Surface grafted scintillation sensors for selective detection of low level plutonium alpha activity

In the present study, thin film based extractive scintillation sensors with improved pulse height and detection limits have been developed. This has been achieved by surface grafting of phosphate based monomer, bis[2-(methacryloyloxy) ethyl] phosphate) (BMEP) on different polyether sulfone (PES) polymer substrates such as sheet and scintillating polymer inclusion membrane (SPIM). The pulse height and counting efficiency has been observed to improve with increase in the fluor component, 2,5-diphenyloxazole (PPO) in SPIM, whose counting efficiency becomes comparable to PPO containing polystyrene film at 50% fluor component. The phosphate modified substrates have been characterized for their surface morphology and functional groups. The contact angle of water with poly(BMEP) grafted SPIM and PES sheet was found less compared to substrates without grafting, showing the surface to be distinctively hydrophilic, thereby confirming successful grafting of BMEP layer on PES sheet and SPIM. The substrates have been found to selectively extract Pu in presence of similar activity of 241Am from 2 molL-1 HNO3 and have been tested upto Pu activity level as low as 118 mBq. The polymeric substrates developed in present study are simple to use and can be easily deployed for field applications with remote monitoring for low level detection of Pu.