A performance study of an electron-tracking Compton camera with a compact system for environmental gamma-ray observation

Abstract

An electron-tracking Compton camera (ETCC) is a detector that can determine the arrival direction and energy of incident sub-MeV/MeV gamma-ray events on an event-by-event basis. It is a hybrid detector consisting of a gaseous time projection chamber (TPC), that is the Compton-scattering target and the tracker of recoil electrons, and a position-sensitive scintillation camera that absorbs of the scattered gamma rays, to measure gamma rays in the environment from contaminated soil. To measure of environmental gamma rays from soil contaminated with radioactive cesium (Cs), we developed a portable battery-powered ETCC system with a compact readout circuit and data-acquisition system for the SMILE-II experiment. We checked the gamma-ray imaging ability and ETCC performance in the laboratory by using several gamma-ray point sources. The performance test indicates that the field of view (FoV) of the detector is about 1sr and that the detection efficiency and angular resolution for 662keV gamma rays from the center of the FoV is $(9.31\pm 0.95)\times 10^{{}^{-}5}$ and $5.9^{\circ }\pm 0.6^{\circ }$, respectively. Furthermore, the ETCC can detect 0.15$\mu Sv/h$ from a ${}^{137}$Cs gamma-ray source with a significance of 5$\sigma$ in 13 min in the laboratory. In this paper, we report the specifications of the ETCC and the results of the performance tests. Furthermore, we discuss its potential use for environmental gamma-ray measurements.

arXiv comment10 pages, 7 figures, proceeding of the 10th International Conference on Position Sensitive Detectors (PSD10)

References in corpus (5)

• Observation of Diffuse Cosmic and Atmospheric Gamma Rays at Balloon Altitudes with an Electron-tracking Compton Camera
• Performance of the TPC with Micro Pixel Chamber Readout: micro-TPC
• Development of an ASD IC for the Micro Pixel Chamber
• Development of a 30 cm-cube Electron-Tracking Compton Camera for the SMILE-II Experiment
• Performance of a new electron-tracking Compton camera under intense radiations from a water target irradiated with a proton beam

Cited by in corpus (3)

• Establishment of Imaging Spectroscopy of Nuclear Gamma-Rays based on Geometrical Optics
• First On-Site True Gamma-Ray Imaging-Spectroscopy of Contamination near Fukushima Plant
• Quantitative imaging of 478-keV prompt gamma rays from boron neutron capture reactions