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An investigation of 60Co gamma radiation-induced effects on the properties of nanostructured α-MoO3 for the application in optoelectronic and photonic devices
摘要： Gamma ray has sufficient energy to ionize and displace of atoms when interacts with optoelectronic and photonic devices that are placed at γ-radiation exposure environment, can be exposed to gamma radiation, resulting the alteration of the physical properties and hence the performances of devices. A comprehensive investigation of physical properties of the semiconductor materials under the influence of gamma radiation is essential for the effective design of devices for the application in the radiation exposure environment. In this article, a potential candidate for optoelectronic and photonic devices, orthorhombic MoO3 nanoparticles with average crystallite size of 135.31 nm successfully synthesized by hydrothermal method. Then, the properties of nanoparticles exposed to low (10 kGy) and high (120 kGy) absorbed dose of γ-rays from 60Co source were characterized by XRD, FESEM, FTIR and UV–Vis–NIR spectrophotometer and effects of absorbed doses was investigated for the first time. A significant change is observed in different physical properties of α-MoO3 nanoparticles after gamma exposure. The XRD patterns reveal the average crystallite size, intensity and the degree of crystallinity decrease for low dose (10 kGy) and increases for high dose (120 kGy). The calculated average crystallite size exposed to low and high doses are 127.79 nm and 136 nm, respectively. The lattice strain and dislocation density, however, shows the opposite trend of crystallite size with absorbed doses. This result is good evidence for the deterioration of crystallinity for low dose and improvement for high dose. The FESEM results reveal the significant effects of gamma doses on the micrographs of layered structure and on grain size. The optical studies disclose that band gap increases gradually from 2.78 to 2.90 eV, this behavior is associated with the reduction of electronic localized states. These results suggest that α-MoO3 nanoparticles could tolerate high doses of gamma radiation, making it a promising candidate for optoelectronic and photonic devices for γ-ray exposure environment applications.
关键词： Optoelectronic and photonic devices,α-MoO3 nanoparticles,Co-60 gamma radiation,Optical bandgap,Structural properties
更新于2025-10-22 19:40:53
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Development and characterization of air kerma cavity standard
摘要： Ionization chambers are the most common detectors for precise measurements such as these required in radiation protection and radiotherapy. This paper presents the design, development and characterization of a new graphite–walled cavity ionization chamber used as a primary standard for air kerma rate for 137Cs and 60Co gamma radiation of the Central Office of Measures (GUM). The paper describes particularly methods for a cavity volume determination and the cavity volume relation to an electric field. The various correction factors to be applied to the primary standards and their determination by experimental and Monte Carlo methods are discussed. Re–evaluation of the standard according to the recommendations of ICRU90 Report for the new primary standard is presented. A typical uncertainty budget for the graphite-walled cavity ionization chamber as a primary standard for air kerma rate for gamma radiation is presented and results of internal comparisons between standards are summarized and discussed.
关键词： ionization chamber,air kerma cavity standard,Monte Carlo simulation,gamma radiation
更新于2025-09-23 15:23:52
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[IEEE 2018 4th International Conference on Devices, Circuits and Systems (ICDCS) - Coimbatore, India (2018.3.16-2018.3.17)] 2018 4th International Conference on Devices, Circuits and Systems (ICDCS) - Comparative Study of CMOS based Dosimeters for Gamma Radiation
摘要： In this paper, a quantitative comparison study of the CMOS based Double Gate RADFET, Gate All Around (GAA) RADFET, Junctionless Double Gate (JL-DG) RADFET dosimeter and their electrical performance has been carried out. Gamma radiation Model of Sentaurus 3D Device simulator has been used to investigate the trapping detrapping of electron hole due to the moderate dose radiation environment. The impact of the total dose on the threshold voltage and drain current has been addressed. The obtained results indicate improvement in the subthreshold parameters of JL DG RADFET as compared to the conventional DG RADFET and GAA RADFET dosimeter.
关键词： Threshold Voltage,Sentaurus TCAD,JL DG RADFET,DG RADFET,Gamma Radiation Model,GAA MOSFET
更新于2025-09-19 17:15:36
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Evaluation of Uncertainty Measurement of Radionuclides Minimum Detectable Activity in Large Plastic Scinllators
摘要： This work is devoted to the evaluation of the measurement uncertainty of minimum detectable activity (MDA) for 137Cs on its gamma radiation with large plastic scintillators (PS) used in the portal monitors (PM). The influence of scintillators volume and irradiation geometry on the MDA evaluation of the measurement uncertainty was studied. It is shown that the estimated expanded MDA measurement uncertainty interval on 137Cs is 21—23 per cent. The absolute value of the MDA measurement uncertainty when changing geometry of irradiation increases 10 times. Change in the volumes of the examined PS causes a change of MDA measurement uncertainty within 10 per cent.
关键词： gamma radiation,MDA,portal monitor,PS scintillator,detector,uncertainty of MDA
更新于2025-09-19 17:13:59
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Effective production of gammas, positrons, and photonuclear particles from optimized electron acceleration by short laser pulses in low-density targets
摘要： Electron acceleration has been optimized based on 3D particle-in-cell simulations of a short laser pulse interacting with low-density plasma targets to find the pulse propagation regime that maximizes the charge of high-energy electron bunches. This regime corresponds to laser pulse propagation in a self-trapping mode where the diffraction divergence is balanced by the relativistic nonlinearity such that relativistic self-focusing on the axis does not happen and the laser beam radius stays unchanged during pulse propagation in a plasma over many Rayleigh lengths. Such a regime occurs for a near-critical density if the pulse length considerably exceeds both the plasma wavelength and the pulse width. Electron acceleration occurs in a traveling cavity filled with a high-frequency laser field and a longitudinal electrostatic single-cycle field (“self-trapping regime”). Monte Carlo simulations demonstrated that a high electron yield allows an efficient production of gamma radiation, electron–positron pairs, neutrons, and even pions from a catcher-target.
关键词： electron acceleration,photonuclear particles,laser pulse,gamma radiation,positrons,low-density plasma
更新于2025-09-12 10:27:22
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Influence of gamma radiation on microshear bond strength and nanoleakage of nanofilled restoratives in Er, Cr:YSGG laser-prepared cavities
摘要： Objective: To evaluate the effect of gamma radiation on microshear bond strength and nanoleakage of nanofilled restoratives in laser-prepared cavities. Materials and Methods: Twenty?eight flat buccal dentin surfaces were prepared for microshear bond strength test. Er, Cr:YSGG laser was used to prepare another 28 Class V cavities on the buccal surfaces of the molars. All teeth were divided into four groups; 1st group: Application of Filtek Z350 nanocomposite material, 2nd group: As the 1st group and then exposure to gamma radiation, 3rd group: Application of Ketac N100 nanoglass ionomer, and the 4th group: As the 3rd group and then gamma irradiated. The bond strength test was performed after storage in artificial saliva for 24 h. For the nanoleakage test, teeth were submerged in a solution of ammoniacal silver nitrate, sectioned, and then examined under a scanning electron microscope. The collected data were statistically analyzed. Results: Nanocomposite showed higher bond strength values than nanoglass ionomer. Despite the fact that gamma radiation did not decrease nanocomposite bond strength, it decreased nanoglass ionomer bond strength. Nanoglass ionomer-restored cavities showed higher silver ion penetration than nanocomposite in both control and gamma-irradiated groups. Conclusion: Gamma radiation has no effect on bond strength and nanoleakage of nanocomposite so that it can be placed before radiotherapy. On the other hand, the bond strength of nanoglass ionomer was adversely affected by gamma radiation.
关键词： nanoleakage,gamma radiation,Bond strength,Er, Cr:YSGG laser,nanocomposite,nanoglass ionomer
更新于2025-09-11 14:15:04
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Gamma ray enhanced Vis-NIR photoluminescence and cytotoxicity of biocompatible silica coated Nd3+ doped GdPO4 nanophosphors
摘要： Near infrared (NIR) emitting nanophosphors have a great potential for biomedical applications. Core nanoparticles of Nd3+ doped GdPO4@SiO2 with 3–6 nm sized spheres have been synthesized by solution combustion synthesis. The structure, morphology and luminescence properties of as synthesized nanophosphors have been examined by X-ray diffraction, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Photoluminescence spectra (PL). Upon photoexcitation at 532 nm, GdPO4:Nd3+@SiO2 emits red luminescence at 681 nm and NIR luminescence at 797 nm corresponding to 4F9/2 → 4I9/2 and 4F5/2 → 4I9/2 transitions, respectively. The luminescence intensity of nanophosphor had enhanced 2 folds on increasing the Nd3+ content from 1% to 5%. The luminescence intensity of these nanophosphors had further enhanced 2–3 folds and 8–10 folds after exposed to 150 kGy and 300 kGy of gamma radiation, respectively. In addition, this nanophosphor also exhibits high cytotoxicity against cell lines of PC-3 (Prostate cancer cells) and MCF-7 (Breast cancer cells).
关键词： Cytotoxicity,Gamma radiation,SiO2,Photoluminescence,Nanophosphors
更新于2025-09-10 09:29:36
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An Overview of the Synthesis of Gold Nanoparticles Using Radiation Technologies
摘要： At a nano-level, optical properties of gold are unique and gave birth to an emerging platform of nanogold-based systems for diverse applications, because gold nanoparticle properties are tunable as a function of size and shape. Within the available techniques for the synthesis of gold nanoparticles, the radiolytic synthesis allows proper control of the nucleation process without the need for reducing agents, in a single step, combined or not with simultaneous sterilization. This review details and summarizes the use of radiation technologies for the synthesis and preparation of gold nanoparticles concerning fundamental aspects, mechanism, current pathways for synthesis and radiation sources, as well as briefly outlines final applications and some toxicity aspects related to nanogold-based systems.
关键词： electron beam radiation,radiation technologies,X-ray,radiolytic synthesis,gamma radiation,gold nanoparticle
更新于2025-09-09 09:28:46
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Enhanced red luminescence by gamma irradiation on GdPO4:Er3+@SiO2 nanophosphor
摘要： The influence of gamma radiation on enhancement of red emission from Er3+ doped GdPO4@SiO2 nanophosphors was investigated. The luminescent emission was recorded after photoexcitation at 462 nm. The strong red luminescence at 690 nm corresponds to 4F9/2 → 4I15/2 transition. The luminescence intensity of the prepared phosphor had enhanced 2-4 folds and 4-6 fold after exposing to 150 kGy and 300 kGy gamma radiation, respectively. A linear response between luminescence intensity and irradiation dose was observed through PL dosimetry study. These biocompatible nanophosphors may have promising applications in biomedical and optoelectronic fields.
关键词： Nanophosphor,Gamma radiation,GdPO4,Erbium,Photoluminescence,SiO2
更新于2025-09-09 09:28:46
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Optical Passive Sensor Calibration for Satellite Remote Sensing and the Legacy of NOAA and NIST Cooperation
摘要： Post-irradiation stability of high-dose dosimeters has traditionally been an important measurement influence quantity. Though the exceptional stability of the alanine dosimeter response with time has rendered this factor a non-issue for routine work, the archival quality of the alanine dosimeter has not been characterized. Here the alanine pellet dosimeter response is measured up to seven years post-irradiation for a range of absorbed doses. This long-term study is accompanied by an examination of the environmental influence quantities (e.g., ambient light) on the relatively short-term (3-4 month) stability of both pellet and film commercial dosimeters. Both dosimeter types demonstrated exceptional stability in the short term and proved to be relatively insensitive to common influence quantities. The long-term data revealed a complex dose-dependent response trend.
关键词： dosimetry,electron paramagnetic resonance,gamma radiation,stability,alanine,time
更新于2025-09-04 15:30:14