolution measurements of magnetohydrodynamic phenomena including the effects of eddy currents in the nearby conducting wall. The spatial positions of these sensors are calibrated by energizing several large in situ calibration coils in turn, and using measurements of the magnetic fields produced by the various coils to solve for each sensor's position. Since the calibration coils are built near the nominal location of the plasma current centroid, the technique is referred to as an “artificial plasma” calibration. The fitting procedure for the sensor positions is described, and results of the spatial calibration are compared with those based on metrology. The time response of the sensors is compared with the evolution of the artificial plasma current to deduce the eddy current contribution to each signal. This is compared with simulations using the VALEN electromagnetic code, and the modeled copper thickness profiles of the HBT-EP conducting wall are adjusted to better match experimental measurements of the eddy current decay. Finally, the multiple coils of the artificial plasma system are also used to directly calibrate a non-uniformly wound Fourier Rogowski coil on HBT-EP.

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52.70.Ds	Electric and magnetic measurements
06.20.fb	Standards and calibration
07.07.Df	Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
07.55.-w	Magnetic instruments and components

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Palm top plasma focus device as a portable pulsed neutron source

R. K. Rout, Ram Niranjan, P. Mishra, R. Srivastava, A. M. Rawool, T. C. Kaushik, and Satish C. Gupta

Rev. Sci. Instrum. 84, 063503 (2013); http://dx.doi.org/10.1063/1.4808309 (5 pages)

Online Publication Date: 10 June 2013

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Development of a palm top plasma focus device generating (5.2 ± 0.8) × 10⁴ neutrons/pulse into 4π steradians with a pulse width of 15 ± 3 ns is reported for the first time. The weight of the system is less than 1.5 kg. The system comprises a compact capacitor bank, a triggered open air spark gap switch, and a sealed type miniature plasma focus tube. The setup is around 14 cm in diameter and 12.5 cm in length. The energy driver for the unit is a capacitor bank of four cylindrical commercially available electrolytic capacitors. Each capacitor is of 2 μF capacity, 4.5 cm in diameter, and 9.8 cm in length. The cost of each capacitor is less than US$ 10. The internal diameter and the effective length of the plasma focus unit are 2.9 cm and 5 cm, respectively. A DC to DC converter power supply powered by two rechargeable batteries charges the capacitor bank to the desired voltage and also provides a trigger pulse of −15 kV to the spark gap. The maximum energy of operation of the device is 100 J (8 μF, 5 kV, 59 kA) with deuterium gas filling pressure of 3 mbar. The neutrons have also been produced at energy as low as 36 J (3 kV) of operation. The neutron diagnostics are carried out with a bank of ³He detectors and with a plastic scintillator detector. The device is portable, reusable, and can be operated for multiple shots with a single gas filling.

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52.75.Kq	Plasma switches (e.g., spark gaps)
52.80.Mg	Arcs; sparks; lightning; atmospheric electricity
29.25.Dz	Neutron sources
29.40.Mc	Scintillation detectors
52.70.Nc	Particle measurements

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Architecture, implementation, and testing of a multiple-shell gas injection system for high current implosions on the Z accelerator

Mahadevan Krishnan, Kristi Wilson Elliott, Robert E. Madden, P. L. Coleman, John R. Thompson, Alex Bixler, D. C. Lamppa, J. L. McKenney, T. Strizic, D. Johnson, O. Johns, M. P. Vigil, B. Jones, D. J. Ampleford, M. E. Savage, et al.

Rev. Sci. Instrum. 84, 063504 (2013); http://dx.doi.org/10.1063/1.4809511 (19 pages) | Cited 1 time

Online Publication Date: 10 June 2013

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Tests are ongoing to conduct ∼20 MA z-pinch implosions on the Z accelerator at Sandia National Laboratory using Ar, Kr, and D₂ gas puffs as the imploding loads. The relatively high cost of operations on a machine of this scale imposes stringent requirements on the functionality, reliability, and safety of gas puff hardware. Here we describe the development of a prototype gas puff system including the multiple-shell nozzles, electromagnetic drivers for each nozzle's valve, a UV pre-ionizer, and an inductive isolator to isolate the ∼2.4 MV machine voltage pulse present at the gas load from the necessary electrical and fluid connections made to the puff system from outside the Z vacuum chamber. This paper shows how the assembly couples to the overall Z system and presents data taken to validate the functionality of the overall system.

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52.58.Lq	Z-pinches, plasma focus, and other pinch devices
52.80.Qj	Explosions; exploding wires

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Ultra-fast bright field and fluorescence imaging of the dynamics of micrometer-sized objects

Xucai Chen, Jianjun Wang, Michel Versluis, Nico de Jong, and Flordeliza S. Villanueva

Rev. Sci. Instrum. 84, 063701 (2013); http://dx.doi.org/10.1063/1.4809168 (13 pages)

Online Publication Date: 11 June 2013

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multimedia

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High speed imaging has application in a wide area of industry and scientific research. In medical research, high speed imaging has the potential to reveal insight into mechanisms of action of various therapeutic interventions. Examples include ultrasound assisted thrombolysis, drug delivery, and gene therapy. Visual observation of the ultrasound, microbubble, and biological cell interaction may help the understanding of the dynamic behavior of microbubbles and may eventually lead to better design of such delivery systems. We present the development of a high speed bright field and fluorescence imaging system that incorporates external mechanical waves such as ultrasound. Through collaborative design and contract manufacturing, a high speed imaging system has been successfully developed at the University of Pittsburgh Medical Center. We named the system “UPMC Cam,” to refer to the integrated imaging system that includes the multi-frame camera and its unique software control, the customized modular microscope, the customized laser delivery system, its auxiliary ultrasound generator, and the combined ultrasound and optical imaging chamber for in vitro and in vivo observations. This system is capable of imaging microscopic bright field and fluorescence movies at 25 × 10⁶ frames per second for 128 frames, with a frame size of 920 × 616 pixels. Example images of microbubble under ultrasound are shown to demonstrate the potential application of the system.

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43.35.Wa	Biological effects of ultrasound, ultrasonic tomography
43.80.Vj	Acoustical medical instrumentation and measurement techniques
43.58.-e	Acoustical measurements and instrumentation
43.35.-c	Ultrasonics, quantum acoustics, and physical effects of sound
87.63.lt	Laser imaging
87.64.M-	Optical microscopy

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Development of a confocal rheometer for soft and biological materials

S. K. Dutta, A. Mbi, Richard C. Arevalo, and Daniel L. Blair

Rev. Sci. Instrum. 84, 063702 (2013); http://dx.doi.org/10.1063/1.4810015 (7 pages)

Online Publication Date: 13 June 2013

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We discuss the design and operation of a confocal rheometer, formed by integrating an Anton Paar MCR301 stress-controlled rheometer with a Leica SP5 laser scanning confocal microscope. Combining two commercial instruments results in a system which is straightforward to assemble that preserves the performance of each component with virtually no impact on the precision of either device. The instruments are configured so that the microscope can acquire time-resolved, three-dimensional volumes of a sample whose bulk viscoelastic properties are being measured simultaneously. We describe several aspects of the design and, to demonstrate the system's capabilities, present the results of a few common measurements in the study of soft materials.

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07.60.Pb	Conventional optical microscopes
42.79.Ls	Scanners, image intensifiers, and image converters
46.35.+z	Viscoelasticity, plasticity, viscoplasticity
42.70.-a	Optical materials

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Combined synchrotron X-ray tomography and X-ray powder diffraction using a fluorescing metal foil

P. Kappen, B. D. Arhatari, M. B. Luu, E. Balaur, and T. Caradoc-Davies

Rev. Sci. Instrum. 84, 063703 (2013); http://dx.doi.org/10.1063/1.4810011 (7 pages)

Online Publication Date: 14 June 2013

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This study realizes the concept of simultaneous micro-X-ray computed tomography and X-ray powder diffraction using a synchrotron beamline. A thin zinc metal foil was placed in the primary, monochromatic synchrotron beam to generate a divergent wave to propagate through the samples of interest onto a CCD detector for tomographic imaging, thus removing the need for large beam illumination and high spatial resolution detection. Both low density materials (kapton tubing and a piece of plant) and higher density materials (Egyptian faience) were investigated, and elemental contrast was explored for the example of Cu and Ni meshes. The viability of parallel powder diffraction using the direct beam transmitted through the foil was demonstrated. The outcomes of this study enable further development of the technique towards in situ tomography/diffraction studies combining micrometer and crystallographic length scales, and towards elemental contrast imaging and reconstruction methods using well defined fluorescence outputs from combinations of known fluorescence targets (elements).

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87.57.Q-	Computed tomography
06.30.Bp	Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
07.85.-m	X- and γ-ray instruments
42.79.Pw	Imaging detectors and sensors
29.20.dk	Synchrotrons
61.05.C-	X-ray diffraction and scattering

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Use of a multichannel collimator for structural investigation of low-Z dense liquids in a diamond anvil cell: Validation on fluid H₂ up to 5 GPa

Gunnar Weck, Gaston Garbarino, Sandra Ninet, Dylan Spaulding, Frederic Datchi, Paul Loubeyre, and Mohamed Mezouar

Rev. Sci. Instrum. 84, 063901 (2013); http://dx.doi.org/10.1063/1.4807753 (8 pages)

Online Publication Date: 4 June 2013

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We report the first application of a multichannel collimator (MCC) to perform quantitative structure factor measurements of dense low-Z fluids in a diamond anvil cell (DAC) using synchrotron x-ray diffraction. The MCC design, initially developed for the Paris-Edinburgh large volume press geometry, has been modified for use with diamond anvil cells. A good selectivity of the diffracted signal of the dense fluid sample is obtained due to a large rejection of the Compton diffusion from the diamond anvils. The signal to background ratio is significantly improved. We modify previously developed analytical techniques for quantitative measurement of the structure factor of fluids in DACs [J. H. Eggert, G. Weck, P. Loubeyre, and M. Mezouar, Phys. Rev. B 65, 174105 (2002)10.1103/PhysRevB.65.174105] to account for the contribution of the MCC. We present experimental results on liquids argon and hydrogen at 296 K to validate our method and test its limits, respectively.

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07.85.Qe

Synchrotron radiation instrumentation

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System of laser pump and synchrotron radiation probe microdiffraction to investigate optical recording process

Nobuhiro Yasuda, Yoshimitsu Fukuyama, Shigeru Kimura, Kiminori Ito, Yoshihito Tanaka, Hitoshi Osawa, Toshiyuki Matsunaga, Rie Kojima, Kazuya Hisada, Akio Tsuchino, Masahiro Birukawa, Noboru Yamada, Koji Sekiguchi, Kazuhiko Fujiie, Osamu Kawakubo, et al.

Rev. Sci. Instrum. 84, 063902 (2013); http://dx.doi.org/10.1063/1.4807858 (5 pages)

Online Publication Date: 4 June 2013

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We have developed a system of laser-pump and synchrotron radiation probe microdiffraction to investigate the phase-change process on a nanosecond time scale of Ge₂Sb₂Te₅ film embedded in multi-layer structures, which corresponds to real optical recording media. The measurements were achieved by combining (i) the pump-laser system with a pulse width of 300 ps, (ii) a highly brilliant focused microbeam with wide peak-energy width (ΔE/E ∼ 2%) made by focusing helical undulator radiation without monochromatization, and (iii) a precise sample rotation stage to make repetitive measurements. We successfully detected a very weak time-resolved diffraction signal by using this system from 100-nm-thick Ge₂Sb₂Te₅ phase-change layers. This enabled us to find the dependence of the crystal-amorphous phase change process of the Ge₂Sb₂Te₅ layers on laser power.

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42.79.Vb	Optical storage systems, optical disks
61.80.Ba	Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.82.-d	Radiation effects on specific materials
64.70.K-	Solid-solid transitions
42.70.Gi	Light-sensitive materials

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High-pressure resistivity technique for quasi-hydrostatic compression experiments

C. R. Rotundu, T. Ćuk, R. L. Greene, Z.-X. Shen, Russell J. Hemley, and V. V. Struzhkin

Rev. Sci. Instrum. 84, 063903 (2013); http://dx.doi.org/10.1063/1.4809025 (4 pages)

Online Publication Date: 10 June 2013

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Diamond anvil cell techniques are now well established and powerful methods for measuring materials properties to very high pressure. However, high pressure resistivity measurements are challenging because the electrical contacts attached to the sample have to survive to extreme stress conditions. Until recently, experiments in a diamond anvil cell were mostly limited to non-hydrostatic or quasi-hydrostatic pressure media other than inert gases. We present here a solution to the problem by using focused ion beam ultrathin lithography for a diamond anvil cell loaded with inert gas (Ne) and show typical resistivity data. These ultrathin leads are deposited on the culet of the diamond and are attaching the sample to the anvil mechanically, therefore allowing for measurements in hydrostatic or nearly hydrostatic conditions of pressure using noble gases like Ne or He as pressure transmitting media.

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82.80.-d	Chemical analysis and related physical methods of analysis
85.40.Hp	Lithography, masks and pattern transfer
84.37.+q	Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)

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Design and operation of a rotating drum radio frequency plasma reactor for the modification of free nanoparticles

Jeffrey C. Shearer and Ellen R. Fisher

Rev. Sci. Instrum. 84, 063904 (2013); http://dx.doi.org/10.1063/1.4811138 (8 pages)

Online Publication Date: 19 June 2013

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A rotating drum rf plasma reactor was designed to functionalize the surface of nanoparticles and other unusually shaped substrates through plasma polymerization and surface modification. This proof-of-concept reactor design utilizes plasma polymerized allyl alcohol to add OH functionality to Fe₂O₃ nanoparticles. The reactor design is adaptable to current plasma hardware, eliminating the need for an independent reactor setup. Plasma polymerization performed on Si wafers, Fe₂O₃ nanoparticles supported on Si wafers, and freely rotating Fe₂O₃ nanoparticles demonstrated the utility of the reactor for a multitude of processes. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were used to characterize the surface of the substrates prior to and after plasma deposition, and scanning electron microscopy was used to verify that no extensive change in the size or shape of the nanoparticles occurred because of the rotating motion of the reactor. The reactor design was also extended to a non-depositing NH₃ plasma modification system to demonstrate the reactor design is effective for multiple plasma processes.

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52.77.Dq	Plasma-based ion implantation and deposition
52.80.Pi	High-frequency and RF discharges
79.60.Fr	Polymers; organic compounds
82.33.Xj	Plasma reactions (including flowing afterglow and electric discharges)
82.35.Np	Nanoparticles in polymers
82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
52.30.-q	Plasma dynamics and flow

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A portable transfer chamber for electrochemical measurements on electrodes prepared in ultra-high vacuum

M. El-Jawad, J.-L. Chemin, B. Gilles, and F. Maillard

Rev. Sci. Instrum. 84, 064101 (2013); http://dx.doi.org/10.1063/1.4809936 (6 pages)

Online Publication Date: 12 June 2013

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This paper describes a versatile, light weight, and portable chamber dedicated to the transfer of electrodes from ultra-high vacuum (UHV) to atmospheric pressure and the liquid phase. This chamber can be connected to a liquid-phase reaction cell to perform electrochemical measurements and transfer back the electrode to the UHV environment. The experimental set-up can also be turned in order to make the electrode the bottom of the electrochemical cell. The validity and the efficiency of the experimental set-up were tested with a Pt(111) surface that provides unique electrochemical features in acidic sulphate-containing solution. This transfer chamber concept provides the surface science community with a new and versatile tool, complementary to existing systems, which allows fast electrolyte purging or electrochemical measurements under well-controlled mass transport conditions.

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07.30.Dz	Vacuum gauges
82.45.Gj	Electrolytes
82.45.Fk	Electrodes

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Improvement in the modelling of a half-wave Cockroft-Walton voltage multiplier

Christian G. H. Maennel

Rev. Sci. Instrum. 84, 064701 (2013); http://dx.doi.org/10.1063/1.4807703 (5 pages)

Online Publication Date: 5 June 2013

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Formulae giving the voltage drop of a Cockroft-Walton voltage multiplier are derived using a thorough analysis of the circuit. They differ from standard formulae found in the literature. We show that these new analytical expressions give improved results compared to both numerical simulations and experimental data.

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84.30.-r	Electronic circuits
02.60.-x	Numerical approximation and analysis

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Volume 84, Issue 6 (partial)

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