  In recent years, demand for scintillation detectors with high time resolution
(better than 100 ps) has emerged in high-energy physics and medical imaging
applications. In particular, time of flight positron emission tomography
(TOF-PET) can greatly benefit from increasing time resolution of scintillators,
which leads to the increase of signal-to-noise ratio, decrease of patient dose,
and achievement of the superior spatial resolution of PET images. Currently,
extensive research of various types of materials is carried out to achieve the
best time resolution. In this review, the recent progress of various approaches
is summarized and scintillation compounds with the best temporal
characteristics are first reviewed. The review presents the physical processes
causing fast luminescence in inorganic and organic materials. Special attention
is paid to nanocomposites which belong to a new perspective class of
scintillating materials, consisting of a plastic matrix, inorganic
nanocrystalline fillers, and organic or inorganic luminescence activators and
shifters. The main features and functions of all parts of existing and
prospective nanocomposite scintillators are also discussed. A number of
currently created and investigated nanocomposite materials with various
compounds and structures are reviewed.
