Infrared scintillation in gases, liquids and crystals

We report about experimental evidences of infrared scintillation in gaseous, liquid and crystal samples. We firstly studied noble gases at room temperature and near atmospheric pressure in the wavelength range between 0.7 and 1.81 /spl mu/m. Ar gas emits infrared photons when irradiated by a proton beam. Ionization electrons also induce such emission when they drift in the medium. The spectrum shows sharp lines corresponding to transitions between atomic excited states. Also Xe gas scintillates in the infrared region with a quantum yield higher than 2/spl middot/10/sup 4/ photons/MeV. Protons induce infrared scintillation in liquid Ar and liquid Xe too. We irradiated many inorganic crystals and studied their infrared emission between 1 and 15 /spl mu/m. Some samples present significant infrared scintillation. Among them CsI(Tl) has the highest yield ((4.9/spl plusmn/0.3)/spl middot/10/sup 3/ photons/MeV restricted to 0.7+1.8 /spl mu/m). The spectrum shows a broad line centered around 1.55 /spl mu/m.