Speaker
Ms
Mika Kagaya
(Ibaraki University)
Description
We developed a Compton camera γI (Gamma Eye) using CsI (Tl) scintillators for measurement of arrival direction of gamma rays produced by radioactive cesium released into the environment from the Fukushima Dai-ichi Nuclear Power Plant accident due to the great east Japan earthquake and subsequent tsunamis in 2011.
The radiation exposure of residents remains extremely a serious problem in Japan. The capability of gamma-ray imaging with good angular resolution is a key feature for identification of radiation hotspots and effective decontamination operation. A detector using Compton kinematics is one of the best candidates. Some Compton cameras for such purpose are being developed so far.
However, they are not sufficient to cover a wide contamination area with the dose rate in air of < 1µSv/hour around the Fukushima Power Plant because of their low detection efficiency and/or very high cost. Thus we developed a novel Compton camera γI (Gamma Eye) with high sensitivity and low-cost. It consists of 2 arrays of detectors which act as a Compton scatterer and absorber. Energies deposited by Compton scattered electrons and subsequent photoelectric absorption measured by photomultipliers are used for image reconstruction. Each array consists of 8 large CsI (Tl) scintillator cubes, 3.5cm on a side, which are inexpensive and have good energy resolution. The 2 arrays are separated by 40cm to provide a 60-degree wide field of view as well as to keep position determination accuracy < 5 degree. The imaging capability was verified by test measurements in Fukushima Prefecture together with the laboratory tests.
Primary author
Ms
Mika Kagaya
(Ibaraki University)
Co-authors
Prof.
Hideaki Katagiri
(Ibaraki University)
Prof.
Hiroshi Muraishi
(Kitasato University)
Mr
Kazuhiro Sato
(Shinsei Corporation)
Mr
Kohei Nakayama
(Ibaraki University)
Mr
Masao Hosokawa
(Fuji Electric)
Prof.
Ryoji Enomoto
(Tokyo University (ICRR))
Mr
Ryuji Hanafusa
(Fuji Electric)
Prof.
Shohei Yanagita
(Ibaraki University)
Prof.
Tatsuo Yoshida
(Ibaraki University)
Prof.
Toru Takeda
(Kitasato University)
Mr
Yoshikazu Ito
(Fuji Electric)
