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Sasaki, Miyuki; Sanada, Yukihisa; Torii, Tatsuo*; Yoshino, Masano*; Yoshikawa, Akira*
no journal, ,
The purpose of this study is to develop an inexpensive and simple omni-directional radiation imaging system using a fractal-shaped detector. This detector has sensitivity in all directions by arranging tetrahedral detectors of about 1 cm to 2 cm in fractal shape, and can identify the direction of radiation based on the difference in sensitivity. Previous studies shown that inverse problem analysis can better reproduce the distribution of radiation sources using the radiation count rates. For the design of this system, we propose a new analysis method when added the directional characteristics of radiation in addition to the count rates. This computational evaluation method was applied to an actual prototype detector system, and the sensitivity to actual radiation was compared with the calculated results to clarify the validity of the method.
Sasaki, Miyuki; Sanada, Yukihisa; Torii, Tatsuo*
no journal, ,
The FRIE detector has equal sensitivity to incoming radiation from all directions and identify the direction of incoming radiation based on the difference in response characteristics of individual detectors. An inverse problem analysis algorithm was constructed to simulate radiation incident from multiple directions and reconstruct an image, assuming actual imaging. The inverse problem algorithm is based on Map-EM, and the algorithm incorporates direction vectors from the sensitivity difference of each detector to achieve high accuracy. A new beta and gamma-ray radiation imaging system has been developed. In this presentation, as the second in the series of presentations, we report on the reconstruction method for gamma-ray imaging based on detector data.
Torii, Tatsuo*; Sugita, Takeshi*; Sasaki, Miyuki; Sanada, Yukihisa
no journal, ,
Using a prototype FRIE detector system constructed with 16 tetrahedral GAGG detectors with 12 mm on each side, we obtained measured data of radiation distribution around a hot spot in an environment with a surface dose rate of 10 micro Sv/h or higher. Two conditions were applied for the evaluation of image reconstruction: a fixed measurement condition at about 1 m from the hot spot and a rotational measurement condition at about 1 m from the hot spot, and the accuracy of the radiation images was compared. In this presentation, as the first of the series of presentations, we report the results obtained from the field measurements in the environment around the TEPCO's Fukushima Daiichi Nuclear Power Station by the prototype FRIE detector system.
Torii, Tatsuo*; Abe, Yuki*; Sasaki, Miyuki; Sanada, Yukihisa
no journal, ,
We are developing a radiation detector in the Sierpinski's tetrahedron shape, which is a fractal shape of self-similarity. The tetrahedral radiation sensor is a unit of 16 GAGG scintillators arranged in a Sierpinski tetrahedron shape and filled with heavy metal between the sensors. Although the total count rates of the 16 scintillators are almost the same for the incident direction, the count rates of the individual scintillators can be used to identify the incident direction of the radiation. In this presentation, we will report the results of the characteristic test and field measurement of the newly developed instrument based on the previous presentation at the AESJ conference.