High Track Density Research Articles

Disturbance‐related redistribution of western capercaillie Tetrao urogallus away from woodland tracks

Wild vertebrates usually avoid ground disturbed by humans with uncertain effects on their distribution and density. We report on a natural experiment that confirms and extends previous conclusions about how the local distribution of capercaillie is affected by track‐based disturbance. We surveyed the birds' droppings in two periods, before and after a predicted increase in disturbance adjacent to an expanding Scottish village, and model the probability of finding droppings in relation to period plus two disturbance gradients – distance to a much disturbed ‘entry zone' with a high density of tracks lying adjacent to the village, plus distance to the nearest track. Throughout the study, no droppings were found within the entry zone and their density was depressed up to 400 m from it. Density of droppings was also depressed within 100–120 m of tracks but, compared to a notional scenario without tracks, was threefold greater on ground 120–250 m from tracks. Although the number of cocks counted at the lek in spring showed a small increase, there was an almost threefold decline in the probability of finding capercaillie droppings on and within about 40 m of tracks. We infer that, after the development, birds were less likely to use or cross tracks in pursuit of their daily living requirements, with unknown consequences for their population dynamics and vital rates. Our results have implications for refuge design. Birds on roughly half of a 50 ha refuge should be undisturbed by direct effects of track‐based activities. However, birds shifting away from tracks may themselves cause local increases in density and associated, indirect disturbance such that a refuge would need to be over 300 ha to keep half of it undisturbed.

ИССЛЕДОВАНИЕ МИКРОРАСПРЕДЕЛЕНИЯ PU-239 В ПЕЧЕНИ РАБОТНИКОВ ПО «МАЯК» С ИСПОЛЬЗОВАНИЕМ НЕЙТРОННО-ИНДУЦИРОВАННОГО МЕТОДА ИЗМЕРЕНИЯ

Purpose: Conducted research was aimed at studying of microdistribution of 239Pu particles in liver tissues of former MAYAK PA workers. Current research is a continuation of studies of microdistribution of 239Pu particles in lung tissues of former MAYAK PA workers that were conducted earlier and published. Material and methods: Neutron-induced track method was utilized for studying the distribution of sizes of 239Pu nanoparticles. At Southern Urals Biophysics Institute this method was improved, optimized and adapted for studying of plutonium microdistribution in biological tissues. Liver samples studying started in 2020. Samples were chosen from Radiobiology Human Tissue Repository SUBI. Liver samples from Voronezh regional pathology and anatomical bureau and Tobolsk regional hospital #3 were obtained within the search of contemporary liver tissues. Application of liver samples on track detectors and their assembling into plastic box for following irradiation in nuclear reactor at Joint stock company “Institute of Nuclear Materials” was provided similarly to lung samples. Standart pathohistological techniqes were applied. The thickness of liver slides was 5 micrometers. Basic track count was conducted on the results of 36-minute etching. Single tracks and stars were counted. Stars with high density of tracks that exceeded counting abilities were counted on the results of 9-minute etching either directly (if all tracks were distinct) or in accordance with patent for invention RU 2733491 C2 that enables to calculate the number of tracks in a star by distinct peripheral tracks. Results: This study quantitatively compares 239Pu microdistribution in liver of three deceased former Mayak PA workers who were exposed to 239Pu by inhalation and three deceased subjects who had been never employed at Mayak PA (from Ozyorsk, Voronezh, Tobolsk). The comparison is made utilizing neutron-activation method of measurement. The results are compared to the results of less-sensitive autoradiographic method. The study demonstrated that the most of 239Pu activity in liver is concentrated in liver lobules. 239PuO2 nanoparticles found didn’t exceed the size of 20 nm. Track density for three liver samples of subjects who had been never employed at Mayak PA differed for less than two times.

Understand High Track Density in Heat Assisted Magnetic Recording

Understand High Track Density in Heat Assisted Magnetic Recording

Alpha particle spectrometry in fluorescent nuclear track detectors with an automatic 3D track reanalysis algorithm

The main obstacle to applying aluminum oxide doped with carbon and magnesium (Al2O3:C,Mg)-based fluorescent nuclear track detectors (FNTDs) in radionuclide therapy with alpha emitters is that it has not been known how to achieve an accurate and in situ dose assessment for in vitro cellular experiments. In this study, we developed an automatic 3D track reanalysis algorithm (ATRA) to analyze the alpha energy spectra in FNTDs. The algorithm provides an excellent track identification rate and an excellent track linking rate (0.961) without significant variations in various track densities. The algorithm also achieves a reliable track detection rate exceeding 0.927 for track densities at the level of in situ measurement, and it successfully measures the alpha energy spectra for obtaining the absorbed dose. We also confirmed that the track overlap clearly interferes with accurate track reconstruction for track densities beyond 1.5 × 106 tracks cm−2. We provided a correction equation that can be used to obtain the actual alpha tracks for high track densities; the equation may also correct estimations of absorbed doses due to alpha particles.

Comparative study on traditional and new etchants for radon monitoring using Poly(allyl diglycol carbonate) (PADC) and identification of (Na3H(CO3)2.2H2O) in etched products

A comparative study is conducted on Traditional Etchants (NaOH/H2O, KOH/H2O) and New Etchants viz. NaOH/Methanol, NaOH/Ethanol and NaOH/1-propanol for Poly(allyl diglycol carbonate) (PADC) used in Radon monitoring. Molar concentration of traditional etchants NaOH/H2O and KOH/H2O is varied from 1 M to 6 M and etching temperature is varied from 30 °C to 80 °C to verify optimal etching parameter. Etching is done for 8 to 9.5 h in the steps of 30 min. An average bulk etch rate (Vb) of 1.4μm/h and 1.7μm/h for NaOH/H2O and KOH/H2O is calculated respectively under optimal etching conditions. Optimal reported concentrations of 1.5 M, 1.5 M and 1 M respectively, are used to make standard NaOH/Methanol, NaOH/Ethanol and NaOH/1-propanol solutions. Track densities, track diameters, bulk etch rate (Vb), track etch rate (Vt), etching time, variation in mass and thickness for both traditional and new etchants are calculated and compared. Traditional etchants take much longer time (5 to 7 h) for etching with initial swelling due to absorption of etchant on the surface of detector due to broken molecular chains, causing increase in mass and thickness of detectors for initial 0.5 to 1 h of etching which are measured with digital balance (±0.0001 g) and digital micrometer (±0.001 mm) respectively. New etchants take short time for etching (30 min approx.). There is no initial increase in mass and thickness of detectors due to short etching time and high Vb of new etchant. Traditional etchants give high track densities with low Vb and Vt while new etchants gives low track density with high Vb and Vt. New tracks formation is rare in new etchants as compared to traditional etchants. An average radon concentration level of 21.8 kBqm−3 is calculated from detectors etched in traditional etchants while new etchants do not provide any useful information about radon track density to calculate radon concentration for the given samples. Trona i-e Na3H(CO3)2.2H2O is identified as a common product formed in the etched products of PADC etched in either of the etchants i.e. traditional etchants and new etchants, using X-ray powder diffraction (XRPD) analysis.

Investigation of neutron imaging applications using fine-grained nuclear emulsion

Neutron imaging is a nondestructive inspection technique that has a wide range of applications. One of the important aspects of neutron imaging is achieving a micrometer-scale spatial resolution. The development of a high-resolution neutron detector is a challenging task. As one potential solution to this task, we investigate whether neutron detectors based on fine-grained nuclear emulsions are suitable for high-resolution neutron imaging applications. High track density is necessary to improve the quality of neutron imaging. However, the available track analysis methods are difficult to apply under high track density conditions. Simulated images are used to determine the required track density for neutron imaging. A track density of the order of 104 tracks per 100×100μm2 is sufficient to utilize neutron detectors for imaging applications. Contrast resolution was also investigated for image datasets with various track densities and neutron transmission rates. Moreover, experiments were performed for the neutron imaging of gadolinium-based gratings with known geometries. The grating structures were successfully resolved. The calculated 1σ 10%–90% edge response using the grayscale optical images of the grating slit with a periodic structure of 9 μm was 0.945±0.004 μm.

Can the long-term effects of beach cleaning heavy duty machinery on aeolian sedimentary dynamics be detected by monitoring of vehicle tracks? An applied and methodological approach

Beach-dune systems are fragile ecosystems vulnerable to changes, especially those associated to human activities. This study focuses on El Inglés beach (Canary Islands, Spain), which is located on the eastern limit of the Maspalomas dunefield. This is the sediment input to the dunefield, and vehicles that provide urban-touristic services circulate every day, most notably heavy duty machinery responsible for beach cleaning. The aim of this study is to make a first methodological approach and a quantitative and empirical analysis of the long-term environmental effects, especially on the topography and geomorphology, that mechanical beach cleaning services could have on the aeolian dynamics, using as an indicator the vehicles tracks mapping.The methodology is divided into four sections: i) a spatiotemporal study of vehicle tracks on the beach; ii) a field campaign to observe beach cleaning activities in situ and compile data; iii) an interview with the local team responsible for beach cleaning; and iv) a general analysis of the aeolian dynamics over the almost last two decades.Results shown not only a high correlation between vehicle tracks and heavy duty machinery tracks, but also the variation in vehicle track density was proven to follow changes in the management process and the number of tourists. Different track densities varied depending on the intensity of the presence of visitors and hence the intensity of beach use, which is not homogeneous throughout the beach. A study of the deflation surfaces as erosion process found that they not only remain steady but even increase in some areas with high vehicle track densities, with no sedimentary gain. Although management activities like cleaning and levelling may not have a direct impact on the dunefield, they were positively correlated to deflation surfaces, increasing sediment loss in the beach area. These activities could be leading an artificially-maintained steady beach contrary to documented sedimentary loss in the dunefield. In conclusion, the pioneer approach of analysing the vehicle traffic through tracks monitoring, especially beach cleaning activities, has shown the viability to detect long-term effects on the sedimentary dynamics, including sediment loss to the foredune and, therefore, inside the system.

High time resolution, two-dimensional position sensitive MSMGRPC for high energy physics experiments

Two Multi-Strip Multi-Gap Resistive Plate Counters (MSMGRPCs) designed to cope with the high counting rates and track densities of the most challenging zone of the CBM-TOF wall were successfully tested in-beam in the mCBM experimental setup installed at SIS18/GSI Darmstadt facility (FAIR Phase-0). At low counting rate a 96% efficiency plateau and 45 ps time resolution were obtained. The high counting rate test showed ∼50 ps time resolution and an efficiency ≥90% at the maximum delivered counting rate of 30 kHz/cm2. For the mitigation of the gas pollution aging effects, a new detector architecture with a direct gas flow through the gas gaps is proposed. The assembled prototype was tested in-beam in the mCBM setup, obtaining similar performances with the ones obtained for the prototypes with gas exchange via diffusion.

Study on the reusability of fluorescent nuclear track detectors using optical bleaching

Fluorescent nuclear track detectors (FNTDs) based on Al2O3:C,Mg crystals are luminescent detectors that can be used for dosimetry and detection of charged particles and neutrons. These detectors can be utilized for imaging applications where a reasonably high track density, approximately of the order of 1×104 tracks in an area of 100 × 100 μm2, is required. To investigate the reusability of FNTDs for imaging applications, we present an approach to perform optical bleaching under the required track density conditions. The reusability was assessed through seven irradiation-bleaching cycles. For the irradiation, the studied FNTD was exposed to alpha-particles from an 241Am radioactive source. The optical bleaching was performed by means of ultraviolet laser light with a wavelength of 355 nm. Three dedicated regions on a single FNTD with different accumulated track densities and bleaching conditions were investigated. After every irradiation-bleaching cycle, signal-to-noise ratio was calculated to evaluate FNTD performance. It is concluded that FNTDs can be reused at least seven times for applications where accumulation of a high track density is required.

Track density imaging using diffusion tensor imaging data from 1.5 T MRI scanner

Superresolution track density imaging (TDI) has recently been developed for achieving high resolution track density maps from low-resolution diffusion images acquired at 3 T. But, the utility of the approach is still unclear when applied to diffusion tensor imaging (DTI) data acquired at lower 1.5 T magnetic field strength and thus its advantages or disadvantages awaits for exploration. We implemented an algorithm to generate track density maps of human white matter using streamline tracking and tested its performance with data acquired from two healthy volunteers at 1.5 Tesla. The effects of number of diffusion directions and seed selections on the quality of the reconstructed TDI maps were investigated under a variety of settings. The results were visually evaluated by an anatomist and a radiologist, and statistically characterized using gray level cooccurance Matrices (GLCM). Producing high-quality maps with improved resolution required increasing the number of seeds per voxel. Statistical implications were consistent with visual inspection. Low signal-to-noise ratio in DTI data intrinsically yielded low SNR in the final TD map. Accurately defining the diffusion and thus fiber orientation within a voxel necessitated increasing the number of diffusion encoding directions. Our data suggests that TDI image with DTI data acquired at 1.5 T is possible using right trade-offs in data acquisition and processing and has the capability of delineating the substructures of the brain.

Track Reconstruction in a High-Density Environment with ALICE

ALICE is the dedicated heavy-ion experiment at the CERN Large Hadron Collider (LHC). Its main tracking and particle-identification detector is a large volume Time Projection Chamber (TPC). The TPC has been designed to perform well in the high-track density environment created in high-energy heavy-ion collisions. In this proceeding, we describe the track reconstruction procedure in ALICE. In particular, we focus on the two main challenges that were faced during the Run 2 data-taking period (2015–2018) of the LHC, which were the baseline fluctuations and the local space charge distortions in the TPC. We present the corresponding solutions in detail and describe the software tools that allowed us to circumvent these challenges.

Cost-effectiveness of volunteer and contract ground-based shooting of sambar deer in Australia

Context Introduced sambar deer (Cervus unicolor) are increasing in south-eastern Australia, and both volunteer and contract ground-based shooters are being used by management agencies to control their undesirable impacts. However, little is known about the effectiveness and costs of volunteer and contract shooters for controlling deer populations in Australia. Aims We evaluated the effectiveness and costs of volunteer and contract ground-based shooters for controlling sambar deer and their impacts in a 5-year management program conducted in and around alpine peatlands in Alpine National Park, Victoria. Methods Ground-based shooting operations were organised in two blocks. Within each block, four ~4200-ha management units were delimited, of which two were randomly assigned as treatment (ground-based shooting) and two as non-treatment (no organised ground-based shooting). In the treatment units, ground-based shooting was conducted using either volunteers or contractors. Each shooting team recorded their effort and the numbers of deer seen and shot, and used a GPS to record their track log and the time and locations of deer shot. Key costs were recorded for both shooter types. Key results The catch per unit effort of contract shooters was four times greater than that of volunteer shooters. Both shooter types were most effective during the first half of the night and prior to sunrise, and when using a vehicle with a spotlight or walking with thermal-vision equipment. During the day, the use of gundogs to indicate deer significantly increased the success rate of volunteer shooters. Both volunteer and contract shooters used roads and tracks to move in the landscape, but contractors covered more ground than did volunteers. After accounting for key operational costs, the cost per deer killed was 10.1% higher for contract than volunteer shooters. Conclusions The effectiveness of ground-based shooters is increased by operating at night using vehicles, spotlights and thermal-vision equipment. Contract shooters kill sambar deer at a faster rate, but are slightly more expensive per deer killed, than are volunteer shooters. Implications Ground-based shooting is likely to be most effective when conducted at night with thermal-vision equipment, and in areas with a high density of roads and tracks.

Monthly prediction of tropical cyclone activity over the South China Sea using the FGOALS-f2 ensemble prediction system

The monthly prediction skill for tropical cyclone (TC) activity in the South China Sea (SCS) during the typhoon season (July to November) was evaluated using the FGOALS-f2 ensemble prediction system. Specifically, the prediction skill of the system at a 10-day lead time for monthly TC activity is given based on 35-year (1981–2015) hindcasts with 24 ensemble members. The results show that FGOALS-f2 can capture the climatology of TC track densities in each month, but there is a delay in the monthly southward movement in the area of high track densities of TCs. The temporal correlation coefficient of TC frequency fluctuates across the different months, among which the highest appears in October (0.59) and the lowest in August (0.30). The rank correlation coefficients of TC track densities are relatively higher (R > 0.6) in July, September, and November, while those in August and October are relatively lower (R within 0.2 to 0.6). For real-time prediction of TCs in 2020 (July to November), FGOALS-f2 demonstrates a skillful probabilistic prediction of TC genesis and movement. Besides, the system successfully forecasts the correct sign of monthly anomalies of TC frequency and accumulated cyclone energy for 2020 (July to November) in the SCS.摘要本研究基于新一代FGOALS-f2动力集合预测系统35年 (1981–2015年) 的热带气旋历史回报试验对南海台风季 (7–11月) 热带气旋活动超前10天的月预测技巧进行评估, 并对2020年南海台风季热带气旋活动进行了实时月预测尝试. 结果表明: FGOALS-f2能较好地预测南海热带气旋路径密度演变特征, 预测的热带气旋生成个数与实际观测结果的相关系数在0.2–0.6之间. 2020年实时预测方面, FGOALS-f2较为准确地给出了南海台风季热带气旋生成位置与移动路径的概率预测, 且对南海热带气旋生成个数和强度异常的确定性预测结果与观测接近.

Intrinsic time resolution of 3D-trench silicon pixels for charged particle detection

In the last years, high-resolution time tagging has emerged as a promising tool to tackle the problem of high-track density in the detectors of the next generation of experiments at particle colliders. Time resolutions below 50 ps and event average repetition rates of tens of MHz on sensor pixels having a pitch of 50 μm are typical minimum requirements. This poses an important scientific and technological challenge on the development of particle sensors and processing electronics. The TIMESPOT initiative (which stands for TIME and SPace real-time Operating Tracker) aims at the development of a full prototype detection system suitable for the particle trackers of the next-to-come particle physics experiments. This paper describes the results obtained on the first batch of TIMESPOT silicon sensors, based on a novel 3D MEMS (micro electro-mechanical systems) design. We demonstrate that following this approach, the performance of other ongoing silicon sensor developments can be matched and overcome. In addition, 3D technology has already been proved to be robust against radiation damage. A time resolution of the order of 20 ps has been measured at room temperature suggesting also possible improvements after further optimisations of the front-end electronics processing stage.

Super-resolution microscopy reveals majorly mono- and dimeric presenilin1/γ-secretase at the cell surface.

γ-Secretase is a multi-subunit enzyme whose aberrant activity is associated with Alzheimer's disease and cancer. While its structure is atomically resolved, γ-secretase localization in the membrane in situ relies mostly on biochemical data. Here, we combined fluorescent tagging of γ-secretase subunits with super-resolution microscopy in fibroblasts. Structured illumination microscopy revealed single γ-secretase complexes with a monodisperse distribution and in a 1:1 stoichiometry of PSEN1 and nicastrin subunits. In living cells, sptPALM revealed PSEN1/γ-secretase mainly with directed motility and frequenting 'hotspots' or high track-density areas that are sensitive to γ-secretase inhibitors. We visualized γ-secretase association with substrates like amyloid precursor protein and N-cadherin, but not with its sheddases ADAM10 or BACE1 at the cell surface, arguing against pre-formed megadalton complexes. Nonetheless, in living cells PSEN1/γ-secretase transiently visits ADAM10 hotspots. Our results highlight the power of super-resolution microscopy for the study of γ-secretase distribution and dynamics in the membrane.

High performance timing detectors for high energy physics experiments and new developments for the high luminosity LHC

In recent years precision timing detectors have increasingly captured the interest of the particle physicists, for their potential as time of flight detectors in high luminosity collider experiments as the LHC. In Phase-1 of the LHC, the experiments have exploited a global event description, making use of all subdetector information (tracks, calorimeter hits and muon chamber hits) to optimize the particle energy and position measurement depending on the particle type. This technique usually referred to as “particle flow” has a beneficial effect particularly on the jet energy and on the missing transverse energy resolution. In 2025 a new phase of the Large Hadron Collider will begin with increased instantaneous luminosity (HL-LHC) and a number of concurrent proton-proton interactions per bunch crossing as high as 200. Therefore the events will have very high vertex and track density, and high hit occupancy will be detected in the calorimeters. Hence the need to exploit additional measurement, like the timing information, for the track to vertex matching algorithms and for the association of calorimeter hits to tracks, in order to be able to efficiently use the particle flow technique in these harsher conditions. This lecture reviews the existing detectors with fast and precise timing measurement as well as the physics motivation for their use. It will introduce the various detector technologies able to achieve high performance in timing: Micro-channel plates, scintillation crystals coupled to high gain photodetectors, and silicon based detectors as Low Gain Avalanche devices.

Simultaneous characterization of cross- and in-plane thermal transport in insulator patterned by directionally aligned nano-channels

Anisotropic thermal transport behavior was investigated in a single crystal sapphire patterned by vertically aligned few-nanometer diameter and several micrometer long cylindrical ion tracks. These ion tracks were introduced by exposing the sapphire to energetic ions of xenon accelerated to 167 MeV with fluences ranging from 1012 to 1014 ions/cm2. It was found that, in the low ion-track density regime, cross-plane thermal conductivity is larger, whereas in the high track density regime, the trend reverses and in-plane conductivity becomes larger. The crossover between these regimes is attributed to the interplay between phonon scattering with ion track boundaries and phonon confinement effects. In the low track density regime, the material is described by bulk phonon dispersion and anisotropy in thermal transport is attributed to the aligned nature of tracks that effectively reduce the mean free path of phonons traveling in the in-plane direction more than in the cross-plane direction. In the high-density regime, larger conductivity reduction in the cross-plane direction is consistent with previous observations, where the anisotropic reduction in thermal conductivity is owed to the anisotropic reduction of acoustic velocity caused by phonon confinement. Our results are further supported by an analytical model describing phonon mediated thermal transport.

A Study on Block-Based Neural Network Equalization in TDMR System With LDPC Coding

To achieve a high track density, two-dimensional magnetic recording (TDMR) is combined with shingled magnetic recording (SMR). SMR makes it possible to record 1 bit on a few grains. However, the performance will be remarkably deteriorated by the increased media noise, the inter-track and inter-symbol interference (ITI and ISI). Therefore, the application of effective equalization and error control coding are required. In this paper, we investigate a simple block-based neural network equalizer (NNE) that mitigates the influence of ITI and ISI. We compare the equalization effects of the NNE and a conventional 2-D equalizer with low-density parity-check (LDPC) coding based on a random Voronoi grain media model. Simulation results show the proposed block-based NNE achieves better bit error rate performance than the conventional 2-D linear equalizer followed by the a posteriori probability (APP) detector and a sum-product (SP) decoder. In addition, we find the block-based NNE is sensitive to write errors.

Adjacent Track Interference in Heat-Assisted Magnetic Recording: Impact and Implications

Some aspects of the challenges to high track density heat-assisted magnetic recording (HAMR) are addressed with a focus on track interferences (adjacent as well as non-nearest neighbor erasure). Comparisons with corresponding conventional perpendicular magnetic recording (PMR) parameters are also made. Adjacent and non-nearest neighbor track erasure data from functional HAMR and PMR drives and simulation data of signal-to-noise ratio loss in HAMR are also presented.

Effects of ECE duration on alpha particle tracks in polycarbonate nuclear track detectors over broad ranges of fluence and energy

The effects of electrochemical etching (ECE) duration on alpha particle detection efficiency in polycarbonate nuclear track detectors over broad ranges of fluence and energy were studied in this paper. This is of particular importance when efficient detection of charged particle tracks with densities > 106 tracks/cm2 in particular in plasma focus devices is of concern. However, at high track densities, tracks overlap and make track density and diameter determination especially at low alpha particle energies rather difficult and inaccurate, if not impossible. Accordingly, track density and mean track diameter to obtain alpha particle detection efficiency were studied in 500 μm thick detectors exposed to alpha particle fluences up to ∼1.0 × 107 alphas/cm2 at defined alpha energies from ∼0.3 to ∼3.0 MeV for ECE durations from 0.5 to 6.0 hours. Microphotographs of alpha particles at different conditions applied are also reported in order to assist researchers in better understanding the morphology of tracks in order to apply optimum conditions for specific applications of concern.