An optical element is provided. The optical element may comprise a material, the material being a matrix and a set of particles included in the matrix, the material having a molar fraction of SiO.sub.2 higher than or equal to 65 percent, each particle having a dimension smaller than or equal to 80 nanometers.

Provided is a glass for radiation detection having high fluorescence detection sensitivity and high weather resistance. A glass for radiation detection, comprising, in mol %, 0.1 to 30% of SiO.sub.2+B.sub.2O.sub.3, 0 to 20% of SiO.sub.2, 0 to 10% of B.sub.2O.sub.3, 40 to 70% of P.sub.2O.sub.5, 10 to 30% of Al.sub.2O.sub.3, 10 to 30% of Na.sub.2O, and 0.01 to 2% of Ag.sub.2O.

Provided is a glass for radiation detection having high fluorescence detection sensitivity and high weather resistance. A glass for radiation detection, comprising, in mol %, 0.1 to 30% of SiO.sub.2+B.sub.2O.sub.3, 0 to 20% of SiO.sub.2, 0 to 10% of B.sub.2O.sub.3, 40 to 70% of P.sub.2O.sub.5, 10 to 30% of Al.sub.2O.sub.3, 10 to 30% of Na.sub.2O, and 0.01 to 2% of Ag.sub.2O.