Organic Glass Scintillator Characterization For Radioxenon Detection

The International Monitoring System utilizes four areas of detection for above and below ground explosions. Nuclear events can be confirmed through detection of radioxenon isotopes 131mXe, 133Xe, 133mXe, and 135Xe from atmospheric samples. Beta-gamma coincidence detection systems that utilize plastic scintillators for beta particle detection and sodium iodide for correlated gamma ray detection are used to identify these isotopes. However, the plastic scintillators used in these systems exhibit memory effects and poorer energy resolution compared to other materials. Past investigations for improvement include stilbene organic scintillators replacing the plastic. This approach showed a reduced memory effect, but comparable energy resolutions. Construction of the stilbene scintillators was found to be difficult due to its fragile material, as well. Now, organic glass scintillators are of interest because the glass is capable of pulse shape discrimination (PSD) and demonstrates similar, and in some case better, properties to stilbene. This material outperforms stilbene with a higher light output, better time resolution, and is easily machinable. Custom molds are used to cast the glass into desired shapes, and the material is more robust than stilbene. In this work, various geometries of the organic glass scintillators and the effects of added diffuse and specular reflectors were investigated with experiments and simulations. Corresponding results from PSD and energy spectra are presented for each geometry and compared to results through Geant4 models. These results will be used as groundwork in the development of an organic glass scintillator cell, which has potential to improve on the plastic scintillator cells seen in the field.