Extra-light gamma-ray imager for safeguards and homeland security

Abstract

Gamma-ray imaging is the most important way to identify unknown gamma-ray emitting objects in decommissioning, the solving the security tasks, overcoming of accidents. Over the past two decades the systems for producing of gamma images in these conditions became more or less portable devices. However, in recent years, these systems have become converted into the hand-held devices. This is very important, especially in emergency situations, and measurements for safety reasons. We describe the first integrated handheld instrument for emergency and security applications. The device is based on the coded aperture image formation, position sensitive gamma-ray (X-ray) detector CdTe-Medipix2 (detectors produces by X-ray Imaging Europe) and tablet computer. The development was aimed at creating a very low weight system with high angular resolution. We present some sample gamma-ray images by camera. Main estimated parameters of the system are the following. The field of view video channel ∼ 490. The field of view gamma channel ∼ 300. The sensitivity of the system with a hexagonal mask for the source of Cs-137 (Eγ = 662 keV), is in units of dose D ∼ 30 μR. This option is less then order of magnitude worse than for the heavy, non-handheld systems (e.g., gamma-camera Cartogam, by Canberra.) The angular resolution of the gamma channel for the sources of Cs-137 is about 1.20.