INVESTIGATING THE CHARACTERISTICS OF LARGE-VOLUME PVT SCINTILLATION DETECTORS IN THE RADIATION PORTAL MONITORS USING MONTE CARLO SIMULATIONS

2021 ◽  
pp. 52-59
Author(s):  
Cao Van Hiep
Keyword(s):  
Detection Efficiency ◽  
Incident Angle ◽  
Energy Spectra ◽  
Scintillation Detectors ◽  
Calibration Source ◽  
Simulation Code ◽  
Large Size ◽  
Detector Distance ◽  
Determination Process ◽  
Absolute Efficiency

This paper presents the characteristics determination process of the large-size Polyvinyl Toluene (PVT) scintillation detectors using MCNP5 simulation code. The energy spectra using a 137Cs calibration source, absolute efficiency in the energy range of 50 ÷ 3000 keV, and the angular response of the EJ-200 50×50×5 cm3 and 25×25×5cm3 are investigated. The simulated energy spectra are in good agreement with the experimental spectra. The results of determining the absolute efficiency show that the EJ-200 50×50×5 cm3 and 25×25×5cm3 plastic detectors have detection efficiencies of 16,3% and 9,2%, respectively, at 10cm source-to-detector distance, and down to 0,6% and 0,17% at 100 cm source-to-detector distance. The angular responses of the detectors show that the detection efficiency value reached ≥ 90% of the maximum value with the incident angle less than 5π/6. The results can be applied in the process of design optimization of plastic-based radiation portal monitors.

scholarly journals RESPONSE OF CsI:Pb SCINTILLATOR CRYSTAL TO NEUTRON RADIATION

2018 ◽  
Vol 170 ◽  
pp. 01005
Author(s):  
Maria da Conceição Costa Pereira ◽  
Tufic Madi Filho ◽  
José Roberto Berretta ◽  
José Patrício Náhuel Cárdenas ◽  
Antonio Carlos Iglesias Rodrigues
Keyword(s):  
Light Emission ◽  
Detection Efficiency ◽  
Light Output ◽  
Neutron Detection ◽  
Neutron Radiation ◽  
Cesium Iodide ◽  
Great Effort ◽  
Operating Voltage ◽  
Simulation Code ◽  
Inorganic Scintillators

The helium-3 world crisis requires a development of new methods of neutron detection to replace commonly used 3He proportional counters. In the past decades, great effort was made to developed efficient and fast scintillators to detect radiation. The inorganic scintillator may be an alternative. Inorganic scintillators with much higher density should be selected for optimal neutron detection efficiency taking into consideration the relevant reactions leading to light emission. These detectors should, then, be carefully characterized both experimentally and by means of advanced simulation code. Ideally, the detector should have the capability to separate neutron and gamma induced events either by amplitude or through pulse shape differences. As neutron sources also generate gamma radiation, which can interfere with the measurement, it is necessary that the detector be able to discriminate the presence of such radiation. Considerable progress has been achieved to develop new inorganic scintillators, in particular increasing the light output and decreasing the decay time by optimized doping. Crystals may be found to suit neutron detection. In this report, we will present the results of the study of lead doped cesium iodide crystals (CsI:Pb) grown in our laboratory, using the vertical Bridgman technique. The concentration of the lead doping element (Pb) was studied in the range 5х10-4 M to 10-2 M . The crystals grown were subjected to annealing (heat treatment). In this procedure, vacuum of 10-6 mbar and continuous temperature of 350°C, for 24 hours, were employed. In response to neutron radiation, an AmBe source with energy range of 1 MeV to 12 MeV was used. The activity of the AmBe source was 1Ci Am. The fluency was 2.6 х 106 neutrons/second. The operating voltage of the photomultiplier tube was 1700 V; the accumulation time in the counting process was 600 s and 1800 s. The scintillator crystals used were cut with dimensions of 20 mm diameter and 10 mm height.

scholarly journals Calibration of the Absolute Efficiency of Well-Type NaI(Tl) Scintillation Detector in 0.121–1.408 MeV Energy Range

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Dalal Al Oraini
Keyword(s):  
Energy Range ◽  
Sodium Iodide ◽  
Detection Efficiency ◽  
Solid Angle ◽  
Radioactive Isotopes ◽  
Activity Measurements ◽  
Absolute Efficiency ◽  
Sodium Iodide Detector ◽  
The Absolute ◽  
Detector Material

Well-type NaI(Tl) detectors are beneficial for low-level photon activity measurements because of the near 4π solid angle that can be gained with them. The detection efficiency can differ with the source-to-detector system geometries, the absorption of the photon in the detector material, and attenuation layers in front of the detector face. For these purposes, the absolute efficiency and the coincidence corrections of the well-type sodium iodide detector have been measured at 0.121–1.408 MeV energy range (obtained from 152Eu, 137Cs, and 60Co radioactive isotopes). The covenant between the experimental (present work) and the published theoretical values is good, with the high discrepancies being less than 1%.

scholarly journals A Geant4 simulation code for simulating optical photons in SPECT scintillation detectors

2009 ◽  
Vol 4 (07) ◽  
pp. P07002-P07002 ◽  
Author(s):  
S Lo Meo ◽  
P Bennati ◽  
M N Cinti ◽  
N Lanconelli ◽  
F L Navarria ◽  
...  
Keyword(s):  
Geant4 Simulation ◽  
Scintillation Detectors ◽  
Simulation Code ◽  
Optical Photons

scholarly journals Detection Efficiency of NaI(Tl) Detector in 511–1332 keV Energy Range

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
I. Akkurt ◽  
K. Gunoglu ◽  
S. S. Arda
Keyword(s):  
Quality Control ◽  
Energy Resolution ◽  
Detection Efficiency ◽  
Medical Physics ◽  
Experimental System ◽  
Absolute Efficiency ◽  
Analytical Result ◽  
Required Quality ◽  
System Gamma ◽  
Peak To Valley Ratio

As it is important to obtain accurate analytical result in an experimental research, this required quality control of the experimental system. Gamma spectrometry system can be used in a variety of different fields such as radiation and medical physics. In this paper the absolute efficiency, peak to valley ratio, and energy resolution of a3′′×3′′NaI(Tl) detector were determined experimentally for 511, 662, 835, 1173, 1275, and 1332 keV photon energies obtained from22Na,54Mn,60Co, and137Cs radioactive sources.

scholarly journals Holographic Near-Eye 3D Display Method Based on Large-Size Hologram

2021 ◽  
Vol 8 ◽  
Author(s):  
Su-Juan Liu ◽  
Ning-Tao Ma ◽  
Ping-Ping Li ◽  
Di Wang
Keyword(s):  
Incident Angle ◽  
Linear Structure ◽  
Reconstructed Image ◽  
Spatial Light Modulators ◽  
Image Point ◽  
Viewing Angle ◽  
3D Display ◽  
Light Modulators ◽  
Large Size ◽  
Tiling System

In this paper, we propose a holographic near-eye 3D display method based on large-size computer-generated hologram (CGH). The reconstructed image with a large viewing angle is obtained by using a time multiplexing and spatial tiling system. The large-size CGHs are generated and they record the information of the 3D object from different angles. The CGHs are reproduced at different moments. For a certain reconstructed moment, three spatial light modulators (SLMs) spatially spliced into a linear structure are used to load a single CGH. The diffraction boundary angle of the reconstructed light forming each image point is equal to the maximum diffraction angle of the SLM, so the viewing angle of the image generated by the CGH is enlarged. For different CGHs, the incident angle of reconstructed light is changed. Through time multiplexing, the reconstructed images of the CGHs are combined into a reconstructed image whose viewing angle is further enlarged. Due to the large viewing angle of the reconstructed image, the proposed method has unique advantages in near-eye display. The feasibility of the proposed method is proved by experimental results.

scholarly journals Automated structure refinement of macromolecular assemblies from cryo-EM maps using Rosetta

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Ray Yu-Ruei Wang ◽  
Yifan Song ◽  
Benjamin A Barad ◽  
Yifan Cheng ◽  
James S Fraser ◽  
...  
Keyword(s):  
Structure Refinement ◽  
Atomic Resolution ◽  
Large Radius ◽  
Macromolecular Assemblies ◽  
Automated Method ◽  
Large Size ◽  
Biological Phenomena ◽  
Determination Process ◽  
Improve Model ◽  
Model Geometry

Cryo-EM has revealed the structures of many challenging yet exciting macromolecular assemblies at near-atomic resolution (3–4.5Å), providing biological phenomena with molecular descriptions. However, at these resolutions, accurately positioning individual atoms remains challenging and error-prone. Manually refining thousands of amino acids – typical in a macromolecular assembly – is tedious and time-consuming. We present an automated method that can improve the atomic details in models that are manually built in near-atomic-resolution cryo-EM maps. Applying the method to three systems recently solved by cryo-EM, we are able to improve model geometry while maintaining the fit-to-density. Backbone placement errors are automatically detected and corrected, and the refinement shows a large radius of convergence. The results demonstrate that the method is amenable to structures with symmetry, of very large size, and containing RNA as well as covalently bound ligands. The method should streamline the cryo-EM structure determination process, providing accurate and unbiased atomic structure interpretation of such maps.

Lateral distribution and energy spectra of high-energy muons in cosmic-ray air showers

1990 ◽  
Vol 68 (1) ◽  
pp. 41-48 ◽  
Author(s):  
D. K. Basak ◽  
S. K. Sarkar ◽  
N. Mukherjee ◽  
S. Sanyal ◽  
B. Ghosh ◽  
...  
Keyword(s):  
Size Range ◽  
Detection Efficiency ◽  
Cosmic Ray ◽  
High Energy ◽  
Lateral Distribution ◽  
Energy Spectra ◽  
Recent Experimental Data ◽  
Air Showers ◽  
Shower Size ◽  
Primary Composition

The energy spectra and the lateral distribution of muons in cosmic-ray air showers, in the size range 104–106 particles as measured by two magnetic spectrographs each of full detection efficiency for muons in the energy range 2.5–500 GeV, are presented along with the derived muon size vs. shower size results. Comparisons with similar recent experimental data and calculations are given to infer the cosmic-ray primary composition.

scholarly journals Semiempirical Efficiency Calibration in Semiconductor HPGe Gamma-Ray Spectroscopy

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Jelena Krneta Nikolić ◽  
Milica Rajačić ◽  
Dragana Todorović ◽  
Marija Janković ◽  
Nataša Sarap ◽  
...  
Keyword(s):  
Measurement Uncertainty ◽  
Environmental Protection ◽  
Gamma Ray ◽  
Detection Efficiency ◽  
Calibration Source ◽  
Semiempirical Approach ◽  
Hpge Detectors ◽  
Gamma Ray Spectroscopy ◽  
Measured Sample

One of the main problems in quantitative gamma-ray spectroscopy is the determination of detection efficiency, for different energies, source-detector geometries, and composition of samples or sources. There are, in principle, three approaches to this issue: experimental, numerical, and semiempirical. Semiempirical approach is based on the calculation of the efficiency for the measured sample on the basis of an experimental efficiency measured on the same detector, but with a calibration source that can be of different size, geometry, density, or composition—the so-called efficiency transfer. The aim of this paper is to analyze the semiempirical approach, using EFFTRAN and MEFFTRAN software as a typical example. These software were used in the Department of Radiation and Environmental Protection, Vinča Institute of Nuclear Sciences, on three HPGe detectors. The results were compared to the experimentally obtained efficiency, and further validation is performed by measuring reference materials issued within the framework of several interlaboratory intercomparisons. The analysis of the results showed that the efficiency transfer produces good results with the discrepancies within the limits of the measurement uncertainty. Also, for intercomparison measurement, utest criterion for the trueness of the result was applied showing that the majority of the obtained results were acceptable. Some difficulties were identified, and the ways to overcome them were discussed.

scholarly journals Automated structure refinement of macromolecular assemblies from cryo-EM maps using Rosetta

2016 ◽  
Author(s):  
Ray Yu-Ruei Wang ◽  
Yifan Song ◽  
Benjamin A Barad ◽  
Yifan Cheng ◽  
James S Fraser ◽  
...  
Keyword(s):  
Structure Refinement ◽  
Atomic Resolution ◽  
Large Radius ◽  
Macromolecular Assemblies ◽  
Automated Method ◽  
Large Size ◽  
Biological Phenomena ◽  
Determination Process ◽  
Improve Model ◽  
Model Geometry

AbstractCryo-EM has revealed many challenging yet exciting macromolecular assemblies at near-atomic resolution (3-4.5Å), providing biological phenomena with molecular descriptions. However, at these resolutions accurately positioning individual atoms remains challenging and may be error-prone. Manually refining thousands of amino acids – typical in a macromolecular assembly – is tedious and time-consuming. We present an automated method that can improve the atomic details in models manually built in near-atomic-resolution cryo-EM maps. Applying the method to three systems recently solved by cryo-EM, we are able to improve model geometry while maintaining or improving the fit-to-density. Backbone placement errors are automatically detected and corrected, and the refinement shows a large radius of convergence. The results demonstrate the method is amenable to structures with symmetry, of very large size, and containing RNA as well as covalently bound ligands. The method should streamline the cryo-EM structure determination process, providing accurate and unbiased atomic structure interpretation of such maps.

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