Low-Background Shielding Box for Autoradiography of Environmental Samples and the α-, β-, and γ-ray Sensitivities of the Imaging Plates

Abstract

Autoradiography using imaging plates is a conventional method for the visualization of the distribution of radionuclides. Imaging plates have high sensitivity to the charged particles of α- and β-rays but are also sensitive to γ-rays. When the radioactivity level in the sample is low, a longer exposure time is needed, and shielding of the natural background radiation is necessary. Large imaging plates (e.g., 35 × 40 cm), which can obtain the radioactivity distribution over a wider area, were developed. In this work, a low-background shielding box is developed for large imaging plates, and the shielding characteristics of the box and sensitivities of the imaging plate to α-, β-, and γ-rays are quantitatively investigated. It is shown, by considering the sensitivity of imaging plates to α-, β-, and γ-rays, that most images of environmental samples are the result of α- or β-rays emitted from radionuclides at the sample surface, but not from the whole sample. To exemplify autoradiography using the presented shielding box, some environmental samples contaminated with radioactive fallout from the Fukushima Daiichi Nuclear Power Plant accident are measured. The distribution of radionuclides is clearly visualized and, furthermore, information of the migration of radiocesium in the sample is obtained.

Calibration of imaging plates sensitivity to high energy photons and ions for laser-plasma interaction sources

“…As of today, the employment of radiation diagnostics is one of the biggest challenges faced during the experimental campaigns, which are used to measure plasma characteristics by recording the outgoing emissions. Passive instruments such as radiochromic film (RCF), CR39 and LR-115, while serving an specific purpose, are among the popular tools capable of measuring energy spectra and spatial distribution of emitted ions [9][10][11][12][13], high energy neutron [14,15], epithermal and thermal neutrons [16,17], high energy electrons [18,19], x-rays and gamma radiation [20][21][22]. Yet, apart from the above diagnostics, imaging plates (IP) are remaining between the most commonly used, because of their sensitivity to all types of radiations with a high dynamic range (>10 5 ), while being insensitive to strong electromagnetic pulses created by laser-plasma interactions [23].…”