Kerst Thomas, Malmbeck Rikard, Lal Banik Nidhu, Toivonen Juha
Photonics Laboratory, Physics Unit, Tampere University, P.O. Box 692, 33101 Tampere, Finland.
Helsinki Institute of Physics, Helsinki University, P.O. Box 64, 00014 Helsinki, Finland.
Sensors (Basel). 2019 Apr 2;19(7):1602. doi: 10.3390/s19071602.
When exposed to air, alpha particles cause the production of light by exciting the molecules surrounding them. This light, the radioluminescence, is indicative of the presence of alpha radiation, thus allowing for the optical sensing of alpha radiation from distances larger than the few centimeters an alpha particle can travel in air. While the mechanics of radioluminescence in air and other gas compositions is relatively well understood, the same cannot be said about the radioluminescence properties of liquids. Better understanding of the radioluminescence properties of liquids is essential to design methods for the detection of radioactively contaminated liquids by optical means. In this article, we provide radioluminescence images of Am-241 dissolved in aqueous nitric acid ( HNO 3 ) solution and present the recorded radioluminescence spectrum with a maximum between 350 nm and 400 nm , and a steep decrease at the short wavelength side of the maximum. The shape of the spectrum resembles a luminescence process rather than Cerenkov light, bremsstrahlung, or other mechanisms with broadband emission. We show that the amount of light produced is about 150 times smaller compared to that of the same amount of Am-241 in air. The light production in the liquid is evenly distributed throughout the sample volume with a slight increase on the surface of the liquid. The radioluminescence intensity is shown to scale linearly with the Am-241 concentration and not be affected by the HNO 3 concentration.
当暴露于空气中时，α粒子通过激发其周围的分子而产生光。这种光，即放射性发光，表明存在α辐射，从而能够从大于α粒子在空气中所能行进的几厘米的距离对α辐射进行光学传感。虽然空气中以及其他气体成分中的放射性发光机制相对已被充分理解，但对于液体的放射性发光特性却并非如此。更好地了解液体的放射性发光特性对于设计通过光学手段检测放射性污染液体的方法至关重要。在本文中，我们提供了溶解在硝酸（HNO₃）水溶液中的镅 - 241的放射性发光图像，并展示了记录的放射性发光光谱，其最大值在350纳米至400纳米之间，且在最大值的短波长侧急剧下降。该光谱的形状类似于发光过程，而不是切伦科夫光、韧致辐射或其他具有宽带发射的机制。我们表明，与相同量的镅 - 241在空气中产生的光相比，液体中产生的光量约小150倍。液体中的光产生在整个样品体积中均匀分布，在液体表面略有增加。结果表明，放射性发光强度与镅 - 241浓度呈线性比例关系，且不受硝酸浓度的影响。
