FoCalinspirace odjinud

Libor ŠkodaWorkshop EJČF 2013

Nanocomposite scintillators with polymer matrix

Scintillating materials- production problems (single crystals growth, preparation in ceramic form, …)

Composite materialsscintillating (nano)material incorporated inside the polymer matrix:• versatility• wide application field of the combined materials• easiness of preparation• various compounds as a matrix such as porous silica, polymethylmethacrylate, tetraethoxysilan, epoxy matrices etc.

KJCH FJFI:• nano-scale powder materials (nickel, zinc, yttrium, aluminum and cobalt oxides, zinc peroxide and hydroxide, yttrium and lutetium aluminum garnets and cobalt(II) aluminate)• precipitation from aqueous solution induced by accelerated electrons, gamma, UV radiation• interesting characteristics - high chemical purity, high specific surface area and narrow distribution of particle size

Zinc oxide:• wide direct band gap (~ 3.3 eV)• high exciton and biexciton energies (60 meV or 15 meV)• very short luminiscence lifetime under 1 ns• strong room temperature luminiscence• doping with various ions - affects both intesity and lifetime of the luminiscence

ZnO:Ga(La)/polymer nanocomposite:

• nanosized crystalline ZnO (gallium nitrate or lanthanum doped) powder (particle size ~ 100 nm) - very intensive excitonic luminescence under X-ray excitation (40 kV, 15 mA), with distinct maximum at ~ 395 nm• homogenous dispersion in the solution of urethane dimethacrylate monomers • fast UV-induced polymerization (-> optically transparent polyurethane matrix with embedded nanopowder)• most promising and interesting powders were compared to Bismuth Germanate (BGO)

Radioluminescence spectra of various ZnO:Ga(La) powders and powders incorporated into the polymer matrix

Conclusion:

• due to heat treatment and reduction in the reduction atmosphere:

- no emission in the visible region of the spectrum- no noise from unwanted impurities or defects

• maximum of the intensity of the luminescent peak - 392 nm• gallium doped sample shows significantly higher intensity of the luminescence• intensity of all of the nanocomposites is significantly lower than the appropriate powders• this nanocomposites show exciton luminescent but large amount of the photons is absorbed by the polymer

- připojení opt. vláken ke scintilátoru- efektivnější sběr signálu (?)

- jednodušší zpracování tvaru a povrchu

- přímé odlévání do formy na W-desce (?)

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