S.I.Vasetsky, A.S.Gershun, V.Yu.Gres`,
A.M.Kudin, T.A.Charkina, G.I.Yakhnis
Received March 6, 1998
The light yield and energy
resolution impairment of NaI(Tl) crystals being stored unsealed is associated
with changes in the scintillation efficiency, e
, and the light collection coefficient, t.
It is just the depletion of the crystal in activator that is responsible
for the e deterioration in the near-surface
"dead" scintillator layer while changes in t
are due to the surface enrichment in thallium, no matter what is the detector
size. A simple test is proposed to detect the initial stages of the crystal
moistening influenced on the NaI(Tl) crystal properties.