Cathode readout of limited streamer tubes with conductive plastic walls

The performance of cathode readout on the limited streamer drift tubes with conductive plastic wall was studied. Cathode strips were placed on the outside of tubes in parallel and perpendicular to the anode wires. It was found that conductive plastic walls broadened the induced charge distribution on the cathode strips perpendicular to the anode wire. Position resolution of 420–450 μm was obtained along the anode wire, and parallel strips were found to be useful to solve left-right ambiguities in the drift chamber readout.     

First results from a silicon-strip detector with VLSI readout

A 256-strip silicon detector with 25 μm strip pitch, connected to two 128-channel NMOS VLSI chips (Microplex), has been tested using straight-through tracks from a ruthenium beta source. The readout channels have a pitch of 47.5 μm. A single multiplexed output provides voltages proportional to the integrated charge from each strip. The most probable signal height from the beta traversals is approximately 14 times the rms noise in any single channel.     

The ALEPH minivertex detector

Vertex detectors allow high precision reconstruction of particle tracks and therefore make possible the investigation of the decay topology of short-lived particles in collider experiments.In the ALEPH experiment at LEP a minivertex detector will be installed. It consists of silicon microstrip detectors arranged on two concentric “cylindrical” surfaces around the interaction point. With this geometry it will be possible to measure the r − ϕ − z coordinates of particles traversing the detector. The expected position resolution is 10 μm in r − ϕ and 20 μm in r − z.For optimum signal processing monolithic CMOS readout electronics are under development. Each chip consists of 60 charge sensitive preamplifiers, multiplexed into one output channel. Fast power switching will reduce heat dissipation.Details about construction and expected device performance will be described.     

Electrical Readout of Protein Microarrays on Regular Glass Slides

A new approach for the electrical readout of microarrays prepared on regular glass slides, using an array of impedimetric transducers (interdigitated electrodes, IDEs) is presented in this work. Impedance detection relies on the use of a urease-labeled immunoassay scheme. Urease is able to produce an increase in conductivity by hydrolysis of the urea substrate, which is measured with the IDEs and directly related to the amount of target analyte. Unlike previous electrical microarrays, the assay does not take place on top of the transducers but on a regular glass slide, which may enable the development of compact multiplexed analytical systems with lower cost per assay. A droplet of solution with the enzymatic substrate is deposited on each transducer of the array, and the microarray is positioned at a short distance (300 μm) so that each droplet wets one transducer and one spot of the microarray. This procedure allows reusing the transducer array for readout of a virtually unlimited number of microarrays. A microarray based on an immunoassay for the detection of a mouse generic protein in a concentration range from 0.03 to 30 μg mL(-1) was carried out to assess the performance of the electrical readout approach. A sigmoid response with a limit of detection of 0.1 μg mL(-1) and a dynamic range of 1 order of magnitude was obtained. A comparative study was also carried out with two well established analytical procedures. First, the urease-based immunoassay was tested in a 96 well microtiter plate using phenol red pH indicator and absorbance detection. Second, the microarray was carried out using the same target protein concentration range but applying a Cy3 label and fluorescence detection. Both assays allowed for the validation of the performance of the presented electrical readout system.     

Organic Mott insulator-based nanowire formed by using the Nanoscale-electrocrystallization

We obtained organic Mott insulator nanowire by using the Nanoscale-electrocrystallization. The ac electrocrystallization provided nanowires only in the gap between two electrodes though dc yielded them over the anode surface. These nanowires ranged in width from 50 nm to several hundred nm and were several μm in length. We also measured their i-V characteristics.     

The X-HPD—conceptual study of a large spherical hybrid photodetector

We present the results of a conceptual study demonstrating the feasibility of a large spherical hybrid photodetector with central anode. A prototype tube with 208 mm diameter and an anode in form of a metallic cube has been fabricated. In the final version of the so-called X-HPD concept the anode will be a scintillator cube with plated faces and a small photodetector to readout the bottom. The bialkali photocathode covers three quarters of the sphere surface. Combined use of this cathode in transmissive and reflective mode leads to effective quantum efficiency values exceeding those obtained in conventional hemispherical PMT designs. Further features of the concept are a photoelectron collection efficiency approaching 100% and a photon amplification in the scintillator crystal leading to a distinct single photoelectron signal.

Using a custom built electron accelerator based on a CsI transmissive photocathode, LSO and YAP block crystals in geometries adapted to the anode of an X-HPD have been tested with single photoelectrons in the 10–30 keV energy range. The scintillation light was readout with a conventional PMT or a Si-PM. More than 30 photoelectrons per incident electron could be detected with the PMT.     

An improved quadrant anode image sensor with microchannel plates

We describe a position-sensitive event-counting microchannel plate detector with a quadrant anode readout system that combines the advantages of several centroid-finding readout techniques. The relative amount of charge collected by each quadrant of the anode mounted behind the output side of the microchannel plate is used to localize each event. The position-sensitive area is about 80% of the active microchannel plate surface. By changing a single voltage a remote-controlled image magnification can be achieved. Due to a correction function that minimizes image distortions the imaging characteristics of this low-cost readout system are similar to those of expensive resistive anodes.     

A Superconducting Resonator with a Hafnium Microbridge at Temperatures of 50–350 mK

A high-quality superconducting resonator with a microbridge of hafnium film for use in a circuit for readout a terahertz-band imaging array with frequency division multiplexing is demonstrated experimentally. The variability of the impedance of the bridge at a frequency of 1.5 GHz, which is a key factor in the control of the quality of the resonator, is studied. The bridge, having a thickness of about 50 nm, a critical temperature T_C ≈ 380 mK, and a plan size of 2.5 × 2.5 μm, was connected as a load of a resonator made of niobium film with a thickness of about 100 nm (T_C ~ 9 K). It is shown that the bridge smoothly changes its impedance proportionally to the bias power in the entire temperature range. The effective thermal insulation of the bridge was measured in a dilution cryostat at temperatures of 50–300 mK. Thermal conductivity G of the bridge was calculated and found to be ~4 × 10^–13 W/K, which gives an estimate of the sensitivity of the structure in the bolometric mode NEP ≈ 8 × 10^–19 W/Hz^1/2 at a temperature of 150 mK.     

Heat transfer enhancement and critical heat fluxes in boiling of microfinned surfaces

A brief review is presented of experimental investigations of heat transfer enhancement during boiling on surfaces with nano- or microstructure. Distilled water boiling on microfinned surfaces made by deforming cutting was investigated. It was found that, for distilled water boiling on these surfaces with 3D microfinning (having an interfin gap of u = 120–180 μm, a microfin height of h = 340–570 μm, and a microfin pitch of w = 240–400 μm), heat transfer increased by a maximum factor of 4 to 5 as compared with that on smooth surfaces. Critical heat fluxes increase by a factor of up to 6 as compared with boiling on smooth surfaces.     

High resolution digital autoradiography of short and long range β− emitters using a single step parallel plate chamber

The use of single step parallel plate counter for the two-dimensional imaging of β⁻ emitters is discussed. The parallel plate chamber has a resistive germanium anode and a cathode made up of a nickel mesh having 600 line pairs/in. A ≈500 μm (fhwm) resolution for ³H and a ≈1 mm (fwhm) resolution for ¹⁴C have been measured.     

A position sensitive microchannelplate detector using a delay line readout anode

A new method for a two-dimensional position encoding system with microchannelplates (MCPs) involving a delay line readout anode is described. The resolution of the time measurement is 500 ps corresponding to a position resolution of 0.25 mm.     

High resolution silicon detectors for colliding beam physics

Resolution and linearity of the position measurement of Pisa multi-electrode silicon detectors are presented. The detectors are operated in slightly underdepleted mode and take advantage of their intrinsic resistivity for resistive charge partition between adjacent strips. 22 μm resolution is achieved with readout lines spaced 300 μm. Possible applications in colliding beam experiments for the detection of secondary vertices are discussed.     

Latest results from silicon microstrip detectors with VLSI readout for the delphi microvertex detector

A silicon microstrip counter with 25 μm strip pitch and two 128-channel low noise VLSI readout chips (“MICROPLEX”) has been tested in a 3.5 GeV negative pion beam at CERN. Results are given on the signal-to-noise ratio and on the cluster size spreading due to capacitive crosstalk.     

High pT trigger electronics for a large orthogonal readout electromagnetic calorimeter

A trigger system has been designed and built to select events containing high p_T electromagnetic showers detected in a large calorimeter with orthogonal readout. The electronics include analog adders with up to 123 inputs, pulse shapers with 20 ns integration time, 100 MHz flash ADCs and ECL loop-up tables. The total number of input channels is 3072 and the trigger decision is made in about 120 ns.     

Narrow track readout with magnetic garnet film

A novel magneto-optic readout head, which utilizes the modulation of width of straight domains in a garnet film in response to the fringing field from the recording medium, was evaluated from the viewpoint of narrow track readout. In a static transfer experiment with a garnet film having a domain width of 2.25 μm, a definite transfer to the garnet film with track widths of 3 μm or less was confirmed. An expression for the modulation degree of the domain width was derived, and its predictions agreed well with the experimental results. In the dynamic readout experiment, a carrier-to-noise ratio of 50 dB was obtained for a trackwidth of 4 μm and a wavelength of 10 μm. The cross-talk was -30 dB when the track-to-track spacing and track width were 10 μm and 5 μm, respectively. From these results the feasibility of narrow track readout based on this head was demonstrated. The readout performance, including the decrease of readable track width, the wavelength and crosstalk, can be greatly improved if a garnet film, having a domain width narrower than that used in this experiment is used together with a high-density recording medium.     

Drift chamber readout with flash ADCs: I. Time and spatial resolution

A systematic study of the time, space, and double track resolution for drift chambers with a 100 MHz flash ADC readout is reported. The dependence of the spatial resolution on gas pressure, electric field, drift distance, and the algorithms used for pulse shape analysis has been investigated. At 4 bar gas pressure a spatial resolution of better than 125 μm was obtained for drift distances up to 20 cm. The double track resolution is ≲ 3 mm.     

Ion-implanted capacitively coupled silicon strip detectors with integrated polysilicon bias resistors processed on a 100 mm wafer

Double-sided silicon strip detectors with integrated coupling capacitors and polysilicon resistors have been processed on a 100 mm wafer. A detector with an active area of 19 × 19 mm² was connected to LSI readout electronics and tested. The strip pitch of the detector is 25 μm on the p-side and 50 μm on the n-side. The readout pitch is 50 μm on both sides. The number of readout strips is 774 and the total number of strips is 1161. On the p-side a signal-to-noise of 35 has been measured using a ⁹⁰Sr β-source. The n-side has been studied using a laser.     

The readout method for wire chambers

The method for readout of information from a wire chamber through a conventional conductive wire cathode is tested to study the possibility of its practical usage. It is observed that the value of the signal induced on an external readout electrode depends on the detector geometry and makes up approximately 5–10% of the anode signal value. The application of this method should permit one to separate a detector into an active device and an independent readout system as well as to make the readout system more flexible and to improve detector coordinate properties.     

Improvement of the anode performance of graphite particles through surface modification in RF thermal plasma

Mesocarbon microbeads (MCMB) powders, which are known to be highly crystallized carbon materials and have a mean particle size of 11 μm, were treated in RF thermal plasma. Through the plasma treatment, the surface morphology, structure, and chemical composition of the powder were modified. The plasma-induced modification made the surface of MCMB particles disordered, and gave rise to an improvement in the thermal stability and electrochemical properties of the powders, such as the discharge capacity and first charge/discharge efficiency. It also made the powders suitable for further use as an anode in lithium-ion rechargeable batteries. Powders obtained without air exposure showed further improvement in anode performance.     

Comparison of readout characteristics between magnetooptic transferheads and magnetic heads

The readout characteristics of a magnetooptic transfer (MOT) head were compared with those of a magnetic head. Magnetic recording/readout was done on a CrO₂ flexible disk by using a head with a track width of 5 μm. A Bi-substituted garnet film with a domain width of 1.2 μm and an He-Ne laser spot focused down to 3 μm were used as the MOT head. Readout waveforms from both heads were surprisingly similar. The maximum carrier-to-noise ratio obtained was 50 dB (bandwidth: 30 kHz) for both heads. Experimental data for off-track and crosstalk characteristics demonstrated that the MOT head was suitable for use as a high-track-density readout head. The potential advantages of multitrack readout using MOT heads are described