solidiscounts.blogg.se - Physical processes in inorganic scintillators

#PHYSICAL PROCESSES IN INORGANIC SCINTILLATORS SERIES#

We show that these colour-tunable perovskite nanocrystal scintillators can provide a convenient visualization tool for X-ray radiography, as the associated image can be directly recorded by standard digital cameras. These features allow the fabrication of flexible and highly sensitive X-ray detectors with a detection limit of 13 nanograys per second, which is about 400 times lower than typical medical imaging doses. Unlike bulk inorganic scintillators, these perovskite nanomaterials are solution-processable at a relatively low temperature and can generate X-ray-induced emissions that are easily tunable across the visible spectrum by tailoring the anionic component of colloidal precursors during their synthesis. These nanocrystal scintillators exhibit strong X-ray absorption and intense radioluminescence at visible wavelengths.

#PHYSICAL PROCESSES IN INORGANIC SCINTILLATORS SERIES#

Here we describe experimental investigations of a series of all-inorganic perovskite nanocrystals comprising caesium and lead atoms and their response to X-ray irradiation. However, conventional scintillators are generally synthesized by crystallization at a high temperature and their radioluminescence is difficult to tune across the visible spectrum.

The ability of a scintillator to absorb high-energy (kiloelectronvolt-scale) X-ray photons and convert the absorbed energy into low-energy visible photons is critical for applications in radiation exposure monitoring, security inspection, X-ray astronomy and medical radiography4,5. Try to utilize DSO as much as possible in crystal tests.Abstract: The rising demand for radiation detection materials in many applications has led to extensive research on scintillators1–3.Decay time measurement with digital oscilloscope(DSO).Generally Teflon is the best reflector.Wrapping is important : tyvek, aluminized foil, teflon.Chochralski : melted and uplifted as rotating.Most inorganic scintillators are imported.If this x-ray escape from the detector, Emeasured=Egamma-Ex-ray Q3 : Can you see the escape peak with Cs-137 source(662 keV) ?.X-ray excape peak : when photoelectric absorption usually from K-shell electrons.For Cherenkov detector, the Quartz(fused silica) window preferable Įxample of intermediate size scintillator spectrum with 2 different energy gamma source Q : can you think over the origin of each peaks ?.Typically Photomultiplier 3 currents flows thru PMT Photons from scintillator are measured photosensor.

Produced lights(photons) should be collected efficiently L : attenuation length n : refractive index.

Light output light output of inorganic scintillator grows as doping concentration but it saturates.

Temperature dependence of inorganic scintillator Generally light output increases for non-doped scintillator as temperature decreases

Emission spectra is more “red”, so overlap is small.

Capture by lattice luminescence center Įmission spectra of inorganic scintillator Pure crystal : large overlap between absorption spectra and emission spectra Doped crystal : energy of luminescence center < excitation energy.

Thermal equilibrium (part of energy go to phonons).

excitation energy transferred to luminescence center.

Independent diffusion  Exciton diffuse in the lattice and.

Rodnyi Particle excite a valence band electron to produce electron and hole Scintillation mechanism (very complex) Still no first principle solution : Refer to Birk’s & “ physical processes in inorganic scintillators”, P.A.

Exciton is “bound” state of electron and hole Pure crystal And Doped crystal.

Photons are produced by recombination of “exciton”.

The type of nuclei in crystal is important depending on physics. Scintillation Detectors Inorganic crystals are used for dark matter search, double beta decay, sattellite gamma measurements, accelerator calorimeters, and neutrino physics. Inorganic Scintillators Yeongduk Kim Sejong University 2004.