Track Counting Research Articles

Temporal and spatial study of neon ion emission from a plasma focus device

The temporal and spatial characteristics of the neon ion beam emissions from a low energy plasma focus device have been studied by employing a multiple Faraday cup assembly and the CR-39 track detectors at different angular and axial positions. In addition, the operating gas pressures were also varied to study the temporal and spatial characteristics of the neon ion beam emissions. The Faraday cup analyses show that the ion flux strongly depends on the operating gas pressure as well as the angular positions. The estimated ion energy measurements at the aperture of the Faraday cup indicate that the plasma focus device is a source of polyenergetic ions ranging from approximately a few keV to a few hundreds of keV, irrespective of the angular positions. The exposed CR-39 detectors have shown the formation of multiple ion tracks with diameter ranging from 2 to 13 μm. The populations of lower diameter tracks (2–6 μm) are observed to be more at 0° and 10° angles. It is also noticed that the most populated track counts have shifted toward the higher diameter as the angular positions change from 0° to 70°. The present study enables us to predict a clear picture of ion flux and energy distribution inside the plasma focus chamber that will help to use the device for material irradiation application in a more controlled manner.

Identification and counting of alpha tracks by using an imaging plate

Based on the imaging plate (IP) techniques and taken the overlapping as well as fading effects into account, a new track counting method for alpha particles was developed and testified in this study. A photostimulated luminescence (PSL) value of 0.25 was supposed as a reasonable threshold for discriminating alpha particles from beta and natural background radiation. Compared with the previous method (PSL value method), it was found that the new method had a better linearity and a lower detection limit for measurements of alpha radiation, and the fading effect on the discrimination was also smaller.

Influence of variation of etching conditions on the sensitivity of PADC detectors with a new evaluation method

At the Paul Scherrer Institut, a personal neutron dosimetry system based on chemically etched poly allyl diglycol carbonate (PADC) detectors and an automatic track counting (Autoscan 60) for neutron dose evaluations has been in routine use since 1998. Today, the hardware and the software of the Autoscan 60 are out of date, no spare components are available anymore and more sophisticated image-analysis systems are already developed. Therefore, a new evaluation system, the 'TASLIMAGE', was tested thoroughly in 2009 for linearity, reproducibility, influence of etching conditions and so forth, with the intention of replacing the Autoscan 60 in routine evaluations. The TASLIMAGE system is based on a microscope (high-quality Nikon optics) and an ultra-fast three-axis motorised control for scanning the detectors. In this paper, the TASLIMAGE system and its possibilities for neutron dose calculation are explained in more detail and the study of the influence of the variation of etching conditions on the sensitivity and background of the PADC detectors is described. The etching temperature and etching duration were varied, which showed that the etching conditions do not have a significant influence on the results of non-irradiated detectors. However, the sensitivity of irradiated detectors decreases by 5 % per 1°C when increasing the etching temperature. For the variation of the etching duration, the influence on the sensitivity of irradiated detectors is less pronounced.

Negative Pion Induced Fission with Heavy Target Nuclei

We investigate fission induced by negative pions in copper and bismuth targets using CR-39 dielectric track detectors. The target-detector assemblies in 4π-geometric configuration were exposed at the AGS facility of Brookhaven National Laboratory, USA. The exposed detectors were chemically etched under appropriate etching conditions and scanned to collect data in the form of fission fragments tracks produced as a result of interaction of pions with the target nuclei. Using the track counts, the experimental fission cross sections for copper and bismuth have been measured at energies of 500, 672, 1068 and 1665 MeV and compared with the calculation using the Cascade-Exciton Model code (CEM95). The values of fission probability based on experimental fission cross-sections have been compared with the theoretically calculated values of fission probabilities obtained using the CEM95 code. Good agreement is observed between the measured and computed results.

Is water the key? Dingo management, intraguild interactions and predator distribution around water points in arid Australia

Context Predators are major beneficiaries of artificial water points in arid environments, yet little is known of the effects of water on the distribution of many sympatric species. Intraguild interactions around water points in arid Australia may play a significant role in structuring mammalian predator assemblages and influence spatial predation on some native prey species. Aims We examined how management of an apex predator, the dingo (Canis lupus dingo), influenced the distribution of two introduced mesopredators, foxes (Vulpes vulpes) and feral cats (Felis catus), around water points in arid Australia. Methods The spatial activity of dingoes, foxes and feral cats was assessed at five study sites with varying dingo management regimes. Sampling of predator activity was monitored using track counts at measured proximity to water points. Key results At sites where dingoes were uncontrolled, foxes were less likely to be found within 5 km of water points; conversely, where dingoes were controlled using exclusion fencing, fox activity was highest near water. Where dingo activity was reduced using 1080 baiting, feral cats were found closer to water. Conclusions These patterns suggest that the presence of dingoes instigates avoidance behaviour by foxes and feral cats, and through doing so may limit the use of artificial waters by these mesopredators. Through limiting access to such an essential resource in arid environments, dingoes may reduce mesopredator populations and minimise their impact on native prey. Implications For the conservation of native biodiversity, it may prove beneficial to maintain intact dingo populations due to their suppressive effect on mesopredators.

Effect of serialized routing resources on the implementation area of datapath circuits on FPGAS

In this work, we investigate the effect of serialization on the implementation area of datapath circuits on FPGAs. With ever-increasing logic capacity, FPGAs are being increasingly used to implement large datapath circuits. Since datapath circuits are designed to process multiple-bit wide data, FPGA routing resources, which typically consist of a significant amount of FPGA area, are routinely being used to transport multiple-bit wide signals. Consequently, it is important to design efficient routing architectures for transporting multiple-bit wide signals on FPGAs. Serialization, where several bits of a signal are first time-multiplexed and then transported over a single wire, has been effectively used to increase the I/O bandwidth of FPGAs. Recent work has proposed to use serialization to increase the area efficiency of FPGA routing resources for transporting multiple-bit wide signals. Most of the work, however, has focused on circuit-level design issues. Little work has been done on the overall effect of serialization on the area efficiency of FPGAs. In this work, we investigate the overall effect of serialization on the area efficiency of FPGAs. We propose a detailed FPGA routing architecture, which contains a set of serialization routing resources, and its associated routing tool. Using the architecture and the tool, we measure the effect of serialization on active area and track count. We found that, for benchmarks that contain four-bit wide datapath circuits, serialization can achieve a maximum active area reduction of 6.4% and a routing track reduction of 29%.

Effectiveness of Wildlife Underpasses and Fencing to Reduce Wildlife‐Vehicle Collisions

ABSTRACT Transportation planners are increasingly incorporating roadway design features to mitigate impacts of highways on wildlife and to increase driver safety. We used camera and track surveys to evaluate wildlife use before and after construction of 3 wildlife underpasses and associated fencing on a new section of United States Highway 64 in Washington County, North Carolina, USA. We recorded 242 occasions of white‐tailed deer (Odocoileus virginianus) use of underpass areas before highway construction began. Following completion of the highway, we collected 2,433 photographs of 9 species with deer representing 93% of all crossings. Adjusting for differences in number of monitoring days, white‐tailed deer use of underpass areas averaged 6.7 times greater after the new highway and underpasses were completed. We recorded 3,614 wildlife crossings of ≥20 species based on track counts, representing most medium and large mammals known to occur in the area and several reptiles and birds. After completion of the highway, we documented wildlife mortality due to vehicle collisions during a 13‐month period and recorded 128 incidences representing ≥24 species. Within fenced highway segments, mortalities were lowest near underpasses and increased with distance from the underpasses. However, we also documented more mortalities in fenced areas compared with unfenced areas. With greater distance from an underpass, animals with smaller home ranges seemed less likely to reach the underpass and instead attempted to climb over or crawl under fencing. Based on collision reports from adjacent highway sections, the new section of United States Highway 64 experienced approximately 58% fewer wildlife mortalities (primarily white‐tailed deer), suggesting underpasses and fencing reduced the number of deer‐vehicle collisions. Continuous fencing between underpasses may further reduce the number of vehicle collisions for deer but additional design features (e.g., buried fencing) should be considered for other wildlife species.

Saline versus Saline with Blood as a Contrast Agent for Right‐to‐left Shunt Diagnosis by Transcranial Doppler: Is There a Significant Difference?

Agitated saline solution (AS) is the contrast agent (CA) of choice for the diagnosis of right-to-left shunt (RLS). The aim of this study was to compare AS to AS with blood (ASb) in the diagnosis and quantification of RLS by contrast-enhanced transcranial Doppler (cTCD). Forty-two patients were evaluated for RLS in both of the middle cerebral arteries (MCA) by cTCD. Both AS and ASb were used as CAs while the patient breathed spontaneously and during two different moments of a Valsalva maneuver. Embolus track (ET) counts were obtained from each MCA (MCA analysis) and from each patient (patient analysis). In the MCA analysis, at least one ET was identified in 109 (43.2%) of the AS tests and 136 (54%) of the ASb tests (P= .016). The ET counts were higher with ASb (78.0 ± 117.6) than with AS alone (46.9 ± 66.7; P= .01). In the patient analysis, at least one ET was identified in 62 (49.2%) of the AS tests and 77 (61.1%) of the ASb tests (P= .057). Similar ET counts were generated with both CA solutions. These findings support the inclusion of ASb as an option for RLS diagnosis in selected patients.

Neutron dosimetry device using PADC nuclear track detectors

A device consisting of poly allyl diglycol carbonate (PADC) foils with a polyethylene and polyvinyl chloride (PVC) radiator was calibrated in order to perform the dosimetry of an 241Am-Be source covering a dose range from 0 to 3.1 mSv. Working conditions were established for a good visualization and counting of tracks: chemical attack was made in two steps with different solutions and etching times. A good fit was obtained for the dose as a function of the number of tracks per unit surface area. The calculated decision threshold was 0.12 mSv.

Spatial frequency analysis of fluorescent nuclear track detectors irradiated in mixed neutron–photon fields

Abstract A new image processing method for the dosimetry of mixed neutron–photon fields using fluorescent nuclear track detectors (FNTDs) is investigated. Images obtained from FNTDs were processed using spatial frequency analysis to determine doses for both low and high LET radiations. Spatial frequency analysis extended the dynamic range of detectible neutron doses from 4 orders of magnitude for track counting only to at least 6 orders of magnitude by combining track counting with the new image processing method. Two different converters of indirectly ionizing radiation to secondary charged particles were used in conjunction with image processing to separate signals induced by neutron and gamma fields.

Online monitoring of particle mass flow rate in bottom spray fluid bed coating—Development and application

The primary purpose of this study is to develop a visiometric process analyzer for online monitoring of particle mass flow rate in the bottom spray fluid bed coating process. The secondary purpose is to investigate the influences of partition gap and air accelerator insert size on particle mass flow rate using the developed visiometric process analyzer. Particle movement in the region between the product chamber and partition column was captured using a high speed camera. Mean particle velocity and number of particles in the images were determined by particle image velocimetry and morphological image processing method respectively. Mass flow rate was calculated using particle velocity, number of particles in the images, particle density and size information. Particle velocity and number findings were validated using image tracking and manual particle counting techniques respectively. Validation experiments showed that the proposed method was accurate. Partition gap was found to influence particle mass flow rate by limiting the rate of solids flux into the partition column; the air accelerator insert was found to influence particle mass flow rate by a Venturi effect. Partition gap and air accelerator insert diameter needed to be adjusted accordingly in relation to the other variability sources and diameter of coating cores respectively. The potential, challenges and possible solutions of the proposed visiometric process analyzer were further discussed.

Practical consequences for the use of a personal dosemeter for fast neutrons at high-energy accelerators based on PADC detectors exposed up to one year

Abstract Since 1998, Paul Scherrer Institut has employed the routine use of a personal neutron dosimetry system based on chemically etched PADC (poly allyl diglycol carbonate) detectors and automatic track counting. In 2004, a new concept for individual monitoring at high-energy accelerators was implemented. In this concept the photon dosemeter of a combined photon/neutron dosemeter is evaluated monthly. The neutron dosemeter is only evaluated if the personal photon dose exceeds 2 mSv, or if the exposition period of the neutron dosemeter exceeds one year. Significant consequences for the evaluation of the neutron dosemeter in the dosimetry service were evidenced in the new concept. The wearing period of the neutron dosemeter can range from 1 to 12 months, potentially longer. Therefore, the long-term behavior of background track density and variation of response to Am–Be within 17 months was studied. The effects of “fading” and “aging” that influence the response of PADC detectors are determined. The application of an algorithm for neutron dose calculation takes into account long-term behavior and is described. Furthermore, repeated field calibrations were performed at the CERN-EU high-energy reference field (CERF) facility.

Assessment of multi-hypothesis tracking performance for low signal-to-noise ratio targets

The Multi-Hypothesis Tracker (MHT) is generally considered to be the best performing conventional tracker. It assesses the feasible association of sequences of measurements, calculates the probabilities of the association hypotheses and has track initiation capability. Whilst conventional tracking systems use a detection algorithm to extract measurements from the sensor data, Track-Before-Detect techniques remove the detection algorithm and supply all information received from the signal processing system as measurements to be associated and filtered by the tracker. We compare the performance of the MHT with that of a grid-based Hidden Markov Model Track-Before-Detect algorithm for low signal-to-noise ratio targets. The performances of the MHT and grid Hidden Markov Model algorithms are quantified using six measures: root-mean-square position error, overall detection probability, instantaneous detection probability, false track count, false track length, and computation resource. The grid Hidden Markov Model algorithm is found to have better detection and significantly better false track performance at the cost of computation resource. References S. S. Blackman and R. Popoli. Design and Analysis of Modern Tracking Systems. Artech House, 1999. B. Ristic, S. Arulampalam, and N. Gordon. Beyond the Kalman Filter: Particle Filters for Tracking Applications. Artech House, 2004. R. M. Burczewski and N. C. Mohanty. Detection of Moving Optical Objects. In Proceedings of International Telemetering Conference, pages 325--330, 1978. S. J. Davey, M. G. Rutten, and B. Cheung. Comparison of Detection Performance for Several Track-Before-Detect Algorithms. EURASIP Journal on Advances in Signal Processing, 2008. C. A. Barlow and S. S. Blackman. New Bayesian Track-Before-Detect Design and Performance Study. In Proceedings of SPIE 3373, 1998. L. D. Stone, C. A. Barlow, and T. L. Corwin. Bayesian Multiple Target Tracking. Artech House, 1999. S. B. Colegrove, S. J. Davey, and B. Cheung. Clutter Rejection Using Peak Curvature. IEEE Trans AES, 42:1492--1496, 2006. D. B. Reid. An Algorithm for Tracking Multiple Targets. IEEE Transactions on Automatic Control, AC-24:843--854, December 1979. B. Ristic and N. Gordon. Lecture notes in Multisensor and Data Fusion. Adelaide University, 2007. S. J. Davey, B. Cheung, and M. G. Rutten. Track-Before-Detect for Sensors with Complex Measurements. In Fusion Conference, 2009. S. J. Davey and M. G. Rutten. A Comparison of Three Algorithms for Tracking Dim Targets. In IDC Conference, 2007.

Road and Rail Side Vegetation Management Implications of Habitat Use by Moose Relative to Brush Cutting Season

Plants cut at different times produce resprouts that vary in their nutritional value relative to when they are cut. To determine how vegetation management in transportation (road and rail) corridors at different times of the year could influence browse quality in the years following cutting, and how this could potentially influence encounters between herbivores and vehicles, we undertook a 3-year study. In 2001, at a wildlife viewing area near Prince George, British Columbia, Canada, we established a control area and treatment areas where shrubs and trees that are used as food by moose (Alces alces) were cut at the beginning of June, July, August, September, and October. In the fall, moose were most often observed browsing the resprouts of plants cut in August (years 1 and 2 post-treatment) and September (year 3). Cumulative winter track counts were highest in the uncut control area in the years following cutting. Spring pellet counts revealed that most pellets were deposited in the uncut (years 1 and 2) and August-cut (year 3) areas during winter. With the exception of the first year after cutting, browse removal by moose was highest for plants cut later in the growing season. Overall, our findings suggest that following cutting, plants cut later in the year are selected more often by moose relative to those cut earlier. To reduce browse use of corridor vegetation in areas where concerns for moose-vehicle collisions exist, we recommend that vegetation maintenance activities be conducted in the early summer months of June and July.

Evaluation of Efficiency Calibration Parameters of the LR-115 Radon Detector

Measurement of 222Rn is an important research concern because of the high-energy alpha emission of its 218Po and 214Po progeny. The LR-115 passive detector is the basis of a solid-state nuclear track detector (SSNTD) whose use for radon measurements has been well established. The usage of the SSNTD technique requires calibration by comparison. The aim of this work is to evaluate the efficiency calibration parameters for the radon measurement system that three steps: (1) irradiation conditions, (2) etching conditions, and (3) track counting. The following parameters were evaluated: breakdown and counting voltages for the spark counter, detector thickness, etching time, temperature and NaOH concentration as etching conditions for the LR-115 detector. Calibrating factors of 0.035 and 0.028 tracks cm-2 Bq-1 m3 d-1 for the open- and closed-chamber radon monitors, respectively, were determined considering the best efficiency calibration parameter values.

Substrate and species constraints on the use of track incidences to estimate African large carnivore abundance

Population size and trends of large carnivores are difficult to determine, but are often needed to inform conservation actions. Direct counts maintained over long time periods are extremely difficult to achieve. Indices of population sizes can be used to estimate large carnivore abundances, but are often case-, species- and site-specific. Here, we test the general applicability of track-based indices to estimate large carnivore abundance. We surveyed 15 306.4 km of roads associated with 339 transects across a wide geographical scale, large range of densities and variable substrates for tracks of African large carnivores. A combined model for all carnivore species on sandy soils serves as a robust approach to predict large carnivore densities. Thus, indices based on track counts can provide useful estimates of carnivore abundance. We found consistent relationships between track densities and the actual carnivore densities, having taken account of substrate.

Novel fluorescent nuclear track detector technology for mixed neutron-gamma fields

Abstract The latest achievements in fluorescent nuclear track detector (FNTD) technology are described. FNTDs are aluminum oxide crystals containing aggregate oxygen vacancy defects and doped with carbon and magnesium (Al 2 O 3 :C,Mg). Unlike most nuclear track detectors, Al 2 O 3 :C,Mg is sensitive to low linear energy transfer (LET) radiation including secondary electrons resulting from interactions of photons with the crystal. A new image processing method is investigated as a technique to discriminate and measure the doses of gamma and fast neutrons in mixed field conditions. Dose dependencies for both gamma and neutron irradiated FNTDs are shown. The new image processing method increased the dynamic range of detectable neutron doses from 4 orders of magnitude for track counting method to at least 6 orders of magnitude by combining track counting with the new image processing method. The new image processing method is combined with a detector configuration utilizing three converters: Teflon ® , polyethylene, and lithium fluoride.

Automatic Counting of Electrochemically Etched Tracks in Compact Discs. Application to Retrospective Measurements of Rn-222

This work describes an algorithm for automatic counting of alpha tracks in scanned images of electrochemically etched CDs and DVDs. It is demonstrated that the algorithm copes with the specific problems encountered in retrospective 222Rn measurements with CDs and DVDs; it reliably separates overlapping tracks and ignores artifacts in the image. The algorithm is validated by comparison to manual counting and a very good correlation is found. The measurement range of 222Rn concentrations in dwellings and soil gas is estimated. It is shown that the wide span of track densities that can be covered by the algorithm combined with the specific advantages of the compact disc method can provide reliable measurements in the whole range of 222Rn concentrations of practical interest. For retrospective measurements of 222Rn in dwellings the estimated range is from 10 Bq/m3 to 100 kBq/m3 for five years exposure time. For 222Rn in soil gas the estimated range is from 1 kBq/m3 to 10 MBq/m3 for ten days exposure time.

Effects of Building a Highway and Wildlife Crossings in a Red Deer (Cervus elaphus) Habitat in Hungary

We examined how the movement of red deer (Cervus elaphus) was modified in an area that had a new fenced off highway built across it. The first step was the collection of data from the track marked for construction. We continued collecting data on wildlife crossings after the construction of the highway and the completion of the fences. After the completion of the highway, it was observed that only 5.9% of the original deer track counts remained, spread across the crossings. After the construction was finished, the wider crossing structures were used more often by deer for crossing to the other side of the highway than the smaller ones. During construction of the highway, a number of animals chose to walk tens of kilometres to get around the construction site instead of using the crossings. An existing highway, or a highway under construction not only changes the frequency of deer crossings, but affects their distribution as well.

Factors affecting the registration and counting of alpha tracks in solid state nuclear track detectors

In view of the fact that the radon progeny contribute the highest to the natural radiation dose to general populations, large scale and long-term measurements of radon and its progeny in the houses have been receiving considerable attention. Solid State Nuclear Track Detector (SSNTD) based systems, being the best suited for large scale passive monitoring, have been widely used for the radon gas (using a cup closed with a semi-permeable membrane) and to a limited extent, for the measurement of radon progeny (using bare mode in conjunction with the cup). These have been employed for radon mapping and indoor radon epidemiological studies with good results. In this technique, alpha tracks recorded on SSNTD films are converted to radon/thoron concentrations using corresponding conversion factors obtained from calibration experiments carried out in controlled environments.The detector response to alpha particles depends mainly on the registration efficiency of the alpha tracks on the detector films and the subsequent counting efficiency. While the former depends on the exposure design, the latter depends on the protocols followed for developing and counting of the tracks. The paper discusses on parameters like etchant temperature, stirring of the etchant and duration of etching and their influence on the etching rates on LR-115 films. Concept of break down thickness of the SSNTD film in spark counting technique is discussed with experimental results. Error estimates on measurement results as a function of background tracks of the films are also discussed in the paper.