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Wyszukujesz frazę "Pereira, T. M." wg kryterium: Autor


Wyświetlanie 1-2 z 2
Tytuł:
Development of crystals based on cesium iodide for measurements of gamma radiation and alpha particles
Autorzy:
Pereira, M. C. C.
Filho, T. M.
Hamada, M. M.
Powiązania:
https://bibliotekanauki.pl/articles/148098.pdf
Data publikacji:
2009
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
scintillator
crystals
gamma radiation
alpha particles
luminescence
Opis:
During the past 50 years, scintillators have been among the most important nuclear radiation detectors. Inorganic scintillators are widely used in experimental nuclear physics, high energy physics, nuclear medicine, nuclear tomography, environmental studies and many other fields of use. Scintillation crystals based on cesium iodide (CsI) are matters of relatively low hygroscopy, high atomic number, easy handling and low cost, characteristics that favor their use as radiation detectors. In this work, the growth of pure CsI crystals, CsI:Br and CsI:Pb, using the Bridgman technique, is described. Ions of divalent lead (Pb2+) doped in the crystal structures are efficient emission centers and their application as scintillators is still the reason for intensive studies. Recently, promising results have been found for crystals of CsI doped by bromine (Br) for their use as radiation detectors. The concentration of the bromine doping element (Br) was studied in the range from 1.5 × 10–1 M to 10–2 M and the lead (Pb) in the range from 10–2 M to 5 × 10–4 M. To evaluate the scintillators developed, systematic measurements were carried out for luminescence emission and luminescence decay time for gamma radiation, Vickers microhardness assays, and analysis of crystals response to the gamma radiation, in the energy range from 350 keV to 1330 keV, and alpha particles from a 241Am source, with energy of 5.54 MeV. The obtained values for luminescence decay time for CsI:Br and CsI:Pb crystals, were from 13 to 19 ns.
Źródło:
Nukleonika; 2009, 54, 3; 151-155
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gamma-ray computed tomography SCANNERS for applications in multiphase system COLUMNs
Autorzy:
Calvo, W. A. P.
Hamada, M. M.
Sprenger, F. E.
Vasquez, P. A. S.
Rela, P. R.
Martins, J. F. T.
de Matos Pereira, J. C. S.
Omi, N.
de Mesquita, C. H.
Powiązania:
https://bibliotekanauki.pl/articles/148082.pdf
Data publikacji:
2009
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
industrial computed tomography
multiphase flow systems
non-destructive testing
gas absorption column
industrial process optimization
packed distillation columns
scanning systems
Opis:
Gamma-ray tomography experiments have been carried out to detect spatial patterns in the porosity, in a 0.27 m diameter packed steel column using a first generation computed tomography (CT) system. The CT scanner consists of a NaI(Tl) detector 5.08 cm in diameter, and an encapsulated 137Cs (3.7 GBq) radioactive source, located opposite to the center of the detector. The detector and the source, mounted on a fixed support and the column, can rotated and dislocate by two stepping motors controlled through a microprocessor. Different sizes of stainless steel Raschig rings (12.6, 37.9 and 76 mm) have been examined. The primary objective of this work is to detect spatial patterns and statistical information on porosity variation in packed distillation columns. Horizontal scans, at different vertical positions of the packed bed were made for each size of Raschig rings. Radial porosity variation within the packed bed has been determined. This study has demonstrated that the porosity and its spatial distribution in a metallic packed column can be measured with adequate spatial resolution using the gamma-ray tomography technique. After validation of this first generation CT, the turntable design to rotate and dislocate the 60Co or 137Cs sealed gamma-ray sources and multidetector array for the third generation industrial computed tomography was also developed.
Źródło:
Nukleonika; 2009, 54, 2; 129-133
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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