1. Department of Physics, Wake Forest University, Winston-Salem, North Carolina 27106, USA
2. National Centre for Nuclear Research, Otwock-Swierk, Poland
3. ScintiTech Inc., Shirley, Massachusetts 01464, USA
4. Istituto Nazionale di Fisica Nucleare, Sezione di Padova, Padova, Italy
5. Institute for Scintillation Materials of the NAS of Ukraine, Kharkov, Ukraine