• Journal of Sensor Science and Technology
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• v.7 no.4
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• pp.234-242
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• 1998

Changes in transmission and thermoluminescent characteristics were used in order to find out the optimum growth condition of CsI single crystal scintillators which were made relatively defect-free using Czochralski method. Impurity distribution in the crystals and the intensity and number of thermoluminescent glow peaks decreased as the process of crystallization was repeated. The direction of crystal growth turned out to be (110), the crystal structure of grown CsI was bee, and its lattice constant was found to be $4.568{\AA}$. The activation energy (trap depths) of CsI:3rd was 0.45 eV and its frequency factor was $5.18{\times}10^5\;sec^{-1}$.

• Journal of the Korean Society of Radiology
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• v.16 no.5
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• pp.499-504
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• 2022

Positron emission tomography (PET) uses a very small scintillator to achieve exellent spatial resolution. Therefore, in this study, a PET system using a scintillator to 0.8 mm size was designed and the performance was evaluated. Anihilation radiation was generated from the center of the field of view (FOV) to the outskirts at intervals of 10 mm, and counted simultaneously. The image was reconstructed using the coincidence data, and the spatial resolution was calculated by acquiring the full width at half maximum through the profile. The spatial resolution at the center of the FOV was 1.02 mm, showing a very good result, and the spatial resolution decreased as it was located at the outer edge. To evaluate the phantom image, the Derenzo phantom was constructed to acquire the image, and the degree of classification between radiation sources was evaluated through profile analysis. The result showed that the distance between the radiation sources was larger than the spatial resolution of the radiation sources at each location, and it was confirmed that the radiation sources were distinguished through this. When the PET system designed in this study is applied to PET for small animals, it is considered that excellent performance can be secured through the characteristic of very good spatial resolution.

• Korean Journal of Optics and Photonics
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• v.18 no.4
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• pp.241-245
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• 2007

In this study, a two-dimensional fiber-optic radiation sensor has been developed using water-equivalent organic scintillators for photon beam therapy dosimetry. Two-dimensional photon beam distributions and percent depth doses(PDD) are measured according to the energies and field sizes of the photon beam. This sensor has many advantages such as high resolution, real-time measurement and ease of calibration over conventional radiation measurement devices.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.233-238
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• 2003

Several types of gamma-ray sensors were constructed by packing different numbers of fibers into aluminum tubes, and tested to detect the $^137Cs$ gamma ray. It has been found from this investigation that tapered fibers can be more efficient to collect the lights produced inside the sensor and transfer them into the transmitting fiber in order to predict the functioning of the tapered fiber, tapered plastic scintillators, composed of polystyrene with minute amount of dPOPOP and PPO or dPBD, were fabricated and tested for the detection of gamma rays from 1.0 1.5 3.0 5.0 ${\mu}Ci$ $^137Cs$ sources, and the pulse hight spectrum and the relationship between the radioactivity and the total counts are analyzed. It has been found from this study that the tapered scintillating optical fiber, if manufactured, can be practically applied to the development of gamma-ray sensors which can be deployed In ${\mu}Ci$-level radiation fields

• Journal of Radiation Protection and Research
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• v.31 no.3
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• pp.123-128
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• 2006

A small radiation detection system is necessary for the direct characterization of alpha/beta-ray contamination inside pipes generated during the decommission of a nuclear facility. In this work, the new type phoswich detector consisting of the ZnS(Ag) and plastic scintillator for ${\alpha}/{\beta}$ simultaneous counting was designed as part of a development of a equipment capable of monitoring radiological contamination inside pipes. The optimum counting conditions in dimensions of scintillator and a detection system were experimentally confirmed and a performance of alpha/beta-ray discrimination was evaluated. As a result, optimum conditions of a detector suitable for monitoring radiological contamination inside pipes and a feasibility of application to pipe-inside were confirmed.

• Analytical Science and Technology
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• v.18 no.6
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• pp.495-499
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• 2005

Notwithstanding antipathies against radiation, radiations are extensively used in various fields with development of the radiation technology. In order to safely manage such radiation it is necessary for development of the radiation measurement materials. In this paper a thin film type of plastic scintillator using in the contamination measurement devices was prepared. The plastic organic scintillator was prepared by simple solvent methods. It was possible to prepare in easy way and in various forms. The polysulfone which has high transparency and solubility was chosen. As the radiation measurement scintillator, the optical properties and radiation detection abilities were estimated.

• Journal of the Korean Society of Radiology
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• v.17 no.2
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• pp.201-206
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• 2023

In order to improve the spatial resolution of the gamma camera, the size of the hole in the collimator must be reduced, so the sensitivity is reduced. In order to improve the sensitivity, the size of the hole must be increased, and thus the spatial resolution is reduced. In other words, spatial resolution and sensitivity show opposite characteristics. In this study, a gamma camera was designed to improve both spatial resolution and sensitivity. In order to obtain higher sensitivity in gamma cameras with the same spatial resolution, the structure of the scintillator was designed differently from the existing system. A scintillation pixel was used, and a partition wall was placed between the scintillation pixels to prevent incident gamma rays from being transmitted to other scintillation pixels to interact. Geant4 Application for Tomographic Emission (GATE) simulation was performed to evaluate the performance of the designed gamma camera. When the same sensitivity as the block-type scintillator was obtained, the spatial resolution increased by 16.5%, and when the same spatial resolution was obtained, the sensitivity increased by 61.5%. It is considered that the use of the gamma camera designed in this study can improve the sensitivity compared to the existing system while securing excellent spatial resolution.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2007.05a
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• pp.38-39
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• 2007

• Journal of Radiation Protection and Research
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• v.28 no.3
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• pp.173-182
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• 2003

A prototype liquid scillatillator system for measurement of multiple beta-labeled mixtures was developed and its characteristic was investigated. The signal processing system consists of two photomultiplier tubes and the coincident count circuit. The characteristic of the system was analyzed using 4 beta-labeled samples $(^3H,\;^{14}C,\;^{36}Cl\;and\;^{90}Sr)$. Beta spectra from the samples were obtained without radiation shielding, and the detection limits for each nuclides were estimated based on the spectra. The estimated detection limits were compared to the legal regulation values. It is found that the liquid radioactive nuclides are detectable well below the legal regulation values.

• Journal of Sensor Science and Technology
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• v.23 no.1
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• pp.29-34
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• 2014

A dosimeter using tissue-equivalent scintillator by photon-counting method was developed and evaluated in its performance. The dosimeter is portable and can be operated by low power from lap-top computer. A data-acquisition software of the dosimeter system was developed by Labwindows/CVI based on Windows. The energy to channel ratio for energy calibration was 0.839 keV/ch. obtained from pulse height spectrum of $^{137}Cs$ and $^{60}Co$ gamma-ray. Using the dosimeter system, the absorbed dose of environmental radiation in Gyungju was 0.18 ${\mu}Sv/h$.