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Feb 2013

Volume 84, Issue 2, Articles (02xxxx)

Issue Cover Spotlight Figure

Rev. Sci. Instrum. 84, 021101 (2013); http://dx.doi.org/10.1063/1.4789314 (14 pages)

Alexey Goncharov

Typical permanent magnet electrostatic plasma lens, characteristically about 15 cm long and 10 cm inner diameter. The magnets are shown in black between grey spacers. A set of cylindrical ring electrodes are located within the magnetic field region, with field lines connecting ring electrode pairs symmetrically about the lens midplane.

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Invited Review Article: The electrostatic plasma lens

Alexey Goncharov

Rev. Sci. Instrum. 84, 021101 (2013); http://dx.doi.org/10.1063/1.4789314 (14 pages)

Online Publication Date: 5 February 2013

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The fundamental principles, experimental results, and potential applications of the electrostatic plasma lens for focusing and manipulating high-current, energetic, heavy ion beams are reviewed. First described almost 50 years ago, this optical beam device provides space charge neutralization of the ion beam within the lens volume, and thus provides an effective and unique tool for focusing high current beams where a high degree of neutralization is essential to prevent beam blow-up. Short and long lenses have been explored, and a lens in which the magnetic field is provided by rare-earth permanent magnets has been demonstrated. Applications include the use of this kind of optical tool for laboratory ion beam manipulation, high dose ion implantation, heavy ion accelerator injection, in heavy ion fusion, and other high technology.
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52.77.-j Plasma applications
52.40.Mj Particle beam interactions in plasmas
41.85.Ne Electrostatic lenses, septa
41.75.Ak Positive-ion beams
41.75.Cn Negative-ion beams
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Preface to Special Topic: Intense terahertz sources for time-resolved studies of matter

Haidan Wen, Kwang-Je Kim, Alexander Zholents, John Byrd, and Andrea Cavalleri

Rev. Sci. Instrum. 84, 022501 (2013); http://dx.doi.org/10.1063/1.4790426 (1 page)

Online Publication Date: 22 February 2013

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Abstract Unavailable
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84.40.-x Radiowave and microwave (including millimeter wave) technology

Intense terahertz pulses from SLAC electron beams using coherent transition radiation

Ziran Wu, Alan S. Fisher, John Goodfellow, Matthias Fuchs, Dan Daranciang, Mark Hogan, Henrik Loos, and Aaron Lindenberg

Rev. Sci. Instrum. 84, 022701 (2013); http://dx.doi.org/10.1063/1.4790427 (10 pages) | Cited 2 times

Online Publication Date: 22 February 2013

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SLAC has two electron accelerators, the Linac Coherent Light Source (LCLS) and the Facility for Advanced Accelerator Experimental Tests (FACET), providing high-charge, high-peak-current, femtosecond electron bunches. These characteristics are ideal for generating intense broadband terahertz (THz) pulses via coherent transition radiation. For LCLS and FACET respectively, the THz pulse duration is typically 20 and 80 fs RMS and can be tuned via the electron bunch duration; emission spectra span 3–30 THz and 0.5 THz–5 THz; and the energy in a quasi-half-cycle THz pulse is 0.2 and 0.6 mJ. The peak electric field at a THz focus has reached 4.4 GV/m (0.44 V/Å) at LCLS. This paper presents measurements of the terahertz pulses and preliminary observations of nonlinear materials response.
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41.75.Fr Electron and positron beams
41.75.Ht Relativistic electron and positron beams
29.20.-c Accelerators
29.27.Eg Beam handling; beam transport

The TeraFERMI terahertz source at the seeded FERMI free-electron-laser facility

A. Perucchi, S. Di Mitri, G. Penco, E. Allaria, and S. Lupi

Rev. Sci. Instrum. 84, 022702 (2013); http://dx.doi.org/10.1063/1.4790428 (8 pages)

Online Publication Date: 22 February 2013

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We describe the project for the construction of a terahertz (THz) beamline to be called TeraFERMI at the seeded FERMI free electron laser (FEL) facility in Trieste, Italy. We discuss topics as the underlying scientific case, the choice of the source, the expected performance, and THz beam propagation. Through electron beam dynamics simulations we show that the installation of the THz source in the beam dump section provides a new approach for compressing the electron bunch length without affecting FEL operation. Thanks to this further compression of the FEL electron bunch, the TeraFERMI facility is expected to provide THz pulses with energies up to the mJ range during normal FEL operation.
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41.60.Cr Free-electron lasers
41.75.Fr Electron and positron beams

Characterization of the THz radiation source at the Frascati linear accelerator

E. Chiadroni, M. Bellaveglia, P. Calvani, M. Castellano, L. Catani, A. Cianchi, G. Di Pirro, M. Ferrario, G. Gatti, O. Limaj, S. Lupi, B. Marchetti, A. Mostacci, E. Pace, L. Palumbo, et al.

Rev. Sci. Instrum. 84, 022703 (2013); http://dx.doi.org/10.1063/1.4790429 (12 pages)

Online Publication Date: 22 February 2013

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The linac driven coherent THz radiation source at the SPARC-LAB test facility is able to deliver broadband THz pulses with femtosecond shaping. In addition, high peak power, narrow spectral bandwidth THz radiation can be also generated, taking advantage of advanced electron beam manipulation techniques, able to generate an adjustable train of electron bunches with a sub-picosecond length and with sub-picosecond spacing. The paper reports on the manipulation, characterization, and transport of the electron beam in the bending line transporting the beam down to the THz station, where different coherent transition radiation spectra have been measured and studied with the aim to optimize the THz radiation performances.
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84.40.-x Radiowave and microwave (including millimeter wave) technology

Generating ultrabroadband terahertz radiation based on the under-compression mode of velocity bunching

D. Wang, L. X. Yan, Y. C. Du, J. F. Hua, Q. Du, H. J. Qian, X. H. Lu, W. H. Huang, H. B. Chen, and C. X. Tang

Rev. Sci. Instrum. 84, 022704 (2013); http://dx.doi.org/10.1063/1.4790430 (5 pages)

Online Publication Date: 22 February 2013

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We propose and analyze a scheme to generate enhanced ultrabroadband terahertz (THz) radiation through coherent transition radiation emitted by ultrashort electron beams based on a 10.5 m beamline at Tsinghua University. The proposed scheme involves the initial compression of the electron beam with a few hundred pC charges using a velocity bunching scheme (i.e., RF compression) in an under-compression mode instead of the usual critical-compression mode in order to maintain a positive energy chirp at the exit of the traveling wave accelerator. After a long drift segment, the particles in the tail catch up with the bunch head. More than 80% of the particles are distributed in a spike with an rms length less than 20 fs. Such beams correspond to an ultrabroadband coherent transition radiation (CTR) spectrum of 0.1 THz to 25 THz, with the single-pulse THz radiation energy of up to 50 μJ. The principle of CTR and under-compression mode of velocity bunching are introduced in this paper. And the ASTRA simulation parameters and the stability of the system are also discussed.
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41.75.Fr Electron and positron beams

FLUTE: A versatile linac-based THz source

M. J. Nasse, M. Schuh, S. Naknaimueang, M. Schwarz, A. Plech, Y.-L. Mathis, R. Rossmanith, P. Wesolowski, E. Huttel, M. Schmelling, and A.-S. Müller

Rev. Sci. Instrum. 84, 022705 (2013); http://dx.doi.org/10.1063/1.4790431 (4 pages)

Online Publication Date: 22 February 2013

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A new compact versatile linear accelerator named FLUTE is currently being designed at the Karlsruhe Institute of Technology. This paper presents the status of this 42 MeV machine. It will be used to generate strong (several 100 MV/m) ultra-short (∼1 ps) THz pulses (up to ∼4–25 THz) for photon science experiments, as well as to conduct a variety of accelerator studies. The latter range from comparing different coherent THz radiation generation schemes to compressing electron bunches and studying the electron beam stability. The bunch charge will cover a wide range (∼100 pC–3 nC). Later we plan to also produce ultra-short x-ray pulses from the electron bunches, which, for example, could then be combined for THz pump–x-ray probe experiments.
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29.20.Ej Linear accelerators
29.27.Eg Beam handling; beam transport
61.82.-d Radiation effects on specific materials
89.20.Kk Engineering

High power terahertz radiation source based on electron beam wakefields

Sergey Antipov, Chunguang Jing, Paul Schoessow, Alexei Kanareykin, Vitaly Yakimenko, Alexander Zholents, and Wei Gai

Rev. Sci. Instrum. 84, 022706 (2013); http://dx.doi.org/10.1063/1.4790432 (4 pages)

Online Publication Date: 22 February 2013

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A table top device for producing high peak power (tens of megawatts to a gigawatt) T-ray beams is described. An electron beam with a rectangular longitudinal profile is produced out of a photoinjector via stacking of the laser pulses. The beam is also run off-crest of the photoinjector rf to develop an energy chirp. After passing through a dielectric loaded waveguide, the beam's energy becomes modulated by its self-wake. In a chicane beamline following the dielectric energy-bunching section this energy modulation is converted to a density modulation—a bunch train. The density modulated beam can be sent through a power extraction section, like a dielectric loaded accelerating structure, or simply can intercept a foil target, producing THz radiation of various bandwidths and power levels.
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84.40.Az Waveguides, transmission lines, striplines
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
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back to top Optics; Atoms and Molecules; Spectroscopy; Photon Detectors

Sensitivity calibration of an imaging extreme ultraviolet spectrometer-detector system for determining the efficiency of broadband extreme ultraviolet sources

S. Fuchs, C. Rödel, M. Krebs, S. Hädrich, J. Bierbach, A. E. Paz, S. Kuschel, M. Wünsche, V. Hilbert, U. Zastrau, E. Förster, J. Limpert, and G. G. Paulus

Rev. Sci. Instrum. 84, 023101 (2013); http://dx.doi.org/10.1063/1.4788732 (5 pages)

Online Publication Date: 4 February 2013

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We report on the absolute sensitivity calibration of an extreme ultraviolet (XUV) spectrometer system that is frequently employed to study emission from short-pulse laser experiments. The XUV spectrometer, consisting of a toroidal mirror and a transmission grating, was characterized at a synchrotron source in respect of the ratio of the detected to the incident photon flux at photon energies ranging from 15.5 eV to 99 eV. The absolute calibration allows the determination of the XUV photon number emitted by laser-based XUV sources, e.g., high-harmonic generation from plasma surfaces or in gaseous media. We have demonstrated high-harmonic generation in gases and plasma surfaces providing 2.3 μW and μJ per harmonic using the respective generation mechanisms.
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07.60.Rd Visible and ultraviolet spectrometers
42.72.-g Optical sources and standards
42.79.Bh Lenses, prisms and mirrors
42.79.Dj Gratings
42.79.Pw Imaging detectors and sensors
06.20.fb Standards and calibration

A new high intensity and short-pulse molecular beam valve

B. Yan, P. F. H. Claus, B. G. M. van Oorschot, L. Gerritsen, A. T. J. B. Eppink, S. Y. T. van de Meerakker, and D. H. Parker

Rev. Sci. Instrum. 84, 023102 (2013); http://dx.doi.org/10.1063/1.4790176 (8 pages)

Online Publication Date: 6 February 2013

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In this paper, we report on the design and performance of a new home-built pulsed gas valve, which we refer to as the Nijmegen Pulsed Valve (NPV). The main output characteristics include a short pulse width (as short as 20 μs) combined with operating rates up to 30 Hz. The operation principle of the NPV is based on the Lorentz force created by a pulsed current passing through an aluminum strip located within a magnetic field, which opens the nozzle periodically. The amplitude of displacement of the opening mechanism is sufficient to allow the use of nozzles with up to 1.0 mm diameter. To investigate the performance of the valve, several characterizations were performed with different experimental methods. First, a fast ionization gauge was used to measure the beam intensity of the free jet emanating from the NPV. We compare free jets from the NPV with those from several other pulsed valves in current use in our laboratory. Results showed that a high intensity and short pulse-length beam could be generated by the new valve. Second, the NPV was tested in combination with a skimmer, where resonance enhanced multiphoton ionization combined with velocity map imaging was used to show that the NPV was able to produce a pulsed molecular beam with short pulse duration (∼20 μs using 0.1% NO/He at 6 bars) and low rotational temperature (∼1 K using 0.5% NO/Ar at 6 bars). Third, a novel two-point pump-probe method was employed which we label double delay scan. This method allows a full kinematic characterization of the molecular beam, including accurate speed ratios at different temporal positions. It was found that the speed ratio was maximum (S = 50 using 0.1% NO/He at 3 bars) at the peak position of the molecular beam and decreased when it was on the leading or falling edge.
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89.20.Kk Engineering
89.20.Bb Industrial and technological research and development
FREE

A quantum cascade laser absorption spectrometer devoted to the in situ measurement of atmospheric N2O and CH4 emission fluxes

I. Mappé, L. Joly, G. Durry, X. Thomas, T. Decarpenterie, J. Cousin, N. Dumelie, E. Roth, A. Chakir, and P. G. Grillon

Rev. Sci. Instrum. 84, 023103 (2013); http://dx.doi.org/10.1063/1.4790376 (8 pages)

Online Publication Date: 12 February 2013

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This paper describes a Quantum Cascade Laser Absorption Spectrometer, called “QCLAS” that was developed to monitor in situ greenhouse gases like N2O and CH4, at high temporal resolution and with a high accuracy. The design of the laser sensor is reported as well as its performances in terms of precision error and field deployment capabilities. Finally, to demonstrate the efficiency and the robustness of QCLAS and its suitability for gas emission monitoring and for the determination of fluxes, we report the results from a field campaign, that took place in the Wallis and Futuna Islands in 2011, to investigate the impact of environmental intensive pig farming.
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42.55.Px Semiconductor lasers; laser diodes
42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy

A polychromator-type near-infrared spectrometer with a high-sensitivity and high-resolution photodiode array detector for pharmaceutical process monitoring on the millisecond time scale

Kodai Murayama, Takuma Genkawa, Daitaro Ishikawa, Makoto Komiyama, and Yukihiro Ozaki

Rev. Sci. Instrum. 84, 023104 (2013); http://dx.doi.org/10.1063/1.4790413 (8 pages)

Online Publication Date: 13 February 2013

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In the fine chemicals industry, particularly in the pharmaceutical industry, advanced sensing technologies have recently begun being incorporated into the process line in order to improve safety and quality in accordance with process analytical technology. For estimating the quality of powders without preparation during drug formulation, near-infrared (NIR) spectroscopy has been considered the most promising sensing approach. In this study, we have developed a compact polychromator-type NIR spectrometer equipped with a photodiode (PD) array detector. This detector is consisting of 640 InGaAs-PD elements with 20-μm pitch. Some high-specification spectrometers, which use InGaAs-PD with 512 elements, have a wavelength resolution of about 1.56 nm when covering 900–1700 nm range. On the other hand, the newly developed detector, having the PD with one of the world's highest density, enables wavelength resolution of below 1.25 nm. Moreover, thanks to the combination with a highly integrated charge amplifier array circuit, measurement speed of the detector is higher by two orders than that of existing PD array detectors. The developed spectrometer is small (120 mm × 220 mm × 200 mm) and light (6 kg), and it contains various key devices including the high-density and high-sensitivity PD array detector, NIR technology, and spectroscopy technology for a spectroscopic analyzer that has the required detection mechanism and high sensitivity for powder measurement, as well as a high-speed measuring function for blenders. Moreover, we have evaluated the characteristics of the developed NIR spectrometer, and the measurement of powder samples confirmed that it has high functionality.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
82.80.Bg Chromatography
85.60.Dw Photodiodes; phototransistors; photoresistors

Cascaded two-photon spectroscopy of Yb atoms with a transportable effusive atomic beam apparatus

Minsoo Song and Tai Hyun Yoon

Rev. Sci. Instrum. 84, 023105 (2013); http://dx.doi.org/10.1063/1.4790849 (5 pages)

Online Publication Date: 14 February 2013

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We present a transportable effusive atomic beam apparatus for cascaded two-photon spectroscopy of the dipole-forbidden transition (6s2 1S0↔ 6s7s 1S0) of Yb atoms. An ohmic-heating effusive oven is designed to have a reservoir volume of 1.6 cm3 and a high degree of atomic beam collimation angle of 30 mrad. The new atomic beam apparatus allows us to detect the spontaneously cascaded two-photons from the 6s7s1S0 state via the intercombination 6s6p3P1 state with a high signal-to-noise ratio even at the temperature of 340 °C. This is made possible in our apparatus because of the enhanced atomic beam flux and superior detection solid angle.
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37.20.+j Atomic and molecular beam sources and techniques
03.75.Pp Atom lasers
32.80.-t Photoionization and excitation
42.62.Fi Laser spectroscopy

Time-of-flight electron spectrometer for a broad range of kinetic energies

Alexander Kothe, Jan Metje, Martin Wilke, Alexandre Moguilevski, Nicholas Engel, Ruba Al-Obaidi, Clemens Richter, Ronny Golnak, Igor Yu. Kiyan, and Emad F. Aziz

Rev. Sci. Instrum. 84, 023106 (2013); http://dx.doi.org/10.1063/1.4791792 (7 pages)

Online Publication Date: 20 February 2013

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A newly constructed time-of-flight electron spectrometer of the magnetic bottle type is characterized for electron detection in a broad range of kinetic energies. The instrument is designed to measure the energy spectra of electrons generated from liquids excited by strong laser fields and photons in the range of extreme ultra violet and soft X-rays. Argon inner shell electrons were recorded to calibrate the spectrometer and investigate its characteristics, such as energy resolution and collection efficiency. Its energy resolution ΔE/E of 1.6% allows resolving the Ar 2p spin orbit structure at kinetic energies higher than 100 eV. The collection efficiency is determined and compared to that of the spectrometer in its field-free configuration.
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07.81.+a Electron and ion spectrometers
06.20.fb Standards and calibration

Continuously tunable optical multidimensional Fourier-transform spectrometer

P. Dey, J. Paul, J. Bylsma, S. Deminico, and D. Karaiskaj

Rev. Sci. Instrum. 84, 023107 (2013); http://dx.doi.org/10.1063/1.4792378 (7 pages)

Online Publication Date: 21 February 2013

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A multidimensional optical nonlinear spectrometer (MONSTR) is a robust, ultrastable platform consisting of nested and folded Michelson interferometers that can be actively phase stabilized. The MONSTR provides output pulses for nonlinear excitation of materials and phase-stabilized reference pulses for heterodyne detection of the induced signal. This platform generates a square of identical laser pulses that can be adjusted to have arbitrary time delays between them while maintaining phase stability. This arrangement is ideal for performing coherent optical experiments, such as multidimensional Fourier-transform spectroscopy. The present work reports on overcoming some important limitations on the original design of the MONSTR apparatus. One important advantage of the MONSTR is the fact that it is a closed platform, which provides the high stability. Once the optical alignment is performed, it is desirable to maintain the alignment over long periods of time. The previous design of the MONSTR was limited to a narrow spectral range defined by the optical coating of the beam splitters. In order to achieve tunability over a broad spectral range the internal optics needed to be changed. By using broadband coated and wedged beam splitters and compensator plates, combined with modifications of the beam paths, continuous tunability can be achieved from 520 nm to 1100 nm without changing any optics or performing alignment of the internal components of the MONSTR. Furthermore, in order to achieve continuous tunability in the spectral region between 520 nm and 720 nm, crucially important for studies on numerous biological molecules, a single longitudinal mode laser at 488.5 nm was identified and used as a metrology laser. The shorter wavelength of the metrology laser as compared to the usual HeNe laser has also increased the phase stability of the system. Finally, in order to perform experiments in the reflection geometry, a simple method to achieve active phase stabilization between the signal and the reference beams has been developed.
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07.60.Ly Interferometers
07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques

Slab coupled optical fiber sensor calibration

B. Whitaker, J. Noren, S. Chadderdon, W. Wang, R. Forber, R. Selfridge, and S. Schultz

Rev. Sci. Instrum. 84, 023108 (2013); http://dx.doi.org/10.1063/1.4789766 (6 pages) | Cited 1 time

Online Publication Date: 22 February 2013

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This paper presents a method for calibrating slab coupled optical fiber sensors (SCOS). An automated system is presented for selecting the optimal laser wavelength for use in SCOS interrogation. The wavelength calibration technique uses a computer sound card for both the creation of the applied electric field and the signal detection. The method used to determine the ratio between the measured SCOS signal and the applied electric field is also described along with a demonstration of the calibrated SCOS involving measuring the dielectric breakdown of air.
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42.81.Pa Sensors, gyros
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
06.20.fb Standards and calibration
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy

Photoacoustic absorption spectrometer for highly transparent dielectrics with parts-per-million sensitivity

Niklas Waasem, Stephan Fieberg, Janosch Hauser, Gregory Gomes, Daniel Haertle, Frank Kühnemann, and Karsten Buse

Rev. Sci. Instrum. 84, 023109 (2013); http://dx.doi.org/10.1063/1.4792724 (8 pages)

Online Publication Date: 26 February 2013

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A sensitive photoacoustic absorption spectrometer for highly transparent solids has been built and tested. As the light source an optical parametrical oscillator pumped by a nanosecond pulse laser with 10 Hz repetition rate is employed, covering the complete wavelength range from 407 to 2600 nm. A second-harmonic-generation unit extends the range of accessible wavelengths down to 212 nm. A lead-zirconate-titanate piezo transducer, directly coupled to the sample, detects the photoacoustically generated sound waves. Absorption spectra of lithium triborate, lithium niobate, and alpha barium borate crystals with absorption coefficients down to 10−5 cm−1 are presented.
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43.38.Fx Piezoelectric and ferroelectric transducers
84.30.Ng Oscillators, pulse generators, and function generators
back to top Particle Sources, Optics and Acceleration; Particle Detectors

Plasma electron source for the generation of wide-aperture pulsed beam at forevacuum pressures

E. Oks, V. Burdovitsin, A. Medovnik, and Yu. Yushkov

Rev. Sci. Instrum. 84, 023301 (2013); http://dx.doi.org/10.1063/1.4789771 (4 pages)

Online Publication Date: 1 February 2013

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This article reports on design and application of wide-aperture pulsed beam source, based on hollow cathode discharge. The source is intended for electron beam generation in pressure range 2–15 Pa. Multi-aperture extraction system, used in a source, provided beam cross-section uniformity of 10% on diameter 40 mm. The limiting values of the current density, pulse duration, and accelerating voltage are 350 mA/cm2, 250 μs, and 10 kV, respectively. These parameters are sufficient for surface modification of various materials, including non-conducting matters.
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52.50.Dg Plasma sources
52.25.Fi Transport properties
52.80.Hc Glow; corona
41.75.Fr Electron and positron beams

Conceptual design and scaled experimental validation of an actively damped carbon tie rods support system for the stabilization of future particle collider superstructures

C. Collette, D. Tshilumba, L. Fueyo-Rosa, and I. Romanescu

Rev. Sci. Instrum. 84, 023302 (2013); http://dx.doi.org/10.1063/1.4789783 (7 pages)

Online Publication Date: 4 February 2013

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This paper presents a simple solution to increase the stability of the large superstructures supporting the final electromagnets of future linear particle collider. It consists of active carbon fiber tie rods, fixed at one end on the structure and at the other end to the detector through active tendons. In the first part of the paper, the solution has been tested on a finite element model of one half of the CLIC_ILD final focus structure. With a reasonable design, it is shown numerically that the compliance can be decreased by at least a factor 4, i.e., that the structure is 4 times more robust to technical noise at low frequency. Two additional features of the active rods are that they can also actively damp the structural resonances and realign the superstructures. The second part of the paper presents a successful experimental validation of the concept, applied to a scaled test bench, especially designed to contain the same modal characteristics as the full scale superstructure.
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29.20.Ej Linear accelerators
02.70.Dh Finite-element and Galerkin methods

Radio frequency cavity analysis, measurement, and calibration of absolute Dee voltage for K-500 superconducting cyclotron at VECC, Kolkata

Sumit Som, Sudeshna Seth, Aditya Mandal, Saikat Paul, and Anjan Duttagupta

Rev. Sci. Instrum. 84, 023303 (2013); http://dx.doi.org/10.1063/1.4789784 (5 pages)

Online Publication Date: 6 February 2013

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Variable Energy Cyclotron Centre has commissioned a K-500 superconducting cyclotron for various types of nuclear physics experiments. The 3-phase radio-frequency system of superconducting cyclotron has been developed in the frequency range 9–27 MHz with amplitude and phase stability of 100 ppm and ±0.20, respectively. The analysis of the RF cavity has been carried out using 3D Computer Simulation Technology (CST) Microwave Studio code and various RF parameters and accelerating voltages (“Dee” voltage) are calculated from simulation. During the RF system commissioning, measurement of different RF parameters has been done and absolute Dee voltage has been calibrated using a CdTe X-ray detector along with its accessories and known X-ray source. The present paper discusses about the measured data and the simulation result.
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29.20.dg Cyclotrons
29.27.-a Beams in particle accelerators
06.20.fb Standards and calibration

First successful ionization of Lr (Z = 103) by a surface-ionization technique

Tetsuya K. Sato, Nozomi Sato, Masato Asai, Kazuaki Tsukada, Atsushi Toyoshima, Kazuhiro Ooe, Sunao Miyashita, Matthias Schädel, Yusuke Kaneya, Yuichiro Nagame, Akihiko Osa, Shin-ichi Ichikawa, Thierry Stora, and Jens Volker Kratz

Rev. Sci. Instrum. 84, 023304 (2013); http://dx.doi.org/10.1063/1.4789772 (5 pages)

Online Publication Date: 20 February 2013

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We have developed a surface ionization ion-source as part of the JAEA-ISOL (Isotope Separator On-Line) setup, which is coupled to a He/CdI2 gas-jet transport system to determine the first ionization potential of the heaviest actinide lawrencium (Lr, Z = 103). The new ion-source is an improved version of the previous source that provided good ionization efficiencies for lanthanides. An additional filament was newly installed to give better control over its operation. We report, here, on the development of the new gas-jet coupled surface ion-source and on the first successful ionization and mass separation of 27-s 256Lr produced in the 249Cf + 11B reaction.
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34.50.Fa Electronic excitation and ionization of atoms (including beam-foil excitation and ionization)
32.50.+d Fluorescence, phosphorescence (including quenching)

Development of a cold-neutron imaging detector based on thick gaseous electron multiplier

M. Cortesi, R. Zboray, A. Kaestner, and H.-M. Prasser

Rev. Sci. Instrum. 84, 023305 (2013); http://dx.doi.org/10.1063/1.4793225 (7 pages)

Online Publication Date: 26 February 2013

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We present the results of our recent studies on a cold-neutron imaging detector prototype based on THick Gaseous Electron Multiplier (THGEM). The detector consists of a thin Boron layer, for neutron-to-charged particle conversion, coupled to two THGEM electrodes in cascade for charge amplification and a position-sensitive charge-readout anode. The detector operates in Ne/(5%)CF4, at atmospheric pressure, in a stable condition at a gain of around 104. Due to the geometrical structure of the detector elements (THGEM geometry and charge read-out anode), the image of detector active area shows a large inhomogeneity, corrected using a dedicated flat-filed correction algorithm. The prototype provides a detection efficiency of 5% and an effective spatial resolution of the order of 1.3 mm.
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29.40.Gx Tracking and position-sensitive detectors

A new kind of low-inductance transformer type magnetic switch (TTMS) with coaxial cylindrical conductors

Yu Zhang and Jinliang Liu

Rev. Sci. Instrum. 84, 023306 (2013); http://dx.doi.org/10.1063/1.4791926 (8 pages) | Cited 1 time

Online Publication Date: 27 February 2013

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As important devices for voltage boosting and switching, respectively, pulse transformer and magnetic switch are widely used in pulsed power technology. In this paper, a new kind of transformer type magnetic switch (TTMS) with coaxial cylindrical conductors is put forward to combine the functions of voltage boosting and switching in one power device. As a compact combination device of discrete pulse transformer and magnetic switch, the compact TTMS decreases the required volume of magnetic cores in a large scale. The primary windings of the TTMS have a parallel combination structure so that the TTMS which only has 3 turns of secondary windings has a step-up ratio at 1:9. Before the magnetic core saturates, the TTMS has low unsaturated inductances of windings and good pulse response characteristics, so it can be used to substitute the Marx generator to charge the pulse forming line (PFL) at the ranges of several hundred kV and several hundred ns. After the core saturates, the cylindrical conductors can decrease the saturated inductance of the secondary windings of TTMS to a level less than 400 nH. As a result, the proposed TTMS can be used as the boosting transformer and main switch of helical Blumlein PFL to form the quasi-square voltage pulse on the 160 Ω load with a short pulse rise time only at 60 ns.
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84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
85.70.-w Magnetic devices
84.32.Ff Conductors, resistors (including thermistors, varistors, and photoresistors)

Influence of gold coating and interplate voltage on the performance of chevron micro-channel plates for temporally and spatially resolved single particle detection

A. L. Hoendervanger, D. Clément, A. Aspect, C. I. Westbrook, D. Dowek, Y. J. Picard, and D. Boiron

Rev. Sci. Instrum. 84, 023307 (2013); http://dx.doi.org/10.1063/1.4793402 (8 pages)

Online Publication Date: 28 February 2013

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We present a study of two different sets of Micro-Channel Plates used for time and space resolved single particle detection. We investigate the effects of the gold coating and that of introducing an interplate voltage between the spatially separated plates. We find that the gold coating increases the count rate of the detector and the pulse amplitude as previously reported for non-spatially resolved setups. The interplate voltage also increases count rates. In addition, we find that a non-zero interplate voltage improves the spatial accuracy in determining the arrival position of incoming single particles (by ∼20%) while the gold coating has a negative effect (by ∼30%).
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29.40.-n Radiation detectors
42.79.Ls Scanners, image intensifiers, and image converters
85.60.Ha Photomultipliers; phototubes and photocathodes
back to top Nuclear Physics, Fusion and Plasmas

Single exposure three-dimensional imaging of dusty plasma clusters

Peter Hartmann, István Donkó, and Zoltán Donkó

Rev. Sci. Instrum. 84, 023501 (2013); http://dx.doi.org/10.1063/1.4789770 (5 pages)

Online Publication Date: 1 February 2013

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We have worked out the details of a single camera, single exposure method to perform three-dimensional imaging of a finite particle cluster. The procedure is based on the plenoptic imaging principle and utilizes a commercial Lytro light field still camera. We demonstrate the capabilities of our technique on a single layer particle cluster in a dusty plasma, where the camera is aligned and inclined at a small angle to the particle layer. The reconstruction of the third coordinate (depth) is found to be accurate and even shadowing particles can be identified.
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52.27.Lw Dusty or complex plasmas; plasma crystals
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
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