Speaker
Description
One of the main challenges in the development of detectors for future collider
experiments is finding materials that can operate in high radiation environments
while maintaining their physical, chemical, and optical properties.
In this framework, scintillating materials and Cherenkov radiators, such as crystals
and glasses, represent a powerful tool for the design of large area radiation
detectors. In particular glasses are produced by using a relatively cheap melting
process (with respect to crystal growth) which makes them attractive candidates for
the instrumentation of large volumes as in the case of many High Energy Physics
(HEP) experiments.
A set of heavy glasses of 1 cm³ with density of ~4.1 g/cm³ and different chemical
compositions was produced by AFO Research Inc. and characterized at CERN. These
glasses (FP2035) are multicomponent alkali free fluorophosphate glasses, based on
Ba(PO3)2 -Al(PO3)3 - BaF2- MgF2 and doped and co-doped respectively with Pb and Ce
oxides and fluorides [1]. Undoped glass samples have also been studied for
comparison with doped ones.
The scintillation properties and timing performance of the samples have been
investigated through laboratory measurements and irradiation studies have also
been conducted to assess the effect of ionizing radiation on the optical properties of
the samples.
The Ce-doped samples show an emission of light peaking around 370 nm, a decay
time of about 40 ns and a light yield ranging from 100 to 600 ph/MeV, depending on
the Ce-concentration. Measurements of coincidence time resolution were also
performed using high energy pions and value of σt<35 ps were obtained with both
doped and undoped samples read-out with SiPMs.
The irradiation campaign showed that Ce doped FP2035 glasses have a better
radiation resistance, with respect to undoped and Pb-doped glasses, and maintain a
better transparency after exposure to 1000 Gy of gamma-rays from a Co-60 source.
A loss of transparency was noticed in the UV part of the spectrum in FP2035 Ce
doped glasses between 360-450 nm, overlapping with the scintillation emission
peak, and thus responsible for a decrease of light output after irradiation.
Hence, further optimization of the chemical composition of these glasses is required
to allow their use as radiation resistant scintillators in radiation environments with
Topic: Defects and Radiation Damage
ionizing doses above 1000 Gy. At the present time, these glasses may have a wide
range of applications as radiation hard lenses, windows or optical fibers for light in
the visible spectrum (above 450 nm) where the transparency is not degraded by
radiation.
References
[1] A.A. Margaryan. Ligands and Modifiers in Vitreous Materials, Spectroscopy of
Condensed Systems (World Scientific Press, Singapore, New Jersey, London, Hong
Kong, 1999).
