• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.1
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• pp.225-232
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• 2014

Optical parametric amplification has been analyzed for the Cerenkov-idler configuration in planar waveguides. The coupled-mode theory is employed for the analysis. The coupled-mode equations are derived and the approximate analytic solution is obtained for no pump depletion. From the analytic solution, it is shown that the signal power gain can be enhanced as the Cerenkov radiation angle of the idler approaches to zero. The numerical example is also shown for the effect of the Cerenkov radiation angle approaching zero.

• Journal of Sensor Science and Technology
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• v.23 no.4
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• pp.245-250
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• 2014

When the charged particle travels in transparent medium with a velocity greater than that of light in the same medium, the electromagnetic field close to the particle polarizes the medium along its path, and then the electrons in the atoms follow the waveform of the pulse which is called as Cerenkov light or radiation. This type of radiation can be easily observed in a spent fuel storage pit. In optical fibers, the Cerenkov light also can be generated due to their dielectric components. Accordingly, the radiation-induced light signals can be obtained using optical fibers without any scintillating material. In this study, to measure the intensities of Cerenkov radiation induced by gamma-rays, we have fabricated the fiber-optic Cerenkov radiation sensor system using silica optical fibers, plastic optical fibers, multi-anode photomultiplier tubes, simulated spent fuel assembly and a scanning system. To characterize the Cerenkov radiation generated in optical fibers, the intensities of Cerenkov radiation generated in the silica and plastic optical fibers were measured. Also, we measured the longitudinal distribution of gamma rays emitted from the Ir-192 isotope by using the fiber-optic Cerenkov radiation sensor system and simulated spent fuel assembly.

• Korean Journal of Optics and Photonics
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• v.25 no.1
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• pp.44-49
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• 2014

We have analyzed the amplification of a signal wave in the optical parametric interactions of the pump, signal, and idler waves in planar waveguides, with the pump wave being Cerenkov radiation. Based on the coupled-mode theory, we have derived the first-order coupled-mode differential equations for no pump depletion. The equations can easily be solved numerically. The approximate analytical and numerical solutions of the equations show that the signal wave can be amplified parametrically.

• Journal of Sensor Science and Technology
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• v.15 no.3
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• pp.186-191
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• 2006

In general, Cerenkov light is produced by a charged particle that passes through a medium with a velocity greater than that of visible light. Although the wavelength of Cerenkov light is very broad, the peak is in the almost visible range from 400 to 480 nm. Therefore, it always causes a problem to detect a real light signal that is generated in the scintillator on the fiber-optic sensor tip for dose measurements of high-energy electron beam. The objectives of this study are to measure, characterize and remove Cerenkov light generated in a fiber-optic radiation sensor tip to detect a real light signal from the scintillator. In this study, the intensity of Cerenkov light is measured and characterized as a function of incident angle of electron beam from a LINAC, and as a function of the energy of electron beam. As a measuring device, a photodiode-amplifier system is used, and a subtraction method using a background optical fiber is investigated to remove Cerenkov light.

• Korean Journal of Optics and Photonics
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• v.17 no.4
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• pp.312-316
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• 2006

In this study, a miniature fiber-optic radiation sensor has been developed using a water-equivalent organic scintillator for electron beam therapy dosimetry. The intensity of Cerenkov light is measured and characterized as a function of the incident angle of the electron beam from a LINAC. Also, a subtraction method using a background optical fiber without a scintillator and an optical discrimination method using optical filters are investigated to remove Cerenkov light, which could cause problems or limit the accuracy for detecting a fluorescent light signal in a fiber-optic radiation sensor.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2006.08a
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• pp.73-73
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• 2006

• Journal of Sensor Science and Technology
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• v.17 no.2
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• pp.100-105
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• 2008

The objectives of this study are to measure and to remove Cerenkov lights generated in a fiber-optic radiation sensor by a charge-coupled device. we have fabricated a fiber-optic radiation sensor which comprises an organic scintillator, a plastic optical fiber and a charge-coupled device. Charge-coupled device as a light measuring tool has many advantages which are easy in multi-dimensional measurements, high spatial resolution and relatively low cost.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.272-274
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• 2002

The contribution of light in high-energy film dosimetry was examined using six commercially available solid water substitute phantoms. As six commercially available phantoms; RMI-451, Mix-DP, WE211, WE211-Black, PMMA and PMMA Black were evaluated in this study. It is difficult to evaluate the contribution of Cerenkov radiation and the optical permeability to the relative and/or absolute dosimetry using unpacked film in these phantoms. Therefore the contribution of Cerenkov radiation was estimated by the comparison between film densities in the shielded side (shutting off the light) and unshielded sides on a phantom. The effect of optical permeability was measured under ambient light by the time scale method. The results suggest that the use of black colored phantoms may improve the accuracy of dose measurement in film dosimetry.

• Analytical Science and Technology
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• v.15 no.1
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• pp.20-25
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• 2002

An accurate and simple analytical technique for $^{89}Sr$ and $^{90}Sr$, overcoming the demerits of the conventional method, has been developed with extraction chromatography and liquid scintillation counting. The Sr fraction was separated from hindrance elements with oxalate coprecipitation or cation exchange resin and purified with Sr-Spec column. With liquid scintillation counter, $^{89}Sr$ was measured by Cerenkov radiation method, and $^{90}Sr$ was measured by spectrum unfolding method. The developed radioactive strontium separation method was validated by application to the IAEA-reference material (IAEA-375, Soil) and radioactive waste samples.

• Journal of Biomedical Engineering Research
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• v.27 no.6
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• pp.332-336
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• 2006

In this study, we have fabricated a fiber-optic radiation sensor using an organic scintillator for high energy electron beam therapy. The intensities of scintillating light from a fiber-optic radiation sensor are measured with different field size, electron beam energy and monitor unit of a clinical linear accelerator. To obtain percent depth dose(PDD), the amount of scintillating light is measured at different depth of polymethylmethacrylate(PMMA) phantom. Also the intensity of Cerenkov light is measured and characterized as a function of incident angle of electron beam and a subtraction method is investigated using a background optical fiber to remove a Cerenkov light.