• Title, Summary, Keyword: Radiation Detection Energy Response

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Distribution of ddr (DNA damage response) Genes among Species of Deinococcus

  • Lim, Sangyong;Jung, Sunwook;Joe, Minho;Kim, Dongho
    • Journal of Radiation Industry
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    • v.4 no.3
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    • pp.289-295
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    • 2010
  • The bacterium Deinococcus radiodurans is one of the most resistant organisms to the effects of ionizing radiation and other DNA-damaging agents. In this study, distributions of 10 ddr (DNA damage response) genes were investigated in 8 species of Deinococcus by polymerase chain reaction (PCR). We have compared the sequences of ddr genes of D. radiodurans, D. geothermalis and D. deserti, and selected primers which are suitable for the detection of ddr in different species of Deinococcus. A sequence homology search and PCR assay showed that ddrO, which encodes a global regulator of the radiation-desiccation response, was most well conserved in the Deinococcus lineage.

Development of Electronic Personal Dosimeter with Hybrid Preamplifier using Semiconductor Detector (반도체 검출기를 이용한 Hybrid 전치증폭기형 전자식 개인선량계 개발)

  • Lee, B.J.;Kim, B.H.;Chang, S.Y.;Kim, J.S.;Rho, S.R.
    • Journal of Radiation Protection and Research
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    • v.27 no.1
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    • pp.51-57
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    • 2002
  • An electronic personal dosimeter(EPD) with hybrid type preamplifier adopting a semiconductor detector as a radiation detector has been developed, manufactured and test-evaluated. The radiation detection characteristics of this EPD has been performance-tested by using a reference photon radiation field. After several test-irradiations to a $^{137}Cs$ gamma radiation source the radiation detection sensitivity of this EPD appeared to be $3.8\;cps/Gy{\cdot}h^{-1}$. The linearity of radiation response was kept within 8% of the dose equivalent ranges of $10{\mu}Sv{\sim}4Sv$ and the angular dependence was under less than 4% in angles of ${\pm}60^{\circ}$. It was confirmed that the energy response range was in $60{\sim}1,250keV$ given in the ISO standard. This EPD satisfied the international criteria for the EPD in the mechanical and the environmental performance test for 9 test categories according to IEC 61526.

CHARACTERISTICS OF FABRICATED SiC RADIATION DETECTORS FOR FAST NEUTRON DETECTION

  • Lee, Cheol-Ho;Kim, Han-Soo;Ha, Jang-Ho;Park, Se-Hwan;Park, Hyeon-Seo;Kim, Gi-Dong;Park, June-Sic;Kim, Yong-Kyun
    • Journal of Radiation Protection and Research
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    • v.37 no.2
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    • pp.70-74
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    • 2012
  • Silicon carbide (SiC) is a promising material for neutron detection at harsh environments because of its capability to withstand strong radiation fields and high temperatures. Two PIN-type SiC semiconductor neutron detectors, which can be used for nuclear power plant (NPP) applications, such as in-core reactor neutron flux monitoring and measurement, were designed and fabricated. As a preliminary test, MCNPX simulations were performed to estimate reaction probabilities with respect to neutron energies. In the experiment, I-V curves were measured to confirm the diode characteristic of the detectors, and pulse height spectra were measured for neutron responses by using a $^{252}Cf$ neutron source at KRISS (Korea Research Institute of Standards and Science), and a Tandem accelerator at KIGAM (Korea Institute of Geoscience and Mineral Resources). The neutron counts of the detector were linearly increased as the incident neutron flux got larger.

A Study of Interface Layer on CdZnTe Radiation Sensor for Potable Isotope Identifier (이동형 핵종 분석 장치용 CZT 반도체 검출기의 완충전극에 대한 연구)

  • Cho, Yun Ho;Park, Se-Hwan;Kim, Yong Kyun;Ha, Jang Ho
    • Journal of Radiation Industry
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    • v.5 no.1
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    • pp.95-99
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    • 2011
  • The electrical and mechanical properties of electrode for radiation detection are very important. In general, Au electrode and CZT crystal are combined to form ohmic contacts, and the best energy resolution is shown at the Au electrode. The metal contacts are fabricated by electroless deposition method, sputtering deposition method and thermal evaporation method. The electrode fabrication is easy with use of the thermal evaporation method, while an adhesive strength is weak. Thus interface materials such as Ag, Al and Ni were investigated to overcome defects generated by the this method. The thickness of the interface material between the Au electrode and the CZT crystal was 100 Angstroms, the Au electrode with thickness of 400 Angstroms was deposited. The Al+Au electrode is shown that the results of current-voltage and radiation response are similar to results of Au electrode.

A Nuclear Event Detectors Fabrication and Verification for Detection of a Transient Radiation (과도방사선 검출을 위한 핵폭발 검출기 제작 및 검증)

  • Jeong, Sang-Hun;Lee, Seung-Min;Lee, Nam-Ho;Kim, Ha-Chul;Cho, Seong-Ik
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.5
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    • pp.639-642
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    • 2013
  • In this paper, proposed NED(nuclear event detectors) for detection of a transient radiation. Nuclear event detector was blocked of power temporary for defence of critical damage at a electric device when a induced transient radiation. Conventional NED consist of BJT, resistors and capacitors. The NED supply voltage of 5V and MCM(Multi Chip Module) structures. The proposed NED were designed for low supply voltage using 0.18um CMOS process. The response time of proposed NED was 34.8ns. In addition, pulse radiation experiments using a electron beam accelerator, the output signal has occurred.

Influence of the Thin-Film Ag Electrode Deposition Thickness on the Current Characteristics of a CVD Diamond Radiation Detector

  • Ban, Chae-Min;Lee, Chul-Yong;Jun, Byung-Hyuk
    • Journal of Radiation Protection and Research
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    • v.43 no.4
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    • pp.131-136
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    • 2018
  • Background: We investigated the current characteristics of a thin-film Ag electrode on a chemical vapor deposition (CVD) diamond. The CVD diamond is widely recognized as a radiation detection material because of its high tolerance against high radiation, stable response to various dose rates, and good sensitivity. Additionally, thin-film Ag has been widely used as an electrode with high electrical conductivity. Materials and Methods: Considering these properties, the thin-film Ag electrode was deposited onto CVD diamonds with varied deposition thicknesses (${\fallingdotseq}50/98/152/257nm$); subsequently, the surface thickness, surface roughness, leakage current, and photo-current were characterized. Results and Discussion: The leakage current was found to be very low, and the photo-current output signal was observed as stable for a deposited film thickness of 98 nm; at this thickness, a uniform and constant surface roughness of the deposited thin-film Ag electrode were obtained. Conclusion: We found that a CVD diamond radiation detector with a thin-film Ag electrode deposition thickness close to 100 nm exhibited minimal leakage current and yielded a highly stable output signal.

Development of Radiation Sensor Based on Array SiPM for Measurement of Radioactive Contamination in Effluent (방류수의 방사능 오염 측정을 위한 배열형 SiPM 기반 방사선 검출 센서 제작)

  • Kim, Jeongho;Park, Hyemin;Joo, Koansik
    • Journal of Sensor Science and Technology
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    • v.27 no.4
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    • pp.232-236
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    • 2018
  • A radiation detection sensor was developed and characterized by combining three types of CsI(Tl) scintillators and an array-type SiPM to detect the radioactive contamination of discharged water in real time. The characterization results showed that type 3 exhibited the most desirable characteristics in response linearity (R-square: 0.97889) according to detection sensitivity and incident radiation dose. Furthermore, in terms of spectral characteristics, type 3 exhibited 16.54% at 0.356 MeV (the emission gamma ray energy of $^{133}Ba$), 10.28% at 0.511 MeV (the emission gamma ray energy of $^{22}Na$), 9.68% at 0.356 MeV (the emission gamma ray energy of $^{137}Cs$), and 2.55% and 4.80% at 1.173 MeV and 1.332 MeV (the emission gamma ray energies of $^{60}Co$), respectively. These measurements confirmed the good energy characteristics. The results were used to evaluate the spectral characteristics and energy linearity in a mixed source using type 3 with the best detection characteristics. It was confirmed that the gamma ray peaks of $^{133}Ba$, $^{22}Na$, $^{137}Cs$, and $^{60}Co$ were well resolved. Moreover, it was confirmed that R-square, which is an indicator of energy linearity, was 0.99986. This indicates a good linearity characteristic. Based on this study, further commercialization studies will contribute to measurements in real time and to the management of the contamination caused by radioactive wastewater or radioactive material leakage, which originate from facilities that use radioactive isotopes or care facilities.

A Review of Dose Rate Meters as First Responders to Ionising Radiation

  • Akber, Aqeel Ahmad;Wiggins, Matthew Benfield
    • Journal of Radiation Protection and Research
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    • v.44 no.3
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    • pp.97-102
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    • 2019
  • Background: Dose rate meters are the most widely used, and perhaps one of the most important tools for the measurement of ionising radiation. They are often the first, or only, device available to a user for an instant check of radiation dose at a certain location. Throughout the world, radiation safety practices rely strongly on the output of these dose rate meters. But how well do we know the quality of their output? Materials and Methods: This review is based on the measurements 1,158 commercially available dose rate meters of 116 different makes and models. Expected versus the displayed dose patterns and consistency was checked at various dose rates between $5{\mu}Gy{\cdot}h^{-1}$ and $2mGy{\cdot}h^{-1}$. Samples of these meters were then selected for further investigation and were exposed to radiation sources covering photon energies from 50 keV to 1.5 MeV. The effect of detector orientation on its reading was also investigated. Rather than focusing on the angular response distribution that is often reported by the manufacturer of the device, this study focussed on the design ergonomics i.e. the angles that the operator will realistically use to measure a dose rate. Results and Discussion: This review shows the scope and boundaries of the ionising radiation dose rate estimations that are made using commonly available meters. Observations showed both inter and intra make and model variations, occasional cases of instrument failure, instrument walk away, and erroneous response. Conclusion: The results indicate the significance of selecting and maintaining suitable monitors for specific applications in radiation safety.

Development and Performance of a Hand-Held CZT Detector for In-Situ Measurements at the Emergency Response

  • Ji, Young-Yong;Chung, Kun Ho;Kim, Chang-Jong;Yoon, Jin;Lee, Wanno;Choi, Geun-Sik;Kang, Mun Ja
    • Journal of Radiation Protection and Research
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    • v.41 no.2
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    • pp.87-91
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    • 2016
  • Background: A hand-held detector for an emergency response was developed for nuclide identification and to estimate the information of the ambient dose rate in the scene of an accident as well as the radioactivity of the contaminants. Materials and Methods: To achieve this, the most suitable sensor was first selected as a cadmium zinc telluride (CZT) semiconductor and the signal processing unit from a sensor and the signal discrimination and storage unit were successfully manufactured on a printed circuit board. Results and Discussion: The performance of the developed signal processing unit was then evaluated to have an energy resolution of about 14 keV at 662 keV. The system control unit was also designed to operate the CZT detector, monitor the detector, battery, and interface status, and check and transmit the measured results of the ambient dose rate and radioactivity. In addition, a collimator, which can control the inner radius, and the airborne dust sampler, which consists of an air filter and charcoal filter, were developed and mounted to the developed CZT detector for the quick and efficient response of a nuclear accident. Conclusion: The hand-held CZT detector was developed to make the in-situ gamma-ray spectrometry and its performance was checked to have a good energy resolution. In addition, the collimator and the airborne dust sampler were developed and mounted to the developed CZT detector for a quick and efficient response to a nuclear accident.

Design and Implementation of an optical wavelength analyzer (CCD 카메라를 이용한 방사선 탐지기의 영상화 기술 연구)

  • Park, Sung-hoon;Park, Jong Won;Lee, Nam-ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.811-813
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    • 2013
  • In order to measure the radiation, there are types of sensors plurality. I was using the detection method and sensitivity of the CCD sensor in the scintillator and collimator in the sensor. In this study, in order to detect radiation using a CCD sensor with high resolution, by measuring the radiation dose by processing the visible light generated in response to radiation of the image coming into the CCD in the scintillator in space it is to present a pointer that radiation comes out most. It is intended to imaging by calculation of the distance to the radiation source to the implementation of the stereo camera system video in the future.

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