Design Of Counter Research Articles

Editorial - Design, Construction and Use of Tissue-Equivalent Proportional Counters

Editorial - Design, Construction and Use of Tissue-Equivalent Proportional Counters

Practical Considerations in the Design and Construction of Tissue-Equivalent Proportional Counters

The design and construction techniques required to produce high quality tissue-equivalent proportional counters are not difficult, but there are a few special considerations. Since there are many options at each stage of the design and construction, and each choice may affect subsequent steps in the process, it is important to consider the entire process. Many successful techniques have been developed by the research groups that have constructed specialised detectors for the requirements of their research. These techniques can generally be extended to the construction of other detectors. Information on design, materials selection, and construction techniques which have proved to be useful in the construction of a wide variety of detectors is presented.

Large-window gas proportional scintillation counter with photosensor compensation

New methods are presented that allow the design of non-focused gas proportional scintillation counters (GPSC) with window areas that approximate the photomultiplier window area. These methods are alternatives to a previously reported technique that uses a non-uniform electric field produced by a curved grid to compensate for the radial decrease of the scintillation light collected in the photosensor due to solid angle and reflection effects. The present work reverts to a uniform electric field and compensation is achieved with a mask with a radially-decreasing density of opaque dots that are deposited onto the window of the photosensor. The variation in the density of opaque dots is calculated to produce radially-independent light collection in the photosensor. An implementation of this new design is presented for a 52-mm-diameter photomultiplier tube with a 46-mm-effective diameter. The variation in pulse amplitude as a function of radial position was observed to be reduced from 18% to only 3.5% over the area contained within the central 19 mm radius. For a 38-mm-diameter window, the energy resolution for 5.9 keV X-rays was improved from 18% to 10% with the addition of the compensating mask.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A scintillation detector of unique geometry

A scintillation detector meeting specific physics requirements and geometrical constraints is described. It operates with high efficiency inside a 1 T magnet in an intense charged particle beam of up to 3 × 10 6 particles/s. It uses a unique light collection system combining air space, wavelength shifter disc and conventional lucite light guides. The detector is used in a veto mode to identify interactions that produce an all-neutral final state. The details of the counter's design, construction and performance are described.

Parallel counter implementation

An (n, m) parallel counter is a circuit withn inputs that produces anm-bit binary count of the number of its inputs that are ONEs. This article reports on the design of large parallel counters with up to 1023 inputs. Design trade-offs are examined regarding the use of counter cells of size ranging from (3,2) to (31,5) as building blocks.

Muon trigger counters for a hadron collider experiment

We describe the design and performance of prototype trigger counters for the SDC muon system. The 1.0×48.7×178.7 cm scintillation counters feature compact light guides, use standard 2 in. phototubes, and provide good photoelectron yields (>25) and time resolution (< 1 ns).

Precision time counter for laser ranging to satellites

A new design of the precision time counter for satellite laser ranging is described. The instrument features 3 ps incremental resolution within the measuring range up to 21.47 s, the short-term rms error below 30 ps, and the time drift within ±5 ps. To reject unwanted noise and other disturbing signals the programmable window discriminator has been employed. In order to achieve high accuracy and good long-term stability we used an automatic calibration based on the adaptive prediction. Further significant reduction of the measurement error has been achieved by self-correction of the nonlinearity error and robust estimation. Results from experimental tests are presented to demonstrate the performance of the instrument.

Optical design of a beam Cherenkov counter: chromatic corrections

Calculations of chromatic corrections and design of chromatic corrections are discussed. Application to the case of the new beam-RICH counter HYPOLIT is described.

A high resolution fast-RICH counter for on-line tagging of high energy particles

The design and performances of a new Cherenkov counter for on-line tagging of high energy particles are reported. The counter is equipped with a 6 m focal length spherical mirror and a chromatic corrector. The Cherenkov ring size is reduced by means of a set of two conical mirrors to match the active area of an image intensifier which output is read by a matrix of optical fibres partitioned in pixel, each pixels being coupled to a photomultiplier. Results of tests with π (plus K and p ) beams are reported and performances of the apparatus are discussed. A spatial resolution of 0.125 mm (20.6 μrad angular) on the Cherenkov radius measurement has been obtained with a 50 μrad divergence 220 GeV pion beam, outlining encouraging prospects for a separation of 270 GeV Σ − and Ξ − hyperons at the 5σ level.

Design and analysis of delay-insensitive modulo-N counters

Various delay-insensitive circuits for modulo-N counters are formally derived and analyzed. Modulo-N counters are used in many circuit designs and have a simple specification, but allow for a surprising variety of decompositions into networks of basic components. We present three decompositions in detail. Along the way we explai our correctness criteria and show to analyze the area complexity and response time of each decomposition. Our final decomposition for the modulo-N counter has optimal area complexity of θ(logN) and optimal response time of θ(1).

The luminosity monitor of Beijing spectrometer

A luminosity monitor (LM) was constructed at Beijing Electron Positron Collider (BEPC) responsible for measuring the colliding luminosity of BEPC. Being a part of the Beijing spectrometer (BES), which is a large major detector of the BEPC, the LM is also capable of providing the integrated luminosity for physics study in BES. By various means, such as fine design and careful manufacture of various counters, precise positioning of the LM, employing multifold and delay coincidences, etc., the LM is able to measure a relatively precise luminosity with a significantly suppressed background, e.g. the first colliding of BEPC in 1988 was detected and announced in time by the LM with a luminosity of 5 × 10 28/cm 2 s. Besides, some useful information was provided by the LM to assist the proper operation of the BEPC. In this paper, the construction, operation, experimental results and the error analysis of the LM are presented in detail.

New concepts for the design of large area gas proportional scintillation counters

New concepts are presented that allow the design of gas proportional scintillation counters with the large areas and medium-size photomultipliers. These designs are based on the compensation of the radial decrease of the scintillation light collected in the photomultiplier due to solid angle and reflection effects, with a radial increase of the light production due to a nonuniform electric field produced by a properly shaped curved grid. An implementation of these concepts based on a 2-in-diameter photomultiplier is presented. It shows a pulse amplitude variation along the radial position (0 to 10 mm) of less than 0.5%, and an energy resolution of 8.0% for a broad 5.9-keV X-ray beam entering the detector through the full 25-mm-diameter window.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The use of multiwire proportional counters in a cosmic ray air shower experiment

We discuss the design and performance of multiwire proportional counters working as “proportional mode counters”. An array of 511 of these counters was used to record the densities of particles near to the core of PeV air showers.

Designing high-performance digital circuits using wave pipelining: algorithms and practical experiences

Algorithms to automatically realize delays in combinational logic circuits to achieve wave pipelining are presented. The algorithms adjust gate speeds and insert a minimal number of active delay elements to balance input-output path lengths in a circuit. For both normal and wave-pipelined circuits, the algorithms also optimally minimize power under delay constraints. The authors analyze the algorithms and comment on their implementation. They report experimental results, including the design and testing of a 63-bit population counter in CML bipolar technology. A brief analysis of circuit technologies shows that CML and super-buffered ECL without stacked structures are well suited for wave pipelining because they have uniform delay. Static CMOS and ordinary ECL including stacked structures and emitter-followers do have some delay variations. A high degree of wave pipelining is still possible in those technologies if special design techniques are followed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Bit-serial architecture for optical computing

The design of a complete, stored-program digital optical computer is described. A fully functional, proof-of-principle prototype can be achieved by using LiNbO(3) directional couplers as logic elements and fiber-optic delay lines as memory elements. The key design issues are computation in a realm where propagation delays are much greater than logic delays and implementation of circuits without fip-flops. The techniques developed to address these issues yield architectures that do not change as their clocking speed is scaled upward and the size is scaled downward proportionally; these are called speed-scalable architectures. Signal amplitude restoration and resynchronization are accomplished by the novel technique of switching in a fresh copy of the system clock. Device characteristics that are important to the proof-of-principle demonstration are discussed, including the special properties and limitations that are important when designing with them. Design principles are exemplified by the design of an n-bit counter. Following this, the design for a stored-program bit-serial computer is described. We estimate that the described prototype architecture can be operated in the 100-MHz region with off-the-shelf components, and in the O. 1-1-THz region with foreseeable future components.

A silicon pad counter for first level triggering in ultrarelativistic proton-nucleus and nucleus-nucleus collisions

The CERES/NA45 experiment at CERN uses a silicon pad detector with 64 ring shaped pads for first level triggering on minimum bias proton-nucleus as well as on high multiplicity ion-ion collisions. In addition, the counter serves as a multiplicity detector to estimate the energy density obtained in the collision. The design and performance of the pad counter in the laboratory and under real beam conditions together with the first level trigger electronics are reported.

Design and calibration of a new optical plankton counter capable of sizing small zooplankton

A new design of optical plankton counter (OPC) capable of sizing zooplankton in the size range of 256μ to 2 cm is presented. The detection sensitivity is the result of new optical design of the previous system ( Herman, 1988, Continental Shelf Research, 8, 205–221) that originally had a lower detection limit of 550 μm. Both theoretical and experimental calibrations for the OPC are derived and compared. Preserved copepods and eggs introduced in a flow tank demonstrate the response of the OPC and its capability for detecting plankton to a limit of 250 μm. Copepod profiles measured by the OPC mounted on plankton net samplers provided intercomparisons that showed good agreement in identifying copepod layers and identifying some species, for example, copepods as small as Calanus finmarchicus II and up to the adult stages. Profiles containing marine snow and Ceratium illustrate some of the limitations of the OPC in directly measuring and identifying copepods. An additional modification to the OPC may result in a potential lower limit detection of 120 μm, and the practicality of such applications are discussed.

100-MHz optical counter that uses directional coupler switches

We have constructed what is to our knowledge the first speed-of-light 100-MHz digital optical counter using directional coupler switches and single-mode fibers. The counter has operated with both 4- and 6-bit counts, with the use of two different counter designs. In addition, we have demonstrated operation of two simultaneous and independent 4-bit counters running on the same hardware by time-division multiplexing the hardware. This approach allows effective clock rates many times the individual machine clock rate and is limited only by the switching speed. For large latency systems, this approach offers the promise of gigahertz clock rates for digital optical computers.

The use and development of ring-imaging Cherenkov counters

The present status of four major fixed-target experiments E789 and E665 at FNAL and WA89 and NA45 at CERN that use RICH (ring-imaging Cherenkov) counters is reviewed. The flexibility in adapting the basic RICH counter design to different outer geometrical constraints is discussed. It is noted that the design rules for the layout of a RICH counter allow for considerable flexibility and that it is possible to adapt the geometry of a RICH counter to a number of experimental constraints. This is of specific importance in colliding-beam experiments, where such constraints tend to be severe. As an example of the ongoing generic development of the RICH method, the recent discovery of a high-quantum-efficiency, air-resistant CsI-TMAE photocathode is reported. >

Aerosol climatology measurements with a Nolan-Pollak counter

Abstract The Nolan-Pollak photoelectric nucleus counter was originally developed in the 1940s for aerosol climatology measurements although its versatility led subsequently to many other applications in aerosol science. It has been widely used in manual, automatic and modified forms in many parts of the world to record ambient concentraions of Aitken nuclei. The design, calibration and performance of an automatic counter is described. Measurements of Aitken nuclei at Mace Head, Ireland, are used to discuss its suitability for the purpose of aerosol climatology.