Counting Detector Research Articles

Increasing the accuracy of loop detector counts using adaptive neural fuzzy inference system and genetic programming

ABSTRACTLoop detectors are devices that are most commonly used for obtaining data at intersections. Multiple detectors are usually required to monitor a location, and this reduces the accuracy of detectors for collecting traffic volumes. The purpose of this paper is to increase the accuracy of loop detector counts using Adaptive Neural Fuzzy Inference System (ANFIS) and Genetic Programming (GP) based on detector volume and occupancy. These methods do not need microscopic analysis and are easy to employ. Four approaches for one intersection are used in a case study. Results show that the models can improve intersection detector counts significantly. Results also show that ANFIS produces more accurate counts compared to regression and GP.

Применение метода Монте-Карло для повышения точности дозиметрического планирования радионуклидной терапии

Purpose: Development and clinical testing of methodology dosimetry planning of radionuclide therapy based on Monte Carlo simulation of radiation transfer process.
 Material and methods: The method of determination in absolute units of radiopharmaceutical (RP) activity accumulated in tumor lesions. The technique is based on scintigraphy syringe containing diagnostic RP activity, biplane patient scintigraphy after injection of the RP and determination of the RP accumulation when administered calculated using the Monte Carlo method for the absorption and scattering of radiation in the patient’s body and in the collimator of the gamma camera. Code MCNP Monte Carlo simulation was used. The layout of determination of the value of accumulated RP activity in the patient’s tumor site implies successive implementation of the following three steps.
 1. Scintigraphic images are obtained of the vial containing already known activity of the RP placed at the fixed source-to-collimator distance, following
 which estimation of the detector count rate within the specified region of interest of the vial image is undertaken.
 2. Therapeutic activity A0 is introduced in the patient’s body, scintigraphic examination of the patient is performed. Estimation of the detector count rate in the region where the tumor is located and the value of tissue background in the close enough vicinity to the tumor is performed using the tools for contouring the region of interest on the obtained planar image provided using the software imbedded in the scintigraphic equipment.
 3. Value of accumulated activity RP in the affected tumor is determined according to the correction factor which is calculated using Monte-Carlo method for specific clinical case for the geometry used in obtaining scintigraphic images which is identical to the conditions of measurement of activity in the vial and in the patient’s body. The technique has been tested in the study, with an injection of 30 MBq of 123I-MIBG child with neuroblastoma.
 Results: The level of accumulation of radiopharmaceutical in the tumor of the adrenal gland was 0.78 MBq, i.e. 2.6 % of the administered activity. This corresponds to literature data (average about 2.4 %) for scintigraphic studies of children with neuroblastomas. When using the known calculation method for analytical formula without the introduction of corrections for the absorption and scattering of radiation was obtained a result of 1.02 MBq, i.e. overestimation was 31 %.
 Conclusions: Introduction calculated by the Monte Carlo method for the absorption and scattering of radiation during scintigraphy patient can improve the accuracy of dosimetry planning of radionuclide therapy.

Feedback‐charging a metallic island

AbstractWe consider electronic transport through a single‐electron quantum dot that is tunnel‐coupled to an electronic lead and a metallic island. A background reservoir keeps the metallic island at a thermal state with the ambient temperature, while the charge accumulated on the island is reflected in a time‐dependent chemical potential. Without feedback, a current would flow through the system until the chemical potentials of island and lead are equilibrated. A feedback loop can be implemented by a quantum point contact detecting the dot state, classical processing of the result, and appropriate feedback actions on the electronic tunneling rates taken, with the objective to direct the current in a preferred direction. Since we directly take the detector counting statistics into account, this automatically includes measurement errors in the description. When mainly the rates are modified but hardly any energy is exchanged with the system, this feedback loop effectively implements a Maxwell demon, capable of transporting electrons against an electric bias and thereby charging the metallic island. Once the feedback protocol is stopped, the metallic island simply discharges. We find that a quantitative detector model may be useful for a realistic statistical description of feedback loops.Sketch of the model. The system (S) consists of a single‐electron transistor (SET) dot that can be occupied with at most a single electron. It is tunnel‐coupled to a lead (R) held at a fixed thermal equilibrium state and to a metallic island (L). The metallic island is held at a fixed temperature by an additional background reservoir (bg), with which it can exchange energy but no particles (shaded contact region). Its chemical potential would normally evolve until . A simple feedback loop can be implemented by measuring the state of the system with a quantum point contact (dt), classical signal processing (SP), and using the gate controls (GC) to obtain occupation‐dependent tunneling rates. With feedback active, it is possible to charge the island (). Expressions in brackets (green) denote abbreviations used in the paper.

Automatic Optimization of AMS with LabVIEW

ABSTRACTAccelerator systems designed for a wide variety of ion beam analysis (IBA) applications usually have a multitude of beamline components and long beam lines. In the use of these systems, beam optimization is especially important for attaining high-precision accelerator mass spectrometry (AMS) results. The optimization involves multiple parameters, dependencies between parameters, and multiple optimization targets. To improve the repeatability and reliability of AMS results, we have developed a profiling program for automatic beam optimization. In our implementation, the accelerator control parameters, measured beam currents, and AMS detector count rates are all stored in a real-time database. The profiling routine can scan any accelerator parameter and fetch from the database the profile of any measured quantity as a function of the parameter. The routine is usually used to scan over roughly 20 essential parameters of the system and setting them to the optimum values. Automatic optimization is fast, easy to use, robust to noise, and gives reproducible results. In addition, the graphical output in the form of current and count rate profiles is highly informative. Automatic optimization together with other improvements to the AMS setup have enabled us to push the precision of the system to better than 0.2%.

Radioactivity: Detection and Measurement

Detection and quantification of emitted radioactive particles such as alpha, beta or high energy gamma and X-rays from a contaminated sample or source can easily be achieved by using different qualitative and quantitative approaches. In contrast to qualitative approach, quantitative methods of radioactivity detection are widely used because of their potential to identify and detect high as well as low radioactivity levels with increased sensitivity and counting accuracy. Gamma /X-Ray spectroscopy, Alpha/r Beta counters, Scintillation detectors including GM counter and LSC detectors are the well-recognized quantitative methods employed for this purpose.

Method Of Solar Neutron Search With PAMELA Neutron Detector

This research is devoted to solar neutron search in the flux of the particles emitted by the Sun during solar flare by means of the neutron detector of the magnetic spectrometer PAMELA. The main objectives of our research were to study the background conditions in the Resurs-DK1 satellite orbit during the periods of quiet Sun and to develop the methods of solar neutron search in the flux of high-energy solar particles. The tasks of study were as the analysis of the neutron detector count rate during solar flares with possible generation of neutrons and the attempt to detect the stationary neutron flux from the Sun in weak flares. The analysis was carried out for 28 solar events when neutrons could be produced during the period from December 2006 till October 2015.

Performance of photoelectron spin polarimeters with continuous and pulsed sources: from storage rings to free electron lasers.

In this work the experimental uncertainties concerning electron spin polarization (SP) under various realistic measurement conditions are theoretically derived. The accuracy of the evaluation of the SP of the photoelectron current is analysed as a function of the detector parameters and specifications, as well as of the characteristics of the photoexcitation sources. In particular, the different behaviour of single counter or twin counter detectors when the intensity fluctuations of the source are considered have been addressed, leading to a new definition of the SP detector performance. The widely used parameter called the figure of merit is shown to be inadequate for describing the efficiency of SP polarimeters, especially when they are operated with time-structured excitation sources such as free-electron lasers. Numerical simulations have been performed and yield strong implications in the choice of the detecting instruments in spin-polarization experiments, that are constrained in a limited measurement time. Our results are therefore applied to the characteristics of a wide set of state-of-the-art spectroscopy facilities all over the world, and an efficiency diagram for SP experiments is derived. These results also define new mathematical instruments for handling the correct statistics of SP measurements in the presence of source intensity fluctuations.

Assessment of the Robustness of Signal Timing Plans in an Arterial Corridor Through Seasonal Variation of Traffic Flows

Arterial traffic signal systems, predominantly in the United States, deploy multiple signal timing plans to account for daily variability of traffic demand. Those types of traffic flow deviations should be anticipated when timing plans are designed and, therefore, serviced satisfactorily. When traffic flow patterns are no longer predictable, a predetermined time-of-day (TOD) plan may no longer be the optimal one. This research aimed to examine signal timing optimality by applying a method similar to the selection of a traffic responsive plan to recognize automatically the best timing plan suited to current traffic conditions. The proposed method attempted to determine whether the optimality of signal timing settings could have been effectively estimated when systematic detector counts of the major approach were available. The study used 4 months of data from field microwave detectors coupled with data of turning-movement counts obtained over several days. The findings show that TOD signal timing plans mainly depended on adequate data collection that best describes a specific set of traffic conditions. Thus, the designed plan was as optimal as the related traffic information was reliable, whereas a problem arose in the case of limited-availability and low-quality data. New technologies are capable of collecting and storing massive amounts of data. Even if the granularity of collected data is low, the data can be used to improve traffic performance (i.e., reduce corridor delay). This realization could be of particular importance to traffic agencies that have installed, or plan to install, new field devices.

Monte Carlo optimization of shielding for novel industrial free release measurement facility

Monte Carlo (MC) simulations were done for the optimization of shielding configuration of a novel industrial radionuclide-specific pre-selection free release measurement facility. The shielding is made from unique bricks of concrete with very low specific activity of natural radionuclides. The final configuration was selected as a compromise between shielding volume and the simulated 1461keV full-energy peak detector count rates of natural 40K.

The rarity of terrestrial gamma‐ray flashes: 2. RHESSI stacking analysis

AbstractWe searched for gamma‐ray emission from lightning using the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) satellite by identifying times when RHESSI was near over 2 million lightning discharges localized by the Worldwide Lightning Location Network (WWLLN). We then stacked together the gamma‐ray arrival times relative to the sferic times, correcting for light propagation time to the satellite. The resulting stacked gamma‐ray time profile is sensitive to an average level of gamma‐ray emission per lightning discharge far lower than what can be recognized above background for a single terrestrial gamma‐ray flash (TGF). The summed signal from presumed small, previously unknown TGFs simultaneous with WWLLN discharges is remarkably weak: for the region from 0 to 300 km beneath RHESSI's footprint, (6.2 ± 3.8) × 10−3 detector counts/discharge are measured, as opposed to a typical range of 12–50 detector counts for TGFs identified solely from the gamma‐ray signal. Under the assumption of a broken power law differential distribution of TGF intensities, we find that the index must harden dramatically or cut off just below the sensitivity limit of current satellites and that for most scenarios less than 1% of lightning can produce a TGF that belongs anywhere in the same distribution as those that are observable. For the minority of scenarios where more than a few percent of flashes produce a TGF, most of these “TGFs” are less than 10−4 of the luminosity of the faintest RHESSI TGFs and therefore closer to the luminosity of lightning stepped leaders. The rarity of TGFs holds not only for TGFs simultaneous with the sferic observed by WWLLN but also for any time within 10 ms of the sferic, allowing (for example) for the possibility that different events within the upward propagation of a negative leader in positive intracloud lightning triggered the TGF and WWLLN's detection.

Search for solar neutrons using the data of neutron detector of the PAMELA spectrometer

The study is devoted to the development of the technique for searching for neutrons of solar origin during solar flares using the neutron detector of the PAMELA magnetic spectrometer onboard the RESURS-DK1 satellite. The study of the neutron detector counting rates showed that it operates properly and background conditions are stable in the geomagnetic equator region. 27 solar events from December 2006 to September 2014 were analyzed. Some events contain indications of solar neutron detection. The final conclusion on the nature of these neutrons requires an increase in statistics; to this end, background conditions in polar regions should be analyzed to increase the observation interval.

Martin Moses Block

Martin Moses Block

Alternative metrics for spatially and temporally resolved ambient particle monitoring

Particle active surface area is regarded as an important alternative metric to correlate particle emissions to adverse health effects. We explore the use of a particle counter and a diffusion charger as a relatively simple means to measure spatiotemporally resolved particle concentrations over a wide region using a mobile platform. Although the scanning mobility particle sizer (SMPS) measurements provide particle size distributions (PSDs) that can be converted into many important metrics, this method is impractical to implement for a routine monitoring over a wide region. In this study, an alternative method and new metrics are introduced using the condensation particle counter (CPC) and electrical aerosol detector (EAD). While the CPC and EAD measure particle number (PN) and particle active surface area (PS) concentrations respectively, the ratio of PS/PN provides an additional information of particle size which is important for particle transport. PSDs measured by SMPS during ambient monitoring were used to verify the concept. The study found that alternative metrics (PN, PS, and PS/PN) can be used to monitor spatiotemporally resolved particle concentrations over a wide region.

On a new mechanism on [formula omitted]-ray attenuation strengthened by new data

Introduction We extended our previous detailed γ -ray attenuation measurements of 60Co γ rays in Pb and Fe to include also Cu, Hg, Al and H2O. Purpose To introduce a new mechanism on γ -ray attenuation in matter. Materials and methods 60Co radiation source, slices of the absorbers and a Geiger Muller detector counter in broad and thin beam geometries. Experiments We performed detailed measurements of the detected radiation versus the thickness of the absorber and in parallel Monte Carlo simulations for each experiment. Results Monte-Carlo calculations were in qualitative agreement with experiment but quantitatively predicted systematically more radiation at the target. We related the differences with the parameters Eγ and Zeff of the photoelectric absorption cross section which guided us to propose a new mechanism on the absorption of γ rays in matter. The γ radiation creates a huge number of electrons and ions passing through the absorber which form a steady state plasma condition increasing slightly the parameters Eb and Zeff of the lattice which in turn can increase measurably the photoelectric absorption thus restoring the agreement between Monte Carlo calculations and experiment. Conclusion Based on our large set of data which included absorbers in a wide range of Zeff we strengthened the need for a new mechanism on γ-ray absorption in matter.

An automated Monte-Carlo based method for the calculation of cascade summing factors

A versatile method has been developed to calculate cascade summing factorsfor use in quantitative gamma-spectrometry analysis procedures. The proposed method is based solely on Evaluated Nuclear Structure Data File (ENSDF) nuclear data, an X-ray energy library, and accurate efficiency characterisations for single detector counting geometries. The algorithm, which accounts for γ–γ, γ–X, γ–511 and γ–e− coincidences, can be applied to any design of gamma spectrometer and can be expanded to incorporate any number of nuclides. Efficiency characterisations can be derived from measured or mathematically modelled functions, and can accommodate both point and volumetric source types. The calculated results are shown to be consistent with an industry standard gamma-spectrometry software package. Additional benefits including calculation of cascade summing factorsfor all gamma and X-ray emissions, not just the major emission lines, are also highlighted.

SU‐F‐J‐09: Radioactive Seed Localization for Breast Lumpectomy ‐ Towards Optimization

Purpose:The aim of this work is to propose a method to optimize radioactive source localization (RSL) for non‐palpable breast cancer surgery. RSL is commonly used as a guiding technique during surgery for excision of non‐palpable tumors. A collimated hand‐held detector is used to localize radioactive sources implanted in tumors. Incisions made by the surgeon are based on maximum observed detector counts, and tumors are subsequently resected based on an arbitrary estimate of the counts expected at the surgical margin boundary. This work focuses on building a framework to predict detector counts expected throughout the procedure to improve surgical margins.Methods:A gamma detection system called the Neoprobe GDS was used for this work. The probe consists of a cesium zinc telluride crystal and a collimator. For this work, an I‐125 Best Medical model 2301 source was used. The source was placed in three different phantoms, a PMMA, a Breast (25%‐ glandular tissue/75%‐ adipose tissue) and a Breast (75‐25) phantom with a backscatter thickness of 6 cm. Counts detected by the probe were recorded with varying amounts of phantom thicknesses placed on top of the source. A calibration curve was generated using MATLAB based on the counts recorded for the calibration dataset acquired with the PMMA phantom.Results:The observed detector counts data used as the validation set was accurately predicted to within ±3.2%, ±6.9%, ±8.4% for the PMMA, Breast (75‐25), Breast (25–75) phantom respectively. The average difference between predicted and observed counts was −0.4%, 2.4%, 1.4% with a standard deviation of 1.2 %, 1.8%, 3.4% for the PMMA, Breast (75‐25), Breast (25–75) phantom respectively.Conclusion:The results of this work provide a basis for characterization of a detector used for RSL. Counts were predicted to within ±9% for three different phantoms without the application of a density correction factor.

Evaluation of Am–Li neutron spectra data for active well type neutron multiplicity measurements of uranium

Safeguarding nuclear material is an important and challenging task for the international community. One particular safeguards technique commonly used for uranium assay is active neutron correlation counting. This technique involves irradiating unused uranium with (α, n) neutrons from an Am–Li source and recording the resultant neutron pulse signal which includes induced fission neutrons. Although this non-destructive technique is widely employed in safeguards applications, the neutron energy spectra from an Am–Li sources is not well known. Several measurements over the past few decades have been made to characterize this spectrum; however, little work has been done comparing the measured and theoretical spectra of various Am–Li sources to each other. This paper examines fourteen different Am–Li spectra, focusing on how these spectra affect simulated neutron multiplicity results using the code Monte Carlo N-Particle eXtended (MCNPX). Two measurement and simulation campaigns were completed using Active Well Coincidence Counter (AWCC) detectors and uranium standards of varying enrichment. The results of this work indicate that for standard AWCC measurements, the fourteen Am–Li spectra produce similar doubles and triples count rates. The singles count rates varied by as much as 20% between the different spectra, although they are usually not used in quantitative analysis, being dominated by scattering which is highly dependent on item placement.

A cylindrically symmetric "micro-Mott" electron polarimeter.

A small, novel, cylindrically symmetric Mott electron polarimeter is described. The effective Sherman function, Seff, or analyzing power, for 20 kV Au target bias with a 1.3 keV energy loss window is 0.16 ± 0.01, where uncertainty in the measurement is due primarily to uncertainty in the incident electron polarization. For an energy loss window of 0.5 keV, Seff reaches its maximum value of 0.24 ± 0.02. The device's maximum efficiency, I/Io, defined as the detected count rate divided by the incident particle rate, is 3.7 ± 0.2 × 10(-4) at 20 keV. The figure-of-merit of the device, η, is defined as Seff (2)IIo and equals 9.0 ± 1.6 × 10(-6). Potential sources of false asymmetries due to detector electronic asymmetry and beam misalignment have been investigated. The new polarimeter's performance is compared to published results for similar compact retarding-field Mott polarimeters, and it is concluded that this device has a relatively large Seff and low efficiency. SIMION(®) electron trajectory simulations and Sherman function calculations are presented to explain the differences in performance between this device and previous designs. This design has an Seff that is insensitive to spatial beam fluctuations and, for an energy loss window >0.5 keV, negligible background due to spurious ion and X-ray production at the target.

Characterization of a 6×6-mm2 75-μm cell MPPC suitable for the Cherenkov Telescope Array project

This paper presents the latest characterization results of a novel Low Cross-Talk (LCT) large-area (6×6-mm2) Multi-Pixel Photon Counter (MPPC) detector manufactured by Hamamatsu, belonging to the recent LCT5 family and achieving a fill-factor enhancement and cross-talk reduction. In addition, the newly adopted resin coating is demonstrated to yield improved photon detection capabilities in the 290–350nm spectral range, making the new LCT MPPC particularly suitable for emerging applications like Cherenkov Telescopes. For a 3×3-mm2 version of the new MPPC under test, a comparative analysis of the large pixel pitch (75-µm) detector versus the smaller pixel pitch (50-µm) detector is also undertaken. Furthermore, measurements of the 6×6-mm2 MPPC response versus the angle of incidence are provided for the characterized device.

Using stop bar detector information to determine turning movement proportions in shared lanes

SummaryTurning vehicle volumes at signalized intersections are critical inputs for various transportation studies such as level of service, signal timing, and traffic safety analysis. There are various types of detectors installed at signalized intersections for control and operation. These detectors have the potential of producing volume estimates. However, it is quite a challenge to use such detectors for conducting turning movement counts in shared lanes. The purpose of this paper was to provide three methods to estimate turning movement proportions in shared lanes. These methods are characterized as flow characteristics (FC), volume and queue (VQ) length, and network equilibrium (NE). FC and VQ methods are based on the geometry of an intersection and behavior of drivers. The NE method does not depend on these factors and is purely based on detector counts from the study intersection and the downstream intersection. These methods were tested using regression and genetic programming (GP). It was found that the hourly average error ranged between 4 and 27% using linear regression and 1 to 15% using GP. A general conclusion was that the proposed methods have the potential of being applied to locations where appropriate detectors are installed for obtaining the required data. Copyright © 2016 John Wiley & Sons, Ltd.