Coincidence Method Research Articles

Observation of sequential three-body dissociation of camphor molecule—a native frame approach

Abstract The three-body dissociation dynamics of the dicationic camphor molecule (C10H16O2+) resulting from Auger decay are investigated using soft x-ray synchrotron radiation. A photoelectron-photoion-photoion coincidence method, a combination of a velocity map imaging spectrometer and a time-of-flight spectrometer is employed to measure the 3D momenta of ions detected in coincidence. The ion mass spectra and the ion–ion coincidence map at photon energies of 287.9 eV (below the C 1s ionization potential) and 292.4 eV (above the C 1s ionization potential for skeletal carbon) reveal that fragmentation depends on the final dicationic state rather than the initial excitation. Using the native frame method, three new fragmentation channels are discussed; (1) CH2CO+ + C7H 11 + + CH3, (2) CH 3 + + C7H 11 + + CH2CO, and (3) C2H 5 + + C6H 9 + + CH2CO. The dominating nature of sequential decay with deferred charge separation is clearly evidenced in all three channels. The results are discussed based on the experimental angular distributions and momenta distributions, corroborated by geometry optimization of the ground, monocationic, and dicationic camphor molecule.

On detection of BaO molecular lines in sunspot spectrum

ContextSpectral lines of diatomic molecules are perfect tools for studying the structure of sunspots and their temperature layers and magnetic sensitive absorption features, which are typically higher than in atomic lines. The integrated intensities of a few bands in the rotational structure of the astrophysically significant A1Σ+−X1Σ+and A′1Π−X1Σ+ systems of barium monoxide (BaO) have been measured experimentally using band spectra. An analysis of the prominent lines of (0, 0; 1, 1; 2, 2) bands of A1Σ+−X1Σ+transition and (0, 0; 1, 1; 2, 2) bands of A′1Π−X1Σ+transition with those of sunspot umbral spectrum. The effective rotational temperatures of the A′1Π−X1Σ+transition of BaO in the sunspot umbral spectrum are found to be in the range of 1600 K to 3200 K. AimsAn analysis of BaO prominent rotational molecular lines of A1Σ+−X1Σ+and A′1Π−X1Σ+transition with those of sunspot umbral spectral lines. To find the significant values of radiative transition parameters, vibrational temperature and the effective rotational temperature of the molecule in celestial objects. MethodsCalibrated the rotational structure of molecular band heads and lines for and A1Σ+−X1Σ+and A′1Π−X1Σ+ransitions in laboratory spectrum using most precise Hartmann's technique. High resolution FTS sunspot umbral spectra from NSO/Kitt Peak were used to detect rotational molecular lines due to the A′1Π−X1Σ+transition of the BaO molecule using the method of line coincidence. The effective rotational temperature was derived from the variation of equivalent width (W) with rotational quantum number (J) of spectrally well resolved rotational lines of a band in umbral spectrum. The triangular profile approximation method was used to estimate the equivalent width of the well resolved spectral lines. ResultsThe effective rotational temperatures of the A′1Π−X1Σ+transition of BaO in the sunspot umbral spectrum are found to be in the range of 1600 K to 3200 K. It is compared with other results with a view to obtaining useful physical parameters. This is an evidence to ascertain the possible presence of BaO molecule in solar spectrum in different layers. ConclusionsUnblended rotational lines due to the band of BaO, provide a good range of temperatures for the study of absorbing layers in umbral spectra. The A′1Π−X1Σ+transition of BaO molecular lines is found to be very sensitive to effective temperature. Radiative transition parameters data of these lines, in contrast to intensity measurements, provide us with more direct and detailed information to study the coolest parts of sunspot umbrae.

Continuous beta monitoring technology for uncontrolled radiological release in underwater using integrated beta and gamma detection system

A monitoring system capable of in-situ beta detection has been developed to address the potential risks associated with radioactive releases from nuclear sites. Although releases are controlled within permissible limits and follow strict protocols to minimize environmental and public health impacts, incidents of uncontrolled releases due to human or mechanical failures have occurred, resulting in contamination of underground water sources. To improve response capabilities, transitioning from traditional sample-based monitoring to real-time monitoring of underground water is crucial. The system utilized an NaI(Tl) detector for gamma nuclides and two plastic scintillation detectors for beta nuclides. Beta detection was facilitated through a coincidence method involving the two plastic scintillators, with any influence from gamma radiation effectively mitigated using data from the NaI(Tl) detector. This configuration ensured accurate measurement of beta radiation by removing gamma contributions from the coincidence counts. The system, which was evaluated using detection experiments for beta nuclides 3H and 90Sr, achieved a minimum detectable activity that satisfied the criteria for restricting the intake, distribution, or consumption of 90Sr and 3H to 0.1 and 100 Bq/g, respectively, within 20 min.

Study of the Neutrino–Oxygen Cross Sections of the Charged-Current Reaction 16O(ν̄e, e+)16N(0 MeV, 2–) and the Neutral-Current Reaction 16O(ν, ν′)16O(12.97/12.53 MeV, 2–), Producing High-Energy γ Rays

Abstract In our previous work, we discussed the cross section and the detection of 4.4 MeV $\gamma$ rays produced in the neutrino neutral-current (NC) reaction $^{16}$O$(\nu , \nu ^{\prime })^{16}$O(12.97 and 12.53 MeV, $2^-$) in a water Cherenkov detector at low energy below 100 MeV. In this report, we further investigate both the charged-current reaction $^{16}$O$(\bar{\nu }_e, e^+)^{16}$N(0 MeV, $2^-$) and the NC reaction$^{16}$O$(\nu , \nu ^{\prime })^{16}$O(12.97 and 12.53 MeV, $2^-$), producing high-energy $\gamma$ rays, in which a more solid identification of the reactions can be applied via the coincidence method.

The shape of the Tz = +1 nucleus 94Pd and the role of proton-neutron interactions on the structure of its excited states

Reduced transition probabilities have been extracted between excited, yrast states in the N=Z+2 nucleus 94Pd. The transitions of interest were observed following decays of the Iπ=14+, Ex=2129-keV isomeric state, which was populated following the projectile fragmentation of a 124Xe primary beam at the GSI Helmholtzzentrum für Schwerionenforschung accelerator facility as part of FAIR Phase-0. Experimental information regarding the reduced E2 transition strengths for the decays of the yrast 8+ and 6+ states was determined following isomer-delayed Eγ1−Eγ2−△T2,1 coincidence method, using the LaBr3(Ce)-based FATIMA fast-timing coincidence gamma-ray array, which allowed direct determination of lifetimes of states in 94Pd using the Generalized Centroid Difference (GCD) method. The experimental value for the half-life of the yrast 8+ state of 755(106) ps results in a reduced transition probability of B(E2:8→+6+) = 205−25+34 e2fm4, which enables a precise verification of shell-model calculations for this unique system, lying directly between the N=Z line and the N=50 neutron shell closure. The determined B(E2) value provides an insight into the purity of (g9/2)n configurations in competition with admixtures from excitations between the (lower) N=3pf and (higher) N=4gds orbitals for the first time. The results indicate weak collectivity expected for near-zero quadrupole deformation and an increasing importance of the T=0 proton-neutron interaction at N=48.

Measurement of the response of a [formula omitted]Li-glass detector to gamma rays by a coincidence method

The response of a gamma-ray spectrometer is generally determined by analyzing full-energy peaks. However, full-energy peaks cannot be measured easily in the case of scintillation detectors that consist of light elements, such as glass scintillators. Only a strong Compton plateau appears in the spectrum of such detectors. Therefore, Compton edgers were used to evaluate the response of these detectors. The response of a low-resolution 6Li-glass detector to gamma rays was measured for the first time by a coincidence method with a high-resolution LaBr3:Ce detector using cascade gamma rays (2.75 and 1.37 MeV) from a 24Na source. Coincidence gates were applied at the peaks of the spectrum of the LaBr3:Ce detector at the 0.51 MeV annihilation peak, and the sum peaks of a gamma ray and a backscattered gamma ray. By analyzing the gated spectra of the 6Li-glass detector, the energy-dependent detector response (i.e., the output strength and its dispersion) was determined.

Focal plane coincidence method for a multi-view telecentric 3D imaging system.

Multi-view microscopic fringe projection systems, which use high-resolution telecentric lenses and the Scheimpflug condition, face challenges in coinciding focal planes accurately, resulting in inconsistent measurements between views. In this Letter, we developed a sharpness evaluation function based on the total power of the line-spread function, which was subsequently used to generate a full-field sharpness distribution map. Then we employed the correlation between the sharpness map and orientation of the focal plane to precisely coincide the focal planes. Experimental results validate the proposed method and demonstrate its improved consistency in 3D reconstruction.

Development of novel positron lifetime measurement system for potential liquid material inspection

β+-γ coincidence method and anti-coincidence method have great potential in positron annihilation lifetime (PAL) measurements of liquid material. Based on anti-coincidence method with the advantage of better picking out positron annihilation events in the sample, a novel PAL spectrometer, which can isolate the sample from the positron source and is suitable for liquid material inspection, is developed. The influences of the measuring geometry and the signal processing on the anti-coincidence effect are systematically studied. By comparing the PAL spectra of well annealed pure iron acquired by the new system with that acquired by the conventional system, the performance of system is evaluated. The analysis results of PAL spectra at different distances from the sample to the source and precise measurement of PAL in liquid water show that reliable values are obtained for liquid material inspection at an adjustable distance of less than 1.0 mm. This system is expected to be applied to liquid scintillators, oils or other special materials, which could easily contaminate the positron source.

Unveiling the double-peak structure of quantum oscillations in the specific heat

Quantum oscillation phenomenon is an essential tool to understand the electronic structure of quantum matter. Here we report a systematic study of quantum oscillations in the electronic specific heat Cel in natural graphite. We show that the crossing of a single spin Landau level and the Fermi energy give rise to a double-peak structure, in striking contrast to the single peak expected from Lifshitz-Kosevich theory. Intriguingly, the double-peak structure is predicted by the kernel term for Cel/T in the free electron theory. The Cel/T represents a spectroscopic tuning fork of width 4.8kBT which can be tuned at will to resonance. Using a coincidence method, the double-peak structure can be used to accurately determine the Landé g-factors of quantum materials. More generally, the tuning fork can be used to reveal any peak in fermionic density of states tuned by magnetic field, such as Lifshitz transition in heavy-fermion compounds.

Measurement of the T20 component of tensor analyzing power for the incoherent π−-meson photoproduction on a deuteron

We present experimental results for T20 component of the tensor analyzing power for incoherent π− photoproduction on a deuteron. The experiment was performed on an internal tensor-polarized gas deuterium target of the VEPP-3 electron storage ring in 2021 using the proton-proton coincidence method. The data are compared with the results of numerical simulation.

Ionization and electron capture in O6+ + He collisions at 0.86, 1.5, 1.94 a.u. velocities

Using the projectile-ion-recoil-ion coincidence method, relative cross sections for single-electron capture, single ionization, double-electron capture, transfer ionization and double ionization in collisions of multiply charged O6+ ions with helium atoms have been measured at 0.86, 1.5, 1.94 a.u. velocities. Calculations based on the semi-classical over-barrier model in the framework of independent electron approximation is employed to discuss various competing reaction mechanisms. These results are also compared with other experimental and theoretical results available in the velocity range considered.

An overview of consensus models for group decision-making and group recommender systems

Group decision-making processes can be supported by group recommender systems that help groups of users obtain satisfying decision outcomes. These systems integrate a consensus-achieving process, allowing group members to discuss with each other on the potential items, adapt their opinions accordingly, and achieve an agreement on a selected item. Such a process, therefore, helps to generate group recommendations with a high satisfaction level of group members. Our article provides a rigorous review of the existing consensus approaches to group decision-making. These approaches are classified depending on the applied consensus models such as reference domain where a set of group members or items is selected for calculating consensus measures, coincidence method that calculates the consensus degree between group members depending on the coincidence concept, operators that aggregate user preferences, guidance measures where the consensus-achieving process is guided by different consensus measures, and recommendation generation and individual centrality that enhance the role of a moderator or a leader in the consensus-achieving process. Further consensus techniques for group decision-making in heterogeneous and large-scale groups are also discussed in this article. Besides, to provide an overall landscape of consensus approaches, we also discuss new consensus models in group recommender systems. These models attempt to improve basic aggregation strategies, further consider social relationship interactions, and provide group members with intuitive descriptions regarding the current consensus state of the group. Finally, we point out challenges and discuss open topics for future work.

The measurement of the half-life of the second excited state of 237Np with a new detector system and digital electronics

The half-life of the second excited state (5/2− at 59.54 keV) of 237Np was measured with high precision and reliability using the coincidence method with fast scintillators and a fully digital-based electronic data acquisition system. The alpha particle from an 241Am source was measured in coincidence with the gamma rays emitted by the daughter 237Np nucleus. This measurement also illustrates the use of new LYSO(Ce) scintillators in particle-gamma experiments.

PHASE FREQUENCY INTERPRETATION OF THE COINCIDENCE METHOD FOR FREQUENCY TO CODE CONVERSION

Context. The problem of fast conversion of radio signal frequency for monitoring the radial velocity of a moving object. The object of the study was the process of converting frequency into a code based on the coincidence method.
 Objective. The goal of the work is to improve the coincidence method for creating a new signal-to-code frequency converter without fixing the conversion time interval.
 Method. The coincidence method for converting the signal frequency into a code has been improved. The improved frequency conversion method, unlike the existing ones, consists in counting the number of complete phase cycles of the known and unknown signals during the time of double coincidence and asynchronous mode of hardware determination of the particle. The improved method has advantages in comparison with the method of an electro-counter frequency meter when determining the radial speed of objects and does not have a methodical error, which in an electro-counter frequency meter increases as the unknown frequency approaches the reference to 100%. However, the improved coincidence method compared to other versions has a hardware scheme for tracking the moments of coincidence and determining the fraction and does not require expensive and high-speed microprocessors to calculate the conversion results.
 Results. Based on the phase-frequency interpretation and the derived conversion equation and the proposed frequency-to-code conversion scheme using the coincidence method, a functional scheme of the frequency converter was developed. This made it possible to implement a 16-bit frequency converter in code on Intel’s MAX V series CPLD.
 Conclusions. The coincidence method for converting the signal frequency into a code received further development, which, unlike the existing ones, consists in counting the number of complete phase cycles of the known and unknown signals during the time of double coincidence and the asynchronous mode of hardware determination of the fraction.
 The influence of the frequency of signals on the time of a single measurement was studied using the coincidence method, as a result of which it was found that with an increase in the difference between the reference and unknown frequency, the time of a single measurement decreases.
 The obtained research results can be used for the development of high-speed means of converting the signal frequency into a binary code: in industrial tomography, radar and radio navigation for monitoring moving objects.

LiDAR-Derived Relief Typology of Loess Patches (East Poland)

The application of the automated analysis of remote sensing data processed into high-resolution digital terrain models (DTMs) using geographic information systems (GIS) tools provides a geomorphometric characterization of the diversity of the relief of loess patches over large areas. Herein, a quantitative classification of 79 loess patches with a total area of 3361 km2, distributed within the eastern part of the Polish Uplands belt, is carried out. A high-resolution 1 × 1 m DTM was generated from airborne laser scanning (ALS) data with densities ranging from 4 pts/m2 to 12 pts/m2, which was resampled to a resolution of 5 × 5 m for the study. This model was used to classify landform surfaces using the r.geomorphon (geomorphon algorithm) function in GRASS GIS software. By comparing the values in the neighborhood of each cell, a map of geomorphometric features (geomorphon) was obtained. The classification and typology of the relief of the studied loess patches was performed using GeoPAT2 (Geospatial Pattern Analysis Toolbox) software. Pattern signatures with a resolution of 100 × 100 m were extracted from the source data grid, and the similarity of geomorphological maps within the signatures was calculated and saved as a signature file and segment map using the spatial coincidence method. The distance matrix between each pair of segments was calculated, and the heterogeneity and isolation of the maps were generated. R system was used to classify the segments, which generated a dendrogram and a heat map based on the distance matrix. This made it possible to distinguish three main types and eight subtypes of relief. The morphometric approach used will contribute to a better understanding of the spatial variation in the relief of loess patches.

Performance test of a position sensitive planar germanium detector for phase-III DESPEC experiments

The position sensitivity of a planar segmented double-sided germanium strip detector, with 10 × 10 electrical segmentation in orthogonal directions, has been studied using the coincidence method. The coincidences were set up between an imaging scanner and the PSPGe (Position Sensitive Planar Germanium) detector using a positron source, 22Na, and analyzed by employing the Positron Annihilation Correlation principle. A collimated 241Am source scan was also performed to find position resolution along X and Y axes using low energy gamma-ray source. The primary objective of this work is to study the charge carrier transportation for gamma-ray interactions inside the PSPGe detector. In order to select the electrodes of interest and to obtain the pulse shapes for each event, two-dimensional images have been processed. The net charge induced on the surface of the electrode, calculated using the pulse shape analysis procedure, has been used to profile the position resolution and gamma interaction depth. The present study is an input for the deployment of PSPGe detector in the future decay spectroscopy experiments to be performed at the Facility for Antiproton and Ion Research (FAIR) in Germany. This work investigates the gamma interaction depth by calculating the rise-time of traces stored for each gamma interaction inside the detector volume, providing ≈1 mm resolution along the depth. The position resolution of the detector in lateral directions, determined using the amplitude difference of the transient charges, has also been found to be ≈1 mm.

Measuring the half-life of 215Po by low-level liquid scintillation counting

The half-life of short-lived 215Po was studied in a new experimental setup by means of liquid scintillation counting. The new value of 1.781 (5) ms was obtained by offline data analysis using the delayed coincidence method. Along with the half-life determination, a careful assessment of uncertainties was carried out. The result was compared with data available from the literature.

International comparison of activity measurements of a solution of 51Cr

Main textA bilateral comparison between LNE-LNHB, France and the RC POLATOM, Poland on activity measurements of the 51Cr solution was organized in 2022 as the EURAMET project No 1554 and registered as EURAMET.RI(II)-K2.Cr-51 key comparison. In both laboratories, primary activity measurements techniques based on 4π(LS)-γ coincidence and anti-coincidence counting methods were used. LNE-LNHB also performed indicative measurements in a large-well NaI(Tl) detector using the 4πγ method. The final result of the comparison in RC POLATOM was the weighted mean of the results of the 4π(LS)-γ coincidence method and the 4π(LS)-γ anti-coincidence method, and in the LNE-LNHB - the value obtained by the 4π(LS)-γ anti-coincidence method. The power-moderated mean of the final results values was calculated. An additional ampoule containing the same 51Cr solution was sent to the BIPM in order to link the results achieved in the bilateral comparison to the BIPM SIR reference system.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Standardisation of 18F using new portable 4πβ(LS) – λ coincidence detection system at ENEA-INMRI

This project concerned with the development at ENEA-INMRI of new in-situ 4πβ(LS) − λ coincidence detection system for activity measurement of the short half-life radionuclides used in Nuclear Medicine. The hardware of the new portable 4πβ(LS) − λ coincidence detection system was implemented at ENEA-INMRI, in collaboration with Catania University and INFN, by adding a gamma channel on the existing TDCR portable detector available at ENEA-INMRI. A new data analysis software was developed at CAEN, independently from an existing one elaborated at ENEA.INMRI, in order to analyse the data recorded in list-mode by the new detector equipped with the CAEN desktop digitizer DT5720. The activity for short half-life radionuclides used in nuclear medicine can be then computed. Two primary activity measurement TDCR and 4πβ(LS) − λ coincidence methods were then used to determine the activity of 18F at ENEA-INMRI. The TDCR parameter is measured for the 18F standard solution using both CAEN and ENEA-INMRI data analysis software.

Integration Methods as a Means of Improving the Level of Teachers’ Professional Training

This article suggests one of the possible ways of integrating teaching methods from the integration methods developed by the authors, namely: the integration based on the dominant teaching method. The article aims to substantiate the author’s methods of integrative teaching based on the dominant method and present the results of the approbation of these methods in higher schools. The project was implemented within the course “Medical Biophysics”. An integration algorithm as a dominant teaching method is proposed. The project contained several specific techniques. In the first specific method, the situational method is chosen as the dominant one. For the second one, the method of trials and coincidences is dominant. For diagnostics as a complex topic in medicine, physics, chemistry and other sciences, the problem method as dominant is dominant. In all methods, several other methods are gradually integrated into the dominant method, depending on the content and nature of the educational material. The practical significance of the project is to create algorithms for integrating teaching methods and the possibility of their transformation into other educational topics. The approbation shows an increase in the indicators of saving time and flexibility of knowledge.