NEWSDetecting radioactivity in the environment: new sensors, new opportunities

24 June 2021

Ever since the discovery of radioactivity by Henri Becquerel in the late 19th century, understanding radioactivity has relied heavily on the use of new technology for its detection and measurement. Studying the properties of radioactivity over the years revealed an elusive subatomic world escaping our human senses and laying the foundation to formulate quantum mechanics.

The choice of radioactive detectors to study radioactivity is strongly connected to the existing technology providing state-of-the-art sensing materials which will in turn be able to offer better resolution and detection efficiency for a given problem at hand. Starting with simple Geiger-Mueller tubes, γ radiation can be detected in a rather straightforward way. However, spectroscopy requires a little more than plain detection and for several decades after WWII, the gold standard that led to numerous discoveries in nuclear physics was the use of scintillating crystals, mainly NaI(Tl) crystals of various sizes that provide good detection efficiency and ease of use.

The advent of semiconductor technology has given the opportunity to improve on the resolution researchers could have in registering γ radiation by relying on Ge crystals. Despite somewhat worse in detection efficiency (~20-25% relatively to 3″x3″ NaI(Tl) crystals), Germanium-based detectors had a vast impact on spectroscopy providing an excellent tool to spectroscopists, despite they are hungry for liquid nitrogen to operate (Ge semiconductive properties switch on at about 80 K, or -193°C).

Contemporary and future applications of radiation detection, such as the ones RAMONES will bring along, require another leap forward in sensing materials. Detecting radioactivity in the marine environment requires detectors that will feature the best characteristics from all worlds. RAMONES are already exploring the use of room-temperature semiconductive materials, such as CdZnTe (CZT in short) that are portable, lightweight, low-power, efficient like NaI and of high resolution as high-purity Ge (HPGe) detectors. Our first simulations show very promising results as to what we could expect when RAMONES has completed all tasks and meet the objective goals in the project timeline.

Below is a sample comparison of three crystals of different sizes, prepared by the NKUA team (T.J. Mertzimekis, G. Siltzovalis, V. Lagaki, I. Madesis, P. Vasileiou). The prospects are in favor. RAMONES is ready to move the sensing technology in the marine environment beyond the state of the art!