Shape Discrimination Research Articles

Measurements of AmBe and PuC spectra using EJ309 and stilbene scintillators

Two organic scintillators (EJ309 and stilbene) with their different detection chains and elaborate software were used to measure neutron spectra of AmBe and PuC sources. Method of shadow cone ensures minimization of scattered neutron influence. To separate neutrons and γ, a modern method of pulse shape discrimination was employed using fast digitizers. Calibration was performed by γ sources and three different methods for the identification of the Compton edge. Spectrometric systems also used different light output functions and unfolding methods. The same spectra were calculated using the MCNP6 code and the JENDL-5 library. The measured and calculated results were mutually compared, and also with the published results available in the literature. Generally, the results agree on the main peaks of neutron spectra but differ in their abundance. The lower limit for the ability to distinguish between neutrons and γ in spectrometry with organic scintillators was found at about 1.5 MeV.

Pulse shape discrimination for the CONUS experiment in the keV and sub-keV regime

Point-contact p-type high-purity germanium detectors (PPC HPGe) are particularly suited for detection of sub-keV nuclear recoils from coherent elastic scattering of neutrinos or light dark matter particles. While these particles are expected to interact homogeneously in the entire detector volume, specific classes of external background radiation preferably deposit their energy close to the semi-active detector surface, in which diffusion processes dominate that subsequently lead to slower rising pulses compared to the ones from the fully active bulk volume. Dedicated studies of their shape are therefore highly beneficial for the understanding and the rejection of these unwanted events. This article reports about the development of a data-driven pulse shape discrimination (PSD) method for the four 1 kg size PPC HPGe detectors of the Conus experiment in the keV and sub-keV regime down to 210 eVee.\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{ee}.$$\\end{document} The impact of the electronic noise at such low energies is carefully examined. It is shown that for an acceptance of 90% of the faster signal-like pulses from the bulk volume, approx. 50% of the surface events can be rejected at the energy threshold and that their contribution is fully suppressed above 800 eVee.\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{ee}.$$\\end{document} Applied to the Conus background data, such a PSD rejection cut allows to achieve an overall (15-25)%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(15{-}25)\\%$$\\end{document} reduction of the total background budget. The new method allows to improve the sensitivity of future Conus analyses and to refine the corresponding background model in the sub-keV energy region.

Racial/Ethnic Disparities in Renters’ Experiences with Maintenance Delays in the United States

Structural racism and individual discrimination contribute to racial inequalities in poor housing conditions in the United States. Less is known about whether and how structural racism and individual discrimination shape a parallel, but distinct, process that is also consequential for family wellbeing: experiencing housing unit maintenance delays. Maintenance delays transform acute problems into chronic stressors and increase exposure to physical hazards over time. Using the 2013 American Housing Survey, I examine racial/ethnic disparities in maintenance delays across non-Hispanic White, Black, Hispanic, Asian, and American Indian/Alaska Native renters. Given that 2.3 million low-income households rent using Housing Choice Vouchers (HCVs), a federal housing assistance program with requirements around repair timing, I also examine how renting with a voucher shapes maintenance delays. There are three principal findings. First, White renters are more likely to report timely repairs than either Black or Hispanic renters. Second, for Black renters, both structural racism experienced in rental markets and individual discrimination drive this disparity, whereas Hispanic renters’ diverging maintenance experiences are largely explained by pathways impacted by structural racism. Third, renting with an HCV is not associated with repair timeliness for any racial/ethnic group. Taken together, the findings suggest that racial/ethnic disparities in substandard housing emerge not only through unequal exposure to housing quality problems but also through unequal responses to these issues.

Pulse shape discrimination at the registration of 14.6 MeV neutrons with Gd3Al2Ga3O12:Ce/SiPM(PMT) detectors

Gd3Al2Ga3O12:Ce (GAGG) scintillators with different readout photo-sensors, a 2 × 2 matrix of four SensL ARRAY J-60035-4P-BGA silicon photomultipliers (SiPMs), and a HAMAMATSU R5505-70 photomultiplier (PMT) have been tested for neutrons obtained from neutron generators exploiting d-d and d-t reactions. It was demonstrated that neutrons having energy 2.8 MeV produce in the detector materials the spectrum of secondary particles, which is identical to the spectrum measured under thermal neutrons of the isotope sources. The pulse height spectra detected under 14.6 MeV neutrons were found to be quite different. Pulse shape discrimination (PSD) data processing technique was applied to separate neutron and γ-ray signals. The signals of secondary particles, protons, and α-particles were confidently distinguished at the strong background of the γ-rays. The results gathered open up the prospects of using the GAGG scintillator to identify neutrons generated in d-t reactions against a strong background of γ-rays.

MS3Net: a deep ensemble learning approach for ship classification in heterogeneous remote sensing data

ABSTRACT Maritime ship classification is essential for effectively monitoring oceanic activities but faces challenges when using heterogeneous remote sensing data. This research presents a novel dataset called Heterogeneous Ship Data, created by combining synthetic aperture radar (SAR) and optical satellite images of ships. The integration of multimodal data aims to harness the complementary advantages of SAR’s all-weather imaging capabilities and optical data’s higher interretability and shape discrimination. To leverage the heterogeneous dataset, this paper proposes an ensemble deep learning model called MS3Net (Multi-convolutional network using Spatial attention and Second-order pooling for Ship image classification). MS3Net integrates spatial attention mechanisms and second-order pooling. MS3Net has multiple convolutional branches, each tailored to extract distinct representations from the SAR and optical data through varied filter sizes and kernels. The spatial attention units focus the learning on the most informative parts of the image while suppressing irrelevant features. The second-order pooling captures higher-order interactions between feature elements to model complex relationships. A concatenation fusion strategy aggregates the diverse branch outputs into a joint multimodal feature representation for enhanced discrimination. Extensive experiments demonstrate MS3Net’s superior classification accuracy over prior state-of-the-art approaches. The proposed heterogeneous data representation coupled with the attention-based deep ensemble learning model contributes to maritime surveillance by enabling robust ship recognition across diverse sensing modalities.

Neutron-gamma pulse shape discrimination for EJ301 liquid scintillator based on machine learning

Neutron-gamma pulse shape discrimination for EJ301 liquid scintillator based on machine learning

The Preparatory Activation of Guidance Templates for Visual Search and of Target Templates in Non-Search Tasks.

Representations of task-relevant object attributes (attentional templates) control the adaptive selectivity of visual processing. Previous studies have demonstrated that templates involved in the guidance of attention during visual search are activated in a preparatory fashion prior to the arrival of visual search displays. The current study investigated whether such proactive mechanisms are also triggered in non-search tasks, where attentional templates do not mediate the guidance of attention towards targets amongst distractors but are still necessary for subsequent target recognition processes. Participants either searched for colour-defined targets among multiple distractors or performed two other non-search tasks where imperative stimuli appeared without competing distractors (a colour-based Go/NoGo task, and a shape discrimination task where target colour was constant and could thus be ignored). Preparatory activation of colour-selective templates was tracked by measuring N2pc components (markers of attention allocation) to task-irrelevant colour singleton probes flashed every 200 ms during the interval between target displays. As expected, N2pcs were triggered by target-coloured probes in the search task, indicating that a corresponding guidance template was triggered proactively. Critically, clear probe N2pcs were also observed in the Go/NoGo task, and even in the shape discrimination task in an attenuated fashion. These findings demonstrate that the preparatory activation of feature-selective attentional task settings is not uniquely associated with the guidance of visual search but is also present in other types of visual selection tasks where guidance is not required.

Neutron-gamma discrimination with broaden the lower limit of energy threshold using BP neural network

Neutron-gamma discrimination is a tough and significative in experimental neutrons measurements procedure, especially for low-energy neutrons signal discrimination. In this work, based on the Pulse Shape Discrimination (PSD) and Back-Propagation (BP) artificial neural networks, a neutron-gamma discrimination method is developed to broaden the lower limit of energy threshold with the hidden layer of 20 neurons. Compared with neutron-gamma discrimination method based on PSD only, the developed neutron-gamma discrimination method based on the PSD and BP-ANN can discriminate neutron and gamma-ray signals with low energy threshold, which can discriminate signals up to 99.93%. Moreover, this work can reduce the energy threshold from 350 keV to 70 keV, as well as the acquired data utilization increased from 60% to more than 99.9%, which overcome the hardware limitations and distinguish neutron and gamma-ray signals, effectively. The developed neutron-gamma discrimination method and the trained neural network can be directly used to other experimental neutrons measurements.

The Neutron-Gamma Pulse Shape Discrimination of CLLB Detector

The Neutron-Gamma Pulse Shape Discrimination of CLLB Detector

Scintillation properties of lithium-6 salicylate-loaded liquid scintillators.

The limited availability of conventional 3He proportional counters provides impetus for developing novel neutron detectors. As a candidate, lithium-6-loaded liquid scintillators with neutron/gamma pulse shape discrimination (n-γ PSD) capabilities have been developed. However, the trade-off relationship between the 6Li-loading amount and scintillation light yield is a significant problem. This is because 6Li-loading involves the addition of non-luminescent materials, which cause non-radiative relaxation of the excited states. Therefore, aiming to reduce non-radiative relaxation, we chose lithium-6 salicylate (6LiSal), which shows fluorescence in the visible light region, as a chemical for 6Li-loading. In this study, we analyzed the photoluminescence/scintillation properties based on the Förster resonance energy transfer and investigated the optimal content for obtaining a high light yield. By maximizing the sequential energy transfer from the solvent (toluene) to the phosphor (POPOP), a high light yield 6Li-loaded liquid scintillator (4220 photons per MeV under gamma-ray irradiation) with a 6Li concentration of approximately 0.1 wt% was developed. Thermal neutron events were successfully detected with a light yield of 3970 photons per neutron, which is more than three times higher than those of other organic scintillators. In addition, focusing on the triplet-triplet annihilation process and further optimizing the component for the n-γ PSD, the thermal neutron and gamma-ray events were successfully separated. The developed high light yield 6Li-loaded liquid scintillators show n-γ PSD capabilities and can be promising candidates as alternative detectors to the 3He proportional counter.

Characterization of organic glass scintillator bars and their potential for a hybrid neutron/gamma ray imaging system for proton radiotherapy range verification

For accurate and simultaneous imaging of fast neutrons (FNs) and prompt gamma rays (PGs) produced during proton therapy, the selection of a highly performant detector material is crucial. In this work, a promising candidate material known as organic glass scintillator (OGS) is characterized for this task. To this end, a precisely-timed source of neutrons and Bremsstrahlung radiation produced by the nELBE facility was used to study the light output and neutron/gamma ray pulse shape discrimination (PSD) properties of a 1 × 1 × 20 cm3 OGS bar with double-sided readout. Furthermore, the energy, timing, and depth-of-interaction (DOI) resolutions of 1 × 1 × 10 cm3 and 1 × 1 × 20 cm3 OGS and EJ-200 bars were characterized with radioactive sources. For electron-equivalent energies above 0.5 MeVee, OGS was found to have excellent PSD capabilities (figure-of-merit above 1.27), energy resolution (below 12%), coincident time resolution (below 500 ps), and DOI resolution (below 10 mm). This work establishes the data analysis methods required for hybrid FN/PG imaging using OGS, and demonstrates the materials' excellent performance for this application.

The influence of oxygen on pulse shape discrimination at various solvents and phosphors

The influence of oxygen on pulse shape discrimination at various solvents and phosphors

Changes in the dopaminergic circuitry and adult neurogenesis linked to reinforcement learning in corvids.

The caudolateral nidopallium (NCL, an analog of the prefrontal cortex) is known to be involved in learning, memory, and discrimination in corvids (a songbird), whereas the involvement of other brain regions in these phenomena is not well explored. We used house crows (Corvus splendens) to explore the neural correlates of learning and decision-making by initially training them on a shape discrimination task followed by immunohistochemistry to study the immediate early gene expression (Arc), a dopaminoceptive neuronal marker (DARPP-32, Dopamine- and cAMP-regulated phosphoprotein, Mr 32 kDa) to understand the involvement of the reward pathway and an immature neuronal marker (DCX, doublecortin) to detect learning-induced changes in adult neurogenesis. We performed neuronal counts and neuronal tracing, followed by morphometric analyses. Our present results have demonstrated that besides NCL, other parts of the caudal nidopallium (NC), avian basal ganglia, and intriguingly, vocal control regions in house crows are involved in visual discrimination. We have also found that training on the visual discrimination task can be correlated with neurite pruning in mature dopaminoceptive neurons and immature DCX-positive neurons in the NC of house crows. Furthermore, there is an increase in the incorporation of new neurons throughout NC and the medial striatum which can also be linked to learning. For the first time, our results demonstrate that a combination of structural changes in mature and immature neurons and adult neurogenesis are linked to learning in corvids.

Linking Labour Market Aspirations to Perceived Discrimination: The Case of Refugees in Norway

This article provides a close look at the possible connection between labour market aspirations and perceptions of discrimination. While research on policy implementation and public measures are plentiful regarding immigrants’ labour market integration, less attention has been given to what shapes immigrants’ motivation and desires to become part of the labour market. Following the idea that migrants’ capacity to exert agency is shaped by given — or perceived — opportunity structures the author examines how discrimination, as a specific structural constraint, influence their capacity to aspire in the labour market. This article draws on ethnographic fieldwork among refugees settling in Norway. The findings indicate discrimination as a salient part of their migration experiences. Based on how they negotiate and resist discrimination, the author coins the terms “aspirational deprivation” and “aspirational deskilling” to capture how the refugees’ responses to perceived discrimination shape labour market aspirations.

Intraspecific Shape Analysis of Bali Sardinella (Sardinella lemuru) Using Geometric Morphometrics Collected in the Coast of Cabadbaran, Agusan Del Norte, Philippines

Modern techniques are often applied to analyze the body shape differences among biological organisms. Also, taxonomy and systematics are two essential fields of Biology concerning shape discrimination. This study aims to identify the shape variations of Sardinella lemuru (Bali sardinella) using Symmetry Asymmetry Geometric Data (SAGE) Software Application. A total of 70 fish samples consisting of 35 males and 35 females were collected in Barangay Caasinan, Cabadbaran, Agusan Del Norte, Philippines. Standard laboratory procedures were done and fish samples were subjected to the analysis. Procrustes ANOVA revealed a highly significant difference (P<0.0001) among the components analyzed (individuals, sides, and individuals vs. sides). This implied that each of the fish samples exhibited different body shapes. Principal Component Analysis (PCA) obtained a high rate of Interaction/Fluctuating Asymmetry (76.79%) in males when compared to female samples (74.08%). The shape dissimilarities within the populations were associated with genetic components, ecological adaptations-swimming, predator escape, and resource competition. Thus, the present study identified shape disparity within the fish populations. The development of employing modern techniques enhances scientific methods to quantify shape dissimilarities among species individuals and assemblages.

Comparative study of ratio and spectral shape discrimination technique in case of physics event selection for point contact germanium detector in sub-$$keV_{ee}$$ range

Comparative study of ratio and spectral shape discrimination technique in case of physics event selection for point contact germanium detector in sub-$$keV_{ee}$$ range

Novel environmental monitoring detector for discriminating fallout and airborne radioactivity

Early warning networks are used for detecting abnormal radioactivity levels in the environment. State-of-the-art networks are equipped with both dose rate detectors and spectrometric stations. Current networks don’t automatically discriminate between radioactivity on the ground and in the air. A novel directional sensing gamma radiation detector utilizing a collimated phoswich scintillator was developed. The signals from the two scintillator materials are separated using a pulse shape discrimination. The separated signals are employed to determine the radioactivity concentrations on the ground and in the air assuming specific concentration distributions. Limitations related to imperfect directional sensing and dead time are discussed.

A commentary on two NIM A papers by N. Zaitseva et al. on scintillation properties of solution-grown trans-stilbene single crystals and on recent developments in plastic scintillators with pulse shape discrimination

A commentary on two NIM A papers by N. Zaitseva et al. on scintillation properties of solution-grown trans-stilbene single crystals and on recent developments in plastic scintillators with pulse shape discrimination

A Self-Organizing feature Map neural network for compton suppression in phoswich detector

Scintillation phoswich detectors can be used for particle discrimination and Compton suppression, and their function is based on pulse shape discrimination (PSD) methods. The conventional PSD methods mainly including Rise Time Discrimination (RTD), Rise and Decay time discrimination (R&D), Constant Time Discrimination (CTD), etc., but linear PSD methods have their limitations in processing pulse signals. Neural network tools can achieve nonlinear output by adjusting the weights between neurons during the training, which are suitable for identifying nonlinear signals generated by detectors. The self-organizing feature mapping (SOM) is the most commonly used clustering neural network, which can cluster signals based on their similarity through competitive training of neural networks without prior data. In this study, 3 SOM networks with different size are trained, and after comparison with the single LaBr3:Ce detector, the total accuracy of the phoswich detector using the SOM neural network for discrimination reaches over 99.5%, which is a 7.59% increase in accuracy compared to the RTD method, and the peak-to-total ratio (P/T) is improved by 1.07%.

Experiences of Discrimination and Interest in Alzheimer’s Disease Predictive Testing in the Health and Retirement Study

AbstractBackgroundRapid developments in Alzheimer’s disease (AD) biomarker research suggest predictive testing may soon become a feasible option available to the public. Future reduction of racial and ethnic disparities in AD requires understanding of potential differences in drivers of interest in AD diagnostic testing. Experiences of discrimination may influence attitude toward AD testing, particularly among racially and ethnically minoritized populations. This study examines whether everyday or lifetime discrimination shapes interest in AD predictive testing.MethodData were collected from 1,472 participants in the 2010 and 2012 waves of the Health and Retirement Study who answered a module on interest in receiving a free test that could tell whether they would develop AD in the future, along with measures of Everyday Discrimination and Lifetime Discrimination. Logistic models were controlled for deciles of propensity scores (estimated using demographic and socioeconomic variables) and odds ratios were re‐expressed as risk differences (RD). The RD is the difference in the probability a person expressed interest in receiving a future AD predictive test based on past experiences of discrimination.ResultThe mean age of the sample was 67 (SD = 10.2), 65.9% were white, and 80% endorsed interest in AD predictive testing. Most (64.1%) participants indicated experiencing everyday discrimination in at least one domain, and 34.8% experienced major lifetime discrimination in at least one domain. Those interested in predictive testing were younger (66 vs 70 years) and more likely to be Black (20% vs 15%) or Latinx (14% vs 8%) than participants uninterested in testing. The probability of wanting an AD test was not associated with discrimination experiences for Black (RD everyday discrimination = 0.104, p = 0.285; RD lifetime discrimination = ‐0.038; p = 0.626) or Latinx (RD everyday discrimination = ‐0.003, p = 0.974; RD lifetime discrimination = ‐0.053; p = 0.692) participants.ConclusionDespite historical and contemporary experiences of discrimination, Black and Latinx individuals express interest in AD testing. This finding implicates structural and systemic barriers, such as systemic racism and institutional gaps in access to clinical research, as likely explanations for underrepresentation of racially and ethnically minoritized persons in research on AD testing.