1. Department of Physics, Wake Forest University, Winston-Salem, North Carolina 27106, United States
2. Institute of Light and Matter, CNRS, Claude Bernard University Lyon 1, 69100 Villeurbanne, France
3. Institute for Scintillation Materials of the NAS of Ukraine, 61001 Kharkiv, Ukraine
4. Istituto Nazionale di Fisica Nucleare, Sezione
di Padova, 35131 Padova, Italy
5. Skobeltsyn Institute of Nuclear Physics, Moscow State University, 119991 Moscow, Russia