Standoff UV-C imaging of alpha particle emitters

Abstract

Alpha particles are proven to be very useful in many areas of medicine, technology and science. Yet, they represent the biggest risk to soft biological tissues compared to all nuclear decay products when ingested or inhaled, implying thus stringent radiation protection measures in the management and monitoring of samples that emit them. In this paper we present a standoff optical imaging approach that enables sensing of a radiological threat items at facilities where alpha-emitting material is manufactured, handled, used and stored, at safe distances without putting personnel at risk or contaminating equipment. The optical imaging of alpha-emitting samples is based on the radiation induced air luminescence (radioluminescence) in the UV-C (solar-blind) spectral region which enables detection of alpha particles even under bright light conditions. We show that by adding trace amounts of nitric oxide into the nitrogen atmosphere surrounding the sample, alpha sources with specific activities as low as 1.5 Bq/cm2 can be remotely imaged. This work provides a proof-of-concept implementation of a novel imaging approach that not only enhances capabilities of a state to take actions which effectively mitigate consequences of an radiological emergency for the society, health, environment and economy, but also benefits nuclear industry in decommissioning efforts.