No-waste-measurement method with a LSC. Effects of surface treatment for plastic scintillator

Plastic scintillator (PS) sheets were treated with dielectric barrier discharge plasma (DBD) or by fluorine gas (F-gas) to become its surface hydrophilicity. A hydrophobic PS-sheet changed by these treatments and contact area of sample solution became wide, so measurement efficiency of beta-rays became higher than before treatment. Surface treatment was effective, especially for low energy beta-rays. Average measurement efficiency was approx. 35% for 5 μL tritium samples with 1 min. plasma treatment, and count rate showed good linearity with activity (Bq) from 2 to 400 Bq/5 μL. Little radioactive waste was generated by the PS-sheets method because the PS-sheets were measured by a conventional liquid scintillation counter (LSC) without liquid scintillator and they were possible to reuse by simple rinsing. Also unquenching spectra was gotten by the PS-sheets. The PS-sheets method is possible both of qualitative and quantitative analysis without radioactive wastes. (author)