Speaker
Description
Industrial Scale R&D of Fast Scintillators
Silvia Sykorová1, Martin Nikl2, Jindřich Houžvička1
1) CRYTUR, spol. s r.o., Palackého 175, 511 01 Turnov, Czech Republic,, www.crytur.com
2) Institute of Physics, Academy of Sciences, Na Slovance, 180 00 Praha, www.fzu.cz
Large infrastructure projects e.g. in CERN or FAIR require typically large volume scintillators of the unique technical parameters, but manufactured with affordable cost and production capacity corresponding to the size of the detector and available time frame. Example of such scintillator development can be documented on the recent re-start of the PWO production, as well as on the new development for the considered calorimeter up-grades in CERN using the modified FastYAG crystals.
The new patented crystal growth method (CRIG - CRystal Improved Growth) was developed to grow large, core-free garnet crystals (YAG, LuAG, etc) recently. The maximum diameter reached so far is 140mm, and the maximum crystal weight is up to 12 kg. Crystals of unmatched quality are produced using this method – with their unique size, homogeneity and the low material stress.
Garnet materials (especially YAG:Ce) show excellent radiation hardness. Hence, they can be used, for example, even for very large multipixel detectors in very strong radiation fields. Around 8.000 fibres, 1x1x200mm can principally be made out from one such a big size crystal, thus meeting the requirements both from the perspective of the cost and manufacturing capacity. Fibre optical parameters still remain very impressive, significantly better than those of fibres produced by micro-pulling down technology so far reported.
Size of the mentioned crystals and their homogeneity matter also for many other applications. YAG:Ce crystal is frequently used as a screen for imaging of various objects. Enlarged size of the screen brings obvious advantages. The screens can be made in such a quality that submicron resolution can be achieved when inspecting various material, even those with low Z-contrast like living tissues or carbon fibre/carbon resin composites.
The key scintillation parameters like light yield and decay time can be modified to meet the parameters specific and critical in certain detectors. Example of the new FastYAG crystal, doped with cerium, will be shown. Decay time of this material was tuned down to 40 ns only, and afterglow minimized as well, to reduce pile up in the considered up-grade of HL-LHC calorimeter. Still, the crystal can be made of such size, that its application seems to be the competitive solution also from the cost point of view.
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