  The high energy physics community has recently identified an $e^+e^-$ Higgs
factory as one of the next-generation collider experiments, following the
completion of the High Luminosity LHC program at CERN.The moderate radiation
levels expected at such colliders compared to hadron colliders, enable the use
of less radiation tolerant but cheaper technologies for the construction of the
particle detectors. This opportunity has triggered a renewed interest in the
development of scintillating glasses for the instrumentation of large detector
volumes such as homogeneous calorimeters. While the performance of such
scintillators remains typically inferior in terms of light yield and radiation
tolerance compared to that of many scintillating crystals, substantial progress
has been made over the recent years. In this paper we discuss the time
resolution of cerium-doped Alkali Free Fluorophosphate scintillating glasses,
read-out with silicon photo-multipliers in detecting single charged tracks and
at different positions along the longitudinal development of an electromagnetic
shower, using respectively 150~GeV pions and 100~GeV electron beams at the CERN
SPS H2 beam line. A single sensor time resolution of 14.4~ps and 5-7~ps was
measured respectively in the two cases. With such a performance the present
technology has the potential to address an emerging requirement of future
detectors at collider experiments: measuring the time-of-flight of single
charged particles as well as that of neutral particles showering inside the
calorimeter and the time development of showers.
