Measurement of gamma quantum interaction point in plastic scintillator   with WLS strips
  We demonstrated the feasibility of measuring the axial coordinate of a gamma quantum interaction point in a plastic scintillator bar via the detection of scintillation photons escaping from the scintillator with an array of wavelength-shifting (WLS) strips. Using a test set-up comprising a BC-420 scintillator bar and an~array of sixteen BC-482A WLS strips we achieved a spatial resolution of~5\,mm~($\sigma$) for annihilation photons from a $^{22}$Na isotope. The studied method can be used to improve the spatial resolution of a plastic-scintillator-based PET scanner which is being developed by the J-PET collaboration. 
J. Smyrski, D. Alfs, T. Bednarski, P. Bia{\l}as, E. Czerwi\'nski, K.   Dulski, A. Gajos, B. G{\l}owacz, N. Gupta-Sharma, M. ...
physics.ins-det