Gold-plated Tungsten Wires Research Articles

Development of a time of flight spectrometer based on position sensitive multi-wire proportional counters for fission fragment mass distribution studies.

Characteristics and performance of a time of flight (TOF) spectrometer developed for performing fission mass distribution studies are presented. The spectrometer contains two TOF arms based on multi-wire proportional counters (MWPCs). Each arm has two MWPCs to form a start-stop detection system for TOF measurements. The start detector has an active area of 4 × 4cm2. The stop detector is a two-dimensional position sensitive MWPC with an active area of 16 × 11cm2. Salient features of the MWPCs are the use of reduced sub-millimeter wire pitches of 0.635 and 0.317mm in the electrodes along with the use of gold plated tungsten wires of diameters 10 and 20 µm. A delay line for position electrodes is prepared using chip inductors and capacitors. Ten different configurations of MWPC were investigated for the start detector, which involved the use of three and four electrode geometries, use of different wire pitches, and use of aluminized mylar for timing electrodes. Performance results close to micro-channel plate detectors have been observed with some designs of MWPC, displaying rise times better than 2ns with an estimated inherent time resolution of ∼100ps FWHM. A position resolution of ∼1mm (FWHM) has been observed. Design features of the MWPCs and their test performance results are described in this article.

High-speed imaging of transition from fluid breakup to phase explosion in electric explosion of tungsten wires in air

High-speed visible imaging of sub-microsecond electric explosion of wires at the low specific energy deposition threshold reveals three distinct modes of wire failure as capacitor charge voltage and energy deposition are increased. For 100 μm diameter gold-plated tungsten wires of 2 cm length, deposited energies of 1.9 eV/atom produce a liquid column that undergoes hydrodynamic breakup into droplets with radii of the order of wire diameter on timescales of 200 μs. Instability growth, column breakup, and droplet coalescence follow classical Rayleigh–Plateau predictions for instability of the viscous fluid column. Above a deposited energy of 3.2 eV/atom, wires are seen to abruptly transition to an expanding mixture of micrometer scale liquid-droplets and vapor within one frame (less than 3.33 μs), which has been termed “phase explosion” in the literature. Between these two limits, at a deposited energy of 2.5 eV/atom, the wire radius remains unchanged for the first 10 μs before the onset of a rapid expansion and disintegration that resembles homogenous nucleation of mechanically unstable bubbles. Thermodynamic calculations are presented, which separate cases by temperature obtained during heating: below the boiling point, near the boiling point, and exceeding the boiling point.

Performance study of a novel sampling TPC prototype detector based on THGEM

Time projection chamber (TPC) with micropattern gaseous detectors (MPGDs) as readout has been one of the research hotspots in recent years. MPGD-based TPC has been applying to many experiments due to its high spatial and energy resolutions in 3D track measurement. A novel sampling TPC detector based on thick gaseous electron multiplier (THGEM) was developed to measure the low-energy electron tracks online from 0.1 to 50 MeV with a 100 $$\upmu \hbox {m}$$ spatial resolution in a vacuum tank. The tracks will be extrapolated to determine the hit positions on a target about 200 mm behind the TPC. A new type of self-developed THGEM detector was chosen as the TPC readout unit. The field cage has two $$50 \times 50\,\hbox {mm}^2$$ windows welded by Gold-plated tungsten wires for low-energy electrons passing through. The front-end electronics was designed with a self-developed application specific integrated circuit chip, i.e., CASA-GEM. Seven columns of readout pads were used to equidistantly sample the electron tracks in a length of 75 mm. Each column has 72 pads of $$0.56 \times 0.56 \,\hbox {mm}^2$$ and two additional strips along each column for drift time measurement. Both Geant4 and Garfield++ were chosen to simulate and optimize the detector, such as the penetration efficiency, electric field in field cage and operating gas pressure. The design and the preliminary performances of the TPC detector were verified by beam test and $$\beta $$ source test. A drift velocity of $$3.415 \pm 0.103\,\hbox {cm}/\upmu \hbox {s}$$ was measured at 125 V/cm in $$\hbox {Ar} + \hbox {iC}_4\hbox {H}_{10} ~(97:3)$$ for $$\pi ^-$$ . The electron detection efficiency is about 88% for $$\beta $$ source. And the gain of the double THGEM reached more than $$1.0 \times 10^4$$ .

Development of a Wire Reference Electrode for Lithium All-Solid-State Batteries with Polymer Electrolyte: FEM Simulation and Experiment

Electrochemical impedance spectroscopy (EIS) is a powerful technique to study interface kinetics in lithium ion batteries. In order to separate the contributions of the working and counter electrode, a reference electrode (RE) is crucial. However, size and shape of the RE strongly influence the quality of the measurement data. In this study we define two criteria that enable the theoretical quality assessment of a wire-shaped RE as a function of its diameter. With help of a simplified Newman-type battery model we show that small wire diameters are essential in order to obtain meaningful EIS data, in particular when using polymer electrolytes, which have comparably low ionic conductivity. Therefore, a gold plated tungsten wire with 10 μm diameter is chosen as preferred RE. It is placed between two layers of electrolyte and lithiated before use to ensure a long-term stable reference potential. Using this setup, artifact-free EIS spectra are obtained for lithium/lithium and lithium/LFP cells with polymer electrolyte. Finally, two applications are shown for which a RE is indispensable: (I) the symmetry of anodic and cathodic lithium dissolution and deposition kinetics is characterized; (II) the growth of the anode and cathode impedance of a lithium/LFP cell during cycling is monitored.

Simultaneous detection of E. coli K12 and S. aureus Using a Continuous Flow Multijunction Biosensor.

Rapid detection and identification of potentially harmful bacteria is ideal for food manufacturers to prevent foodborne illness outbreaks. Continuous monitoring method of foodborne pathogens levels and trends in food gives real-time results. Therefore, the objectives of this study were to fabricate and characterize the continuous flow multijunction biosensor for simultaneous detection of Escherichia coli K12 and Staphylococcus aureus. Junction biosensors were fabricated using gold plated tungsten wires coated with polyethylenimine and single walled carbon nanotubes. Each junction was functionalized with streptavidin and biotinylated antibodies specific to E. coli K12 and S. aureus. Then, single or 2 biosensors for each targeted analyte were connected to tubing, perpendicular to the flow direction. Pure serial diluted samples of E. coli K12 and S. aureus and microbial cocktail samples were continuously pumped at a 0.0167 mL/s into the detection zone. Changes in the electric current by biorecognition reactions between antibody and antigens were calculated. The developed junction sensor coupled with the fluidic channel showed the enhancement of the electric signal responses for detection of E. coli K12, compared to the stationary sensor. A linear regression was observed for both the E. coli and S. aureus functionalized array sensors in the detection range of 10(2) to 10(5) CFU/mL. Multiplexed detection of bacteria at the sensing levels as low as 10(2) CFU/mL for E. coli K12 and S. aureus was achieved within 2 min. Therefore, the continuous flow multijunction biosensor shows potential for rapid and continuous multiplexed detection of foodborne pathogens.

Measurements of proportional scintillation and electron multiplication in liquid xenon using thin wires

Proportional scintillation in liquid xenon has a promising application in the field of direct dark matter detection, potentially allowing for simpler, more sensitive detectors.However, knowledge of the basic properties of the phenomenon as well as guidelines for its practical use are currently limited.We report here on measurements of proportional scintillation light emitted in liquid xenon around thin wires.The maximum proportional scintillation gain of 287−75+97 photons per drift electron was obtained using 10 μm diameter gold plated tungsten wire.The thresholds for electron multiplication and proportional scintillation are measured as 725−139+48 and 412−133+10 kV/cm, respectively.The threshold for proportional scintillation is in good agreement with a previously published result, while the electron multiplication threshold represents a novel measurement.A complete set of parameters for the practical use of the electron multiplication and proportional scintillation processes in liquid xenon was also obtained for the first time.

Investigation of the aging of gas-discharge detectors of particles with the use of nuclear reaction analysis

This paper reports on the results of an investigation into the aging of drift tubes with anodes fabricated from gold-plated tungsten wires under continuous irradiation with a 90Sr beta source. The accumulated charge is as high as 9 C cm−1. The process of aging is studied in a gaseous mixture containing Ar, CO2, and CF4. It is revealed that the aging brings about a severe damage of the gold coating on a tungsten wire and an increase in the diameter of the wire in the irradiated zone from 35 to 42 μm. The observed swelling of the anode wire under forces applied from the inside is apparently a new mechanism of aging of anode wires. The swelling effect is assumed to be caused by the oxidation of the tungsten wire. It is demonstrated using the nuclear reaction analysis that the deposits containing tungsten, oxygen, carbon, and fluorine are distributed along the anode wire in the direction of the gas flow. The oxygen and fluorine distributions over the depth and along the length of the anode wire are determined.

A radioactive point-source lattice for calibrating and monitoring the liquid xenon calorimeter of the MEG experiment

Liquid scintillator calorimeters and in particular liquid cryogenic noble gas detectors can be calibrated and monitored by the use of multiple α -sources distributed in the detector sensitive volume. For the MEG experiment we developed a method based on the use of Po 210 and Am 241 point sources deposited on thin ( 100 μ m diameter) gold-plated tungsten wires permanently suspended in the volume and fixed at the surfaces of the large vessel containing the LXe. The method is valuable in measuring the relative QEs of all PMTs surrounding the sensitive LXe volume, in determining the LXe optical properties for the UV scintillation light and in checking the stability of the calorimeter properties during the experiment.

Fabrication and characterization of innovative gas flow sensor

A hot-wire type flow sensor, as one arm of Wheatstone's bridge, is proposed using gold plated tungsten wire with innovative base material (soft ferrite) and geometry to enhance the mechanical stability and lifetime. The bridge excitation current is varied from 100 to 210 mA and the performance is tested using air as a flow gas. The flow sensor is calibrated for hydrogen (H 2) and carbon dioxide (CO 2). King's formula, which is comprehensively used in hot-wire anemometry, is verified for both the gases. The gas having higher thermal conductivity and lower molecular weight gives better response. This sensor can be used as flow gas analyzer. Response time of the sensor for this base material is few seconds. The repeatability and accuracy of the sensor is within ±1 and ±2% of full range (1–14 lpm), respectively.

Swelling phenomena in anode wires aging under a high accumulated dose

We present results from an aging investigation of straw drift-tubes placed under sustained irradiation from a 2 Ci 90Sr β-source. The aging phenomenon of gold-plated tungsten wires with diameters 25, 30 and 35 μm with accumulated charges up to 9 C/cm was studied thoroughly. Aging tests were carried out with different gas mixtures: 70% Xe+10% CO 2+20% CF 4, 60% Ar+30% CO 2+10% CF 4, 40% Ar+40% CO 2+20% C 2H 2F 4, and 60% Ar+30% CO 2+10% C 2H 2F 4. As a result of the aging process, the gold coating on the wires was damaged, and the wire diameter increased. For the first two gas mixtures, the wire swelling effect was concentrated only in the center of the irradiated zone. In comparison, the performance deterioration in the mixtures containing C 2H 2F 4 proved to be quite different. The gold coating on the wires was damaged, but outside the irradiating area. Large deposits were found on the wire surface, both in the vicinity of the irradiated zone and downstream of the gas flow. All deposits contained tungsten and oxygen, resulting in the local increase of the wire diameter by 36% (from 30 to 41 μm). Our data show that both aforementioned aging effects have a similar reason: the swelling of the wire material that creates forces within the anode wire and cracks the gold coating.

Anode wire swelling—a possible phenomenon in anode wire aging under high-accumulated dose

We present results from an aging investigation of straw drift tubes placed under sustained irradiation from an 90Sr (2 Ci) β-source. A thorough study of the aging phenomenon of the gold-plated tungsten wires with an accumulated charge of 9 C/cm was performed. Aging tests were performed with a gas mixture containing Xe, CO 2 and CF 4. As a result of the aging process, the gold coating on the wires was damaged, and the wire diameter increased from 35 to 42 μm. This phenomenon of anode wire swelling by forces applied from within the anode wire is a possible new aging mechanism. We show that this anode swelling effect can be explained by production of tungsten oxidation in the wire. Using Nuclear Reaction Analysis (NRA), in combination with an SEM/XEM analysis, it is determined that deposits containing tungsten and oxygen are distributed along the wire corresponding to the gas flow direction. The concentration of oxygen as a function of depth within the wire has also been investigated using NRA, and it is shown that oxygen transportation into the depth of the wire occurs.

Application and methodological improvements to the floating-wire technique to characterize the magnetic properties of a spectrometer dipole

The floating wire technique was applied to characterize the focusing properties of the D2 spectrometer magnet to be used in the ANKE installation of the COSY Jülich accelerator facility. Trajectories corresponding to 140–600 MeV/c ejectiles emerging from a target in front of the rectangular-type D2 magnet were measured in order to determine the location of foci where detectors for the physics experiments were to be placed. The focus for trajectories of the same momentum was localized by varying the trajectory start angle at the target. To overcome the problem of instability, which arises when the pulley has to be located behind the focus, an unbalanced pulley was used. Other improvements include methodological features such as the particular design of our air-bearing pulley enabling a “freezing-in” of the wire movement and therefore yielding a very high accuracy of the wire position measurement, the use of a 40 μm gold-plated tungsten wire best fulfilling the mechanical and electrical requirements, a fast-regulating power supply in combination with an absolutely calibrated current meter, and the excellent accuracy of modern surveying instrumentation. An overall momentum accuracy of Δp/p⩽10−3 and a position accuracy of the trajectories of ±1 mm in the vicinity of the foci have been demonstrated. The precision and accuracy of the floating-wire measurements are discussed and compared with ray-tracing calculations based on measured and calculated field maps.

A large area two-dimensional position sensitive multiwire proportional detector

Abstract Large area two-dimensional position sensitive multiwire proportional detectors were developed to be used in the study of light heavy-ion nuclear reactions at the University of Sao Paulo Pelletron Laboratory. Each detector has a 20×20 cm2 active area and consists of three grids (X-position, anode and Y-position) made of 25 μm diameter gold plated tungsten wires. The position is determined through resistive divider chains. Results for position resolution, linearity and efficiency as a function of energy and position for different elements are reported.

A novel nonmetallized tip for electrospray mass spectrometry at nanoliter flow rate

We report the fabrication of a durable nonmetallized nanospray tip. This nanospray tip does not require complex preparation procedures such as chemical treatment, deposition of gold or SiOx vapor. It was fabricated by pulling a heated glass capillary of 1.1 mm internal diameter to produce a fine tip with an orifice of 10–15 μm in diameter. A 10 μm gold-plated tungsten wire was inserted through the capillary tip. This tungsten wire played a central role in the operation of this durable nanospray tip by providing electrical contact. This type of nanospray tip could withstand electrical discharges and sustained spraying of solution at nanoliter flow rate for more than 3 h. Using insulin (35 μM) and myoglobin (1 μM) solutions, useful mass spectrum could be acquired with low fmol sensitivity.

Test of new light-and-strong material for anode wires of wire chambers

We have tested a new type of steel wires for anode wires of wire chambers. The measured yield strength of 50 μm diameter wires of this material is 500–650 g, as compared to 430 g for tungsten wires. As used for the anode wires of proportional tubes, no significant difference of signals was observed between the wires of this material and the gold-plated tungsten wires. Wire sags, δ, in units of μm, are expressed as δ = 3.2 L 2, for 50 μm diameter wires of this material when 600 g tension is applied, where L is the length of the wire in m.

The brain slicer: Anatomical precision for organotypic expiant culture

A brain slicing apparatus originally developed for electrophysiological studies of cat visual cortex slices has been used to prepare expiants from anatomically identifiable regions of the developing CNS for long-term organotypic culture in Maximow double coverslip assemblies. This instrument permits the very rapid, reproducible and atraumatic preparation of viable explants from specific brain regions with an optimal thickness range of 350–400 μm. The stainless steel cutting grid with its gold-plated tungsten wires and the Agarose cutting base are nontoxic and easy to sterilize. The degree of atlas-quality, anatomic precision achieved makes the brain slicer also uniquely suited for the preparation of anatomically defined brain regions for use as transplants.

Cosmic ray tests of 7.6 m drift-tube counters and the readout electronics system of the VENUS muon detector

Eight-cell drift-tube modules of 7.6 m in length and the readout electronics system of the VENUS muon detector at KEK have been tested by using cosmic rays in order to evaluate the performance of the system. The cross section of each cell is 5 × 7 cm 2. The anode wire is a gold-plated tungsten wire with a diameter of 70 μm. P10 gas ( Ar/CH 4 = 90 10 ) was used at 1 atm. Typical singles rates in the high voltage plateau region were about 220 Hz per wire which is slightly higher than the estimated cosmic ray rate of 150 Hz. The average dark current was about 6 nA per wire at an operating high voltage of 2.7 kV. The spatial resolution for a single tube has two distinct components. The main component contains about 96% of the total incident events and has an rms spatial resolution of about 1.3 mm. The second component has a much broader distribution with an rms value of about 12 mm. It is evident that these events are caused by delta-rays generated in the tube wall. The detection efficiency is essentially 100% if the two components are included.

Wire Aging of Hydrocarbon Gases with TMAE Additions

We report on experimental results describing wire aging properties of the CRID/RICH detectors in the TMAE gas environment. This test used 7, μm and 33 μm diameter carbon fibers, and 20 μm diameter gold-plated tungsten wires as sense wires, and operated in gas mixtures of either CH4 or C2H6 at 1 atm, together wth 0.6 Torr of the photoionizing vapor TMAE (tetrakis dimethylamino ethylene), which serves as a photocathode in the CRID detectors. The wires were damaged by the Fe55 X-rays. This paper is based on irradiation of 20 wires, each being a separate test. The gas purity was consistent with requirements of CRID detectors (< 1 ppm of oxygen, < 1 ppm of water). The test explored the aging as a function of wire diameter, wire material, gas flow, gas temperature, rate of radiation and gas type. Several chemical analyses of the deposit samples were performed (FTIR, ESCA and GC-MS techniques).

Multielement Proportional Chamber for 136Xe ββ decay

A Multielement Proportional Chamber designed to investigate ββ decay of 136Xe is described. The detector consists of 61 cells. arranged in a honeycomb structure. Each cell is 80 cm long and has a hexagonal cross section of 2.5 cm side. The anodes are 20 μm diameter gold plated tungsten wires. Each cathode consists of 24 copper-beryllium wires of 100 μm diameter. This structure is mounted in a titanium vessel of 40 cm diameter and 110 cm length. In order to obtain a very low background all the materials used were selected for their low intrinsic activities. The detector is operated with Xe at 10 bar; a purification system keeps the oxygen like impurities below 0.2 ppm. The electronics consists of 61 hybrid charge sensitive preamplifiers followed by 7 bit CAMAC flash-ADCs to digitize and store the pulses. An auxiliary output of the preamplifier is used to drive a trigger module that can be preset to any configuration of total energy and/or anode pattern. The chamber, presently under test, will soon be installed in the Gran Sasso underground Laboratory for data taking. Measurements on energy resolution over several cells and on charge transport are described.

A Drift Multiwire Proportional Counter for Cosmic Soft X-Ray Imaging

Multiwire proportional counters with 1 ?m polypropylene windows, of dimensions 75 mm × 75 mm and 100 mm × 100 mm, have been built to map soft cosmic X-rays. The counters are constructed with a large drift region which allows us to use the center-of-gravity technique to improve the counter's efficiency and position resolution. Using 330 Torr of propane as the gas fill and an anode plane composed of 20 ?m diameter, gold-plated tungsten wire spaced 1 mm apart, we have achieved a position resolution of better than 280 ?m (FWHM) in two orthogonal directions at an X-ray energy of 0.94 keV.