Design Of Counter Research Articles

A time-of-flight measurement system for the HADES wide-aperture dielectron spectrometer

The HADES spectrometer and a time-of-flight detector based on long-sized (50–250 cm) scintillation counters are described. The detector is designed for identification of electrons, pions, and protons with momenta of 0.1–1.5 GeV/c at a flight distance of 220–250 cm. The operating conditions are analyzed, and the requirements to the detector and counter design are formulated. The design of the counters and their arrangement in the spectrometer are considered. The results of experimental studies of such characteristics of long counters as the light attenuation length in a scintillator and temporal and spatial resolutions, dependeing on the location of the point of the particle’s hit on the counter, are presented. Analysis of the data has shown that the main factor determining the spatial resolution of long counters is the quality of the polishing of the side faces of the scintillators, which determines the effective (averaged over the scintillator side surfaces) coefficient of total internal reflectionR. It is shown that, forR>-0.99, it is quite possible to achieve temporal and spatial resolutions of 100 ns and 2–3 cm, respectively, for scintillators with a length of up to 250 cm and a cross section of 1–20 cm2. Foreign and Russian photomultipliers were used in the counters.

A wide-aperture Cerenkov counter with a water radiator

The design of a Cerenkov counter with a water radiator (200×400 mm), containing a wavelength shifter, is described. The counter was used for π- andK-meson selection in a positive-particle beam with 250–1000-MeV/c momentum.

Automated constraint-based nucleotide sequence selection for DNA computation

We present techniques for automating the design of computational systems built using DNA, given a set of high-level constraints on the desired behavior and performance of the system. We have developed a program called scan that exploits a previously implemented computational melting temperature primitive to search a ‘nucleotide space’ for sequences satisfying a pre-specified set of constraints, including hybridization discrimination, primer 5′ end and 3′ end stability, secondary structure reduction, and prevention of oligonucleotide dimer formation. The first version of scan utilized 24 h of computer time to search a space of over 7.5 billion unary counter designs and found only nine designs satisfying all of the pre-specified constraints. One of scan’s designs has been implemented in the laboratory and has shown a marked improvement in performance over the products of previous attempts at manual design. We conclude with some novel ideas for improving the overall speed of the program that offer the promise of an efficient method for selecting optimal nucleotide sequences in an automated fashion.

Low-background /sup 3/He proportional counters for use in the Sudbury neutrino observatory

Current solar neutrino detectors measure a considerably lower flux of electron-flavor neutrinos than predicted by solar models. This could be an indication of neutrino oscillations, which would provide direct evidence that neutrinos have mass. The Sudbury Neutrino Observatory (SNO) was designed to detect all flavors of neutrinos, and will provide a rigorous test of this theory. The SNO detector's heavy water target gives it the unique ability to detect all non-sterile neutrino flavors via the neutral-current (NC) break-up of the deuteron. This NC interaction liberates a neutron which may be detected with an array of discrete /sup 3/He proportional counters. The strict radioactivity requirements imposed by the need for low backgrounds dictate the use of ultra-pure materials and processes in building these counters. Additionally, they must survive in the heavy water environment for several years. The design, construction, and testing of these unique counters are described.

Optics and radiators for RICH

An overview is given of the basic optics-design principles for Ring Imaging Cherenkov (RICH) counters in High-Energy Physics — of the earlier evolution of these principles and of the new ideas and techniques that are currently being developed. The characteristics of the different gasses, liquids and solids that are employed as Cherenkov radiators, which are of fundamental importance to the optics design of a RICH counter, are also reviewed.

Synchronous derived clock and synthesis of low power sequential circuits

Based on analyzing significance of controlling clock in design of low power sequential circuits, this paper proposes a technique that the gating signal is derived from the master latch in a flip-flop to make the derived clock having no glitch and no skew. The design of a decimal counter with half-frequency division shows that by using the synchronous derived clock the counter has lower power dissipation as well as simpler combinational logic. Computer simulation shows 20% power saving.

Neutron proportional counter design for high gamma-ray environments

A parametric analysis of the performance of 3He neutron proportional detector tubes in mixed gamma-ray/neutron environments has been performed. The objective of this study was to determine the optimum tube design configuration for minimized gamma-ray sensitivity based upon commercially available components. The parameters examined in the study were the tube wall material, the admix gas identity, the total fill pressure, and the tube lining material. The study resulted in the quantification of the limitations of typical 3He tube designs and in the development of a new tube design which extends the usefulness of 3He tubes in mixed gamma-ray/neutron environments.

Methods for neutral-current neutrino detection in the Sudbury neutrino observatory

The Sudbury Neutrino Observatory will permit a comparison of the rate of neutral-current neutrino interactions to charged-current interactions, which is a test of neutrino mixing and mass. The neutral-current process can be measured by: a) comparison of the rate for electron elastic scattering to the pure charged-current rate on deuterium, b) neutron capture on Cl ions added to the heavy water, and, c) neutron capture in an array of 3He-filled proportional counters. The design and construction of suitable proportional counters are described.

Designing asynchronous standby circuits for a low-power pager

We have designed asynchronous standby circuits for a pager decoder which dissipate four times less power and are 40% larger in size than synchronous designs. For the total pager unit this means a 37% reduction in power dissipation for nearly no additional area. The decoded chip, which apart from the standby circuits is completely synchronous, has been fabricated and was first-time-right. Two problems had to be solved to incorporate asynchronous subcircuits in a synchronous environment: synchronization and testing. A synchronization scheme is described that allows a free intermixing of asynchronous and synchronous modules and a test strategy is proposed in which the scan test facilities in the synchronous environment are used to test the asynchronous modules. One function is prevalent in the standby circuits, namely counting. In an appendix we present the asynchronous design of a so-called loadable counter whose power consumption does not depend on its size.

Energy Response of Tissue Equivalent Proportional Counter for Neutrons above 20 MeV

The calculation of energy dose and dose equivalent response of the tissue-equivalent proportional counter with low gas pressure for neutrons in the energy region from 20 MeV up to 5 GeV is carried out. The comparison between calculation and measurements in the radiation field at the top shielding of the IHEP accelerator is presented. The dependence of the TEPC neutron response and errors of the measured neutron dose equivalent on counter design and measurement methods are discussed.

Long and fast up/down counters

This paper presents recent advances in the design of constant-time up/down counters in the general context of fast counter design. An overview of existing techniques for the design of long and fast counters reveals several methods closely related to the design of fast adders, as well as some techniques that are only valid for counter design. The main idea behind the novel up/down counters is to recognize that the only extra difficulty with an up/down (vs. up-only or down-only) counter is when the counter changes direction from counting up to counting down (and vice-versa). For dealing with this difficulty, the new design uses a "shadow" register for storing the previous counter state. When counting only up or only down, the counter functions like a standard up-only or down-only constant time counter, but, when it changes direction instead of trying to compute the new value (which typically requires carry propagation), it simply uses the contents of the shadow register which contains the exact desired previous value. An alternative approach for restoring the previous state in constant time is to store the carry bits in a Carry/Borrow register.

Breakdown features of various microstrip-type gas counter designs and their improvements

Breakdown mechanisms and spurious pulses, the precursors to some breakdowns, were studied experimentally for both uncoated and coated microstrip gas counters (MSGCs) of different geometries, as well as for microgap counters (MGCs) and for the Compteur A Trou (CAT). It was found that in all cases the breakdowns occurred through surface streamers, although the exact mechanism of streamer formation depended on the particular detector design. Based on these studies, new designs of microstrip detectors, in which the role of the substrate was minimized, were elaborated and tested. In some of these detectors, especially with large pitches (>2 mm), gains up to 2-3/spl times/10/sup 5/ were achieved together with good rate characteristics. The ultimate gain limit in all geometries was still set by spark-inducing streamers which appeared at some critical charge density in the avalanche. To avoid this, and particularly to enhance the performance of small-pitch MSGCs, preamplification structures can be used. Utilizing a parallel plate avalanche chamber as a front end to an MSGC resulted in an overall gain of /spl sim/10/sup 6/, limited in this case only by charge saturation.

Four-layer aerogel Cherenkov counter

A 4-layer design of aerogel threshold counters using two refractive indices was suggested for the particle identification in the forward region of the BaBar detector. Three prototypes filled with the high quality aerogel produced in Novosibirsk were tested at T10 beam at CERN. Monte Carlo code was developed for the simulation of the light collection in aerogel counters. Monte Carlo results based on measured PTFE reflection coefficient and aerogel absorption and scattering lengths are in agreement with experiment.

Design of a fast neutron coincidence counter

Monte Carlo simulations were carried out to simulate the response of a boron-loaded plastic scintillator array. These detectors offer potential advantages compared to moderated 3He systems because of their fast response and high efficiency. Tallies were made of neutron capture probability as a function of time and the results were coupled to assay variance estimates to evaluate detector performance. Orders-of-magnitude reductions in count time relative to a 50% efficient thermal counter are possible, in principle, for high (α,n) samples.

A modern review of "Electronic computing circuits of the ENIAC"

Presents a review of this classic paper. The body of the paper is divided into five sections: general circuit design considerations; types of computing circuits; flip-flop and counter design; units of the ENIAC; and analysis of typical circuits. Each section is described in this review.

A compact gas Cherenkov detector with novel optics

We discuss the design and performance of a threshold Cherenkov counter for identification of charged hadrons. The radiator is pressurized gas, which is contained in thin-walled cylindrical modules. A mirror system of novel design transports Cherenkov photons to photomultiplier tubes. This system is compact, contains relatively little material, and has a large fraction of active volume. A prototype of a module designed for the proposed CLEO III detector has been studied using cosmic rays. Results from these studies show good agreement with a detailed Monte Carlo simulation of the module and indicate that it should achieve separation of pions and kaons at the 2.5σ–3.0σ level in the momentum range 0.8−2.8 GeV c . We predict performance for specific physics analyses using a GEANT-based simulation package.

Design and analysis of up-down counters

Several designs for an up-down N-counter are derived for any N > 0. The up-down N-counter has a simple specification, but allows many non-trivial, efficient implementations. All designs are represented by means of a CSP-like program and are analyzed with respect to area, response time, and power consumption. Our final design has optimal area of Θ( log N), a bounded response time, and a bounded power consumption.

Sequential lookahead method for digital counters

In the design of synchronous digital counters the carry chain which starts from the least significant digit determines the maximum clock speed. Various schemes for implementing the carry calculation have been proposed to minimise the time of that computation. The author describes a new technique which uses additional state bits to aid in the carry calculation. This is shown to give a useful increase in clock speed over conventional combinational logic based carry lookahead techniques. The technique is also applicable to general finite state machines.

Parametric optimization of neutron drum counter

We optimize the efficiency of neutron counter designs for 208-1 drums when counting totals neutrons by using MCNP. Design parameters, including the number of 3He tubes and the tube pitch, depth, and gas-fill pressure, were investigated. Both cylindrical and rectilinear geometries with and without cadmium liners were examined. Fission spectra from both 240Pu and 252Cf were modeled as isotropic point sources located in the geometric center of the detector cavities.

Design of Tissue-Equivalent Proportional Counters

This paper deals with those factors which are of importance in the design of tissue equivalent proportional counters. Basic physical processes in the transport of ions and electrons through gases are discussed, as well as electron avalanche, but only from simple classical approximations. Monte Carlo techniques are dealt with elsewhere in this volume. Emphasis is on practical design considerations, and therefore the importance of geometrical factors is considered in some detail, as is physical size. These design parameters are illustrated with some successful designs of both cylindrical and spherical types. Finally, some of the more exotic recent developments in proportional counters are illustrated.