Resistive Anode Research Articles

Characterization and Calibration of Large Area Resistive Strip Micromegas Detectors

Resistive strip Micromegas detectors have been tested extensively as small detectors of about 10×10cm2 in size and they work reliably at high rates of 100kHz/cm2 and above. Tracking resolution well below 100μm has been observed for 100GeV muons and pions. Micromegas detectors are meanwhile proposed as large area muon precision trackers of 2–3m2 in size. To investigate possible differences between small and large detectors, a 1m2 detector with 2048 resistive strips at a pitch of 450μm was studied in the LMU Cosmic Ray Measurement Facility (CRMF) using two 4×2.2m2 large Monitored Drift Tube (MDT) chambers for cosmic muon reference tracking. A segmentation of the resistive strip anode plane in 57.6mm×93mm large areas has been realized by the readout of 128 strips with one APV25 chip each and by eleven 93mm broad trigger scintillators placed along the readout strips. This allows for mapping of homogeneity in pulse height and efficiency, determination of signal propagation along the 1m long anode strips and calibration of the position of the anode strips.

A position-sensitive micro-channel plate detector with a parallel-strip resistive anode and integrated charge-sensitive amplifiers

A one-dimensional position-sensitive micro-channel plate detector with parallel-strip resistive anode and dedicated amplifiers has been constructed. The detector is tested by a 241Am α -source and the spatial resolution of 0.2 mm is achieved.

Using pulse shape analysis to improve the position resolution of a resistive anode microchannel plate detector

Digital signal processing techniques were employed to investigate the joint use of charge division and risetime analyses for the resistive anode (RA) coupled to a microchannel plate detector (MCP). In contrast to the typical approach of using the relative charge at each corner of the RA, this joint approach results in a significantly improved position resolution. A conventional charge division analysis utilizing analog signal processing provides a measured position resolution of 170μm (FWHM). By using the correlation between risetime and position we were able to obtain a measured resolution of 92μm (FWHM), corresponding to an intrinsic resolution of 64μm (FWHM) for a single Z-stack MCP detector.

Optimizing the position resolution of a Z-stack microchannel plate resistive anode detector for low intensity signals.

A method for achieving good position resolution of low-intensity electron signals using a microchannel plate resistive anode detector is demonstrated. Electron events at a rate of 7 counts s(-1) are detected using a Z-stack microchannel plate. The dependence of position resolution on both the distance and the potential difference between the microchannel plate and resistive anode is investigated. Using standard commercial electronics, a measured position resolution of 170 μm (FWHM) is obtained, which corresponds to an intrinsic resolution of 157 μm (FWHM).

Effect of Bismuth Oxide as Sintering Aid for Gadolinia-doped Ceria at 1050°C

Dense GDC electrolytes can work as high ion-conducting material for innovative IT-SOFCs. These electrolytes will be used as a base to develop sulfur resistant anodes using copper oxide and GDC, in order to avoid the use of nickel oxide. An aqueous tape casting process to produce dense gadolinia-doped ceria (GDC) electrolyte was developed. The study developed in three main steps. First, the dispersant concentration was idealized for slurries consisting of only distilled water, an ammonium polyacrylate (PAA) dispersant and ceramic powder (commercial Ce0.9Gd0.1O1.95). By examining the rheological behavior of the slurry, the ideal ratio between the active part of dispersant and powder surface was found to be between 0.15 and 0.30 mg/m2 . Second, starting with the dispersed slurry, fixed amounts of acrylic binder and plasticizer were added and the pH was varied in order to identify the optimum pH interval in which the suspension is stable and no agglomerates form. The ideal pH was found to be between 8 and 9. Finally, the amounts of binder and plasticizer were varied and the suspensions were tape casted (thickness 200 µm) to produce a defect free, smooth and high relative green density (about 50%) tape. SEM observations of samples sintered at 1500 °C showed satisfactory dense section profile (about 95%). Figure 1

High rate and durable, binder free anode based on silicon loaded MoO3 nanoplatelets.

In order to make fast-charging batteries a reality for electric vehicles, durable, more energy dense and high-current density resistant anodes need to be developed. With such purpose, a low lithiation potential of 0.2 V vs. Li/Li+ for MoO3 nanoplatelet arrays is reported here for anodes in a lithium ion battery. The composite material here presented affords elevated charge capacity while at the same time withstands rapid cycling for longer periods of time. Li2MoO4 and Li1.333Mo0.666O2 were identified as the products of lithiation of pristine MoO3 nanoplatelets and silicon-decorated MoO3, respectively, accounting for lower than previously reported lithiation potentials. MoO3 nanoplatelet arrays were deposited using hot-wire chemical vapor deposition. Due to excellent voltage compatibility, composite lithium ion battery anodes comprising molybdenum oxide nanoplatelets decorated with silicon nanoparticles (0.3% by wt.) were prepared using an ultrasonic spray. Silicon decorated MoO3 nanoplatelets exhibited enhanced capacity of 1037 mAh g−1 with exceptional cyclablity when charged/discharged at high current densities of 10 A g−1.

SIMS evaluation of poly crystal boron nitride tool effect in thermo-mechanically affected zone of friction stir weld steels

The effect of the poly crystal boron nitride (PCBN) tool in friction stir weld (FSW) steels was evaluated using the secondary ion mass spectroscopy (SIMS) technique. This study focused on the quantitative SIMS analysis of impurity boron through a resistive anode encoder (RAE) image. The RAE images were transformed retrospective depth profile by profiler. The relative sensitivity factors (RSFs) for boron varied heavily according to by the polarity of secondary voltage and matrix materials. The RAE images of cluster-polyatomic secondary ion species, 11B16O2, properly map the distribution of impurity boron in the thermo-mechanically affected zone (TMAZ) of FSW steels using negative secondary polarity 4.5 kV. A combination of cluster-polyatomic ion, 11B16O2 and 56Fe16O provided a good calibration curve by 3 SRMs with the least matrix effect. The boron concentrations of TMAZ in FSW steels were determined through the calibration curve by taking the corresponding boron concentration value (CB) of the intensity ratio (Ii/Im) from unknown samples. The new SIMS quantification technique of impurity boron from RAE images is found to be effective for a more quantitative understanding of the wear mechanism of the PCBN tool in TMAZ of FSW steels.

Laboratory studies of THGEM-based WELL structures with resistive anode

In this work we investigate three variants of single amplification-stage detector elements; they comprise THGEM electrodes closed at their bottom with metallic or resistive anodes to form WELL-type configurations. We present the results of a comparative study of the Thick-WELL (THWELL), Resistive-WELL (RWELL) and Segmented Resistive WELL (SRWELL) focusing on their performance in terms of spark-quenching capability, gain variation with position and counting rate, pulse shapes and signal propagation to neighboring readout pads; the study included both 30 × 30 and 100 × 100 mm2 detectors. It was shown that the WELL structures with resistive anodes offer stable operation even in a highly ionizing environment with effective spark quenching, as well as higher gain than the standard THGEM/inductiongap configuration. Cross talk between neighboring readout pads (here 10 × 10 mm2 in size) was shown to be effectively eliminated in the segmented detector with a conductive grid underneath the resistive layer. The latter multiplier should allow for the design of very thin detectors, e.g. sampling elements in digital hadronic calorimeters planned for experiments in future linear colliders.

Doped Samarium Ferrite Perovskites as Carbon and Sulfur Resistant Anodes for Low Temperature Solid Oxide Fuel Cells

Perovskite type oxides (ABO3) have opened a new door to solve operational issues of SOFC anodes. One of the great advantages of these materials is that their properties can be easily tailored according to the desired applications, by introducing substitutions at A and B- sites. Doping Ce, Co and Ni in SmFeO3 solves not only the reduction instability issue of these perovskites, but also makes these materials suitable as anodes. The resistance to coke formation is shown for three prime candidates of this perovskite family (Sm0.95Ce0.05FeO3-δ, Sm0.95Ce0.05Fe0.97Co0.03O3-δ, and Sm0.95Ce0.05Fe0.97Ni0.03O3-δ). These anodes show stable performance in pure methane fuel in the temperature range of 450 to 650°C. In addition, performance of these anodes in the presence of 5% H2S is higher than for pure H2.

The Readout Electronics of the Micromegas-Based Large Time Projection Chamber Prototype for the International Linear Collider

This work presents the design, implementation and test of prototype modules of a Time Projection Chamber based on Micromegas amplification technology which was built in view of the future International Linear Collider. The main goals of this development are to investigate the performance of the detector and to demonstrate the feasibility of extremely compact and low power readout electronics. We based the front-end electronics on the AFTER chip, a 72-channel ASIC originally built for the T2K experiment, and integrated it with new hardware, mechanics and cooling to read out the 1728 channels of a detector module while staying confined in the available area of ~ 220 cm2. The digital part of a module is based on a Xilinx Virtex-5 FPGA which interfaces to the 24 AFTER chips used for the readout. We present the operation of a vertical slice of the complete detector and readout system. In particular, our tests show that the resistive anode of the Micromegas detector, which is primarily designed to improve tracking resolution, allows operation without the spark protection circuit normally required on each readout channel.

External quantum efficiency enhancement in organic photovoltaic devices employing dual organic anode interfacial layers

We demonstrate the use of a dual anode interfacial layer of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) and tetracene for efficient small molecule organic solar cells. These layers provided a multifaceted improvement on device performance by enhancing absorption in the donor layer, serving as an exciton blocking layer at the anode interface, providing a low resistance anode contact, and serving as a templating layer for increased crystallinity in the donor layer. Palladium phthalocyanine/C60 planar heterojunction devices fabricated on top of the dual layers of PEDOT:PSS and tetracene demonstrates 85% enhancement in the donor contribution to external quantum efficiency and yielded a maximum power conversion efficiency of 3.66%.

Recent progress on solid oxide fuel cell: Lowering temperature and utilizing non-hydrogen fuels

A solid oxide fuel cell (SOFC) is a promising energy conversion device with high efficiency and low pollutant emission. The practical application of the conventional SOFCs is limited mainly because of their high operating temperature and the inconvenience brought by the H2 fuel utilization. This work reviews the recent progress on intermediate temperature SOFCs especially with non-hydrogen fuels. Composite electrolyte consisting of a solid oxide ionic conducting phase and a molten carbonate phase exhibits sufficient ionic conductivity in the intermediate temperature range, i.e. 500–800 °C, and facilitates the simultaneous conduction of H+, O2− and CO32− ions. A single cell with the composite electrolyte shows a promising power density, 1700 mW cm−2 at 650 °C with hydrogen as the fuel. The composite electrolyte has been also employed in a direct carbon fuel cell (DCFC), and the simultaneous conduction of O2− and CO32− in the electrolyte has been proposed. Recently, perovskite structured materials are found to have good resistance to coke formation as the anode of the direct hydrocarbon solid oxide fuel cell, and several carbon resistant perovskite anodes are employed in all-perovskite structured SOFCs, which exhibit excellent performance with CH4 and methanol as the fuel.

Beam studies of the segmented resistive WELL: A potential thin sampling element for digital hadron calorimetry

Thick Gas Electron Multipliers (THGEMs) have the potential of constituting thin, robust sampling elements in Digital Hadron Calorimetry (DHCAL) at future colliders. We report on recent beam studies of new single- and double-THGEM-like structures: the multiplier is a Segmented Resistive WELL (SRWELL) – a single-faced THGEM in contact with a segmented resistive layer inductively coupled to readout pads. Several 10×10cm2 configurations with a total thickness of 5–6mm (excluding electronics) with 1cm2 pads were investigated with muons and pions. The pads were coupled to a scalable readout system APV chip, APV-SRS (Raymond et al. [22]). Detection efficiencies in the 98% range were recorded with an average pad-multiplicity of ~1.1. The resistive anode resulted in efficient discharge damping, with potential drops of a few volts; the discharge probabilities were ~10−7 for muons and ~10−6 for pions, at rates of a few kHz/cm2 and for detectors in the double-stage configuration. Further optimization work and research on larger detectors are underway.

Beam studies of novel THGEM-based potential sampling elements for Digital Hadron Calorimetry

Beam studies of thin single- and double-stage THGEM-based detectors are presented. Several 10 × 10 cm2 configurations with a total thickness of 5–6 mm (excluding readout electronics), with 1 × 1 cm2 pads inductively coupled through a resistive layer to APV-SRS readout electronics, were investigated with muons and pions. Detection efficiencies in the 98% range were recorded with an average pad-multiplicity of ∼ 1.1. The resistive anode resulted in efficient discharge damping, with few-volt potential drops; discharge probabilities were ∼ 10−7 for muons and 10−6 for pions in the double-stage configuration, at rates of a few kHz/cm2. These results, together with the robustness of THGEM electrodes against spark damage and their suitability for economic production over large areas, make THGEM-based detectors highly competitive compared to the other technologies considered for the SiD-DHCAL.

Vapor-deposited hydrogenated and oxygen-deficient molybdenum oxide thin films for application in organic optoelectronics

Vapor-deposited molybdenum oxide films are used as low resistance anode interfacial layers in applications such as organic light emitting diodes (OLEDs) and organic photovoltaics (OPVs). A versatile method for the vapor deposition of molybdenum oxide layers is presented, which offers the control of the oxygen stoichiometry of the deposited films and their doping with hydrogen. The possibility of tuning the electronic structure of the deposited molybdenum oxides is also investigated by controlling oxygen deficiency and hydrogenation (the incorporation of hydrogen within the molybdenum oxide's lattice). To take advantage of the altered electronic properties of the non-stoichiometric Mo oxides, we embedded them as anode interfacial layers in organic optoelectronic devices. Large improvement in the operational characteristics of both electroluminescent devices and bulk heterojunction solar cells was achieved and correlated with the oxygen deficiency and the hydrogen content of the Mo oxides.

Study of 2D interpolating readout for a micro-pattern gaseous detector

The two-dimensional interpolating readout, a new readout concept based on resistive anode structure, was studied for the micro-pattern gaseous detector. Within its high spatial resolution, the interpolating resistive readout structure leads to an enormous reduction of electronic channels compared with pure pixel devices, and also makes the detector more reliable and robust, which is attributed to its resistive anode relieving discharge. A GEM (gaseous electron multiplier) detector with 2D interpolating resistive readout structure was set up and the performance of the detector was studied with 55Fe 5.9 keV X-ray. The detector worked stably at the gain up to 3.5×104 without any discharge. An energy resolution of about 19%, and a spatial resolution of about 219 μm (FWHM) were reached, and good imaging performance was also obtained.

Solid Oxide Fuel Cells with Symmetrical Pt-YSZ Electrodes Prepared by YSZ Infiltration

Platinum electrodes for high temperature electrochemical devices (solid oxide fuel cells, solid oxide electrolyzer cells and sensors) generally show limited performances due to confinement of triple phase boundaries (TPBs) to the Platinum-electrolyte interface. Performance degradation as a result of TPB length loss due to the microstructural instability of the Platinum electrodes at operational temperatures is the other major problem. Infiltration of yttrium stabilized zirconia (YSZ) into porous Platinum electrodes using polymeric metal-oxide precursor was utilized as a prospective solution to these problems. It was shown that this process formed a YSZ coating on the Platinum particle surface which led to significantly increased effective contact area between Platinum electrodes and the electrolyte, and prevented the coarsening of Platinum. Symmetrical cells with YSZ infiltrated Platinum electrodes showed polarization resistance of 0.045 Ohm.cm2 per cathode at 800°C, in air. In fuel cell operation mode, the total electrode polarization resistance (anode + cathode) was 0.35 Ohm.cm2 at 800°C and 0.130 Ohm.cm2 at 900°C. Power densities of 0.45 Watt/cm2 and 0.9 Watt/cm2 at 800°C and 900°C were obtained respectively. No degradation of the cell was observed for the duration of measurement (248 hours).

A new position sensitive anode for plasmas diagnostic

The studies of plasmas generated by laser-matter interaction requires detectors that are able to perform the time resolved imaging of photons and charged particles. Such information are necessary in order to characterize the time evolution of fundamental parameters (as temperature, density, etc.) of plasma. One of the key elements of such diagnostics is the position sensitive anode. We are studying a new type of position-sensitive anode which will be realized by using silicon planar technology: a trapezes and stripes resistive anode (TSRA). The new TSRA is a two-dimensional system, which can be coupled with one of two-stage multichannel plates for the particles detection or for photons.

Study of a bulk-Micromegas with a resistive anode

The design and performance of a Micromegas with a resistive anode are presented in this paper. A thin resistive sheet with volume resistivity of 1012 Ω · cm is glued onto the readout electrode surface and its performance is investigated by using a 55Fe X-ray radioactive source in the operation gas of argon and isobutene mixtures (Ar/Iso=95/5). The gas gain at different mesh high voltage, counting rate and working time are given. Energy spectra at different working voltages are measured and the results are discussed. We have oberved that a Micromegas with a resistive anode can be operated at higer gain than a standard Micromegas without sparks.

Performances and Ageing Study of Resistive-Anodes Micromegas Detectors for HL-LHC Environment

With the tenfold luminosity increase envisaged at the HL-LHC, the background (photons, neutrons, ...) and the event pile-up probability are expected to increase in proportion in the different experiments, especially in the forward regions like, for instance, the muons chambers of the ATLAS detector. Detectors based on the Micromegas principle should be good alternatives for the detector upgrade in the HL-LHC framework because of a good spatial (<100 \mum) and time (few ns) resolutions, high-rate capability, radiation hardness, good robustness and the possibility to build large areas. The aim of this study is to demonstrate that it is possible to reduce the discharge probability and protect the electronics by using a resistive anode plane in a high flux hadrons environment. Several prototypes of 10x10 cm2, with different pitches (0.5 to 2 mm) and different resistive layers have been tested at CERN (pi+@SPS). Several tests have been performed with a telescope at different voltages to assess the performances of the detectors in terms of position resolution and efficiency. The spark behaviour in these conditions has also been evaluated. Resistive coating has been shown to be a successful method to reduce the effect of sparks on the efficiency of micromegas. A good spatial resolution (~80 \mum) can be reached with a resistive strip coating detector of 1mm pitch and a high efficiency (> 98%) can be achieved with resistive-anode micromegas detector. An X-rays irradiation has been also performed, showing no ageing effect after more than 21 days exposure and an integrated charge of almost 1C.