Luminescence Imaging of Water During Irradiation of Beta Particles With Energy Lower Than Cerenkov-Light Threshold

Abstract

The luminescence imaging of water during irradiation of beta particles with energy lower than the Cerenkov-light threshold has widely been considered impossible because such particles do not emit Cerenkov light. Contrary to this consensus, we found that luminescence imaging of water is in fact possible with such relatively low-energy beta particles. Beta particles from a 500-kBq 45Ca beta source (maximum energy: 257 keV) were irradiated to pure water, and the source’s luminescence images were acquired with a high-sensitivity, cooled charge-coupled device camera. We also conducted image acquisition for an acrylic plate and a plastic scintillator. The water’s luminescence image during beta particle irradiation became visualized after a 1200-s acquisition time. The luminescence intensity with the beta irradiation of water was 0.54 photons/MeV, and the luminescence intensity with that of the acrylic plate was 3.3 photons/MeV. Consequently, we have shown that luminescence imaging of water using beta particles with energy lower than the Cerenkov-light threshold is a promising new method for beta particle detection and distribution measurements.