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Local coordination state of rare earth in eutectic scintillators for neutron detector applications.

Masai H, Yanagida T, Mizoguchi T, Ina T, Miyazaki T, Kawaguti N, Fukuda K - Sci Rep (2015)

Bottom Line: In this work, we examine optical properties of Eu-doped 80LiF-20CaF2 eutectics for neutron detector applications based on the Eu distribution.However, transparency, which depends on an ordered lamellar structure, is found to be important for a high light yield in neutron detection.The results confirm the effectiveness of the basic idea concerning the separation of radiation absorbers and activators in particle radiation scintillation and present potential for further improvement of novel bulk detectors.

View Article: PubMed Central - PubMed

Affiliation: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.

ABSTRACT
Atomic distribution in phosphors for neutron detection has not been fully elucidated, although their ionization efficiency is strongly dependent on the state of the rare earth in the matrix. In this work, we examine optical properties of Eu-doped 80LiF-20CaF2 eutectics for neutron detector applications based on the Eu distribution. At low concentrations, aggregation of Eu cations is observed, whereas homogeneous atomic dispersion in the CaF2 layer, to substitute Ca(2+) ions, is observed in the eutectics at high concentrations. Eu LIII edge X-ray absorption fine structure (XAFS) analysis suggests that neutron responses do not depend on the amount of Eu(2+) ions. However, transparency, which depends on an ordered lamellar structure, is found to be important for a high light yield in neutron detection. The results confirm the effectiveness of the basic idea concerning the separation of radiation absorbers and activators in particle radiation scintillation and present potential for further improvement of novel bulk detectors.

No MeSH data available.


Related in: MedlinePlus

Neutron-induced emission dynamics of Eu-doped 80LiF-20CaF2 eutectics.252Cf Neutron excited emission decay curves as a function of Eu concentrations. Inset shows the emission decay curve of the 0.1 mol%Eu-doped eutectic by the neutron irradiation.
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f2: Neutron-induced emission dynamics of Eu-doped 80LiF-20CaF2 eutectics.252Cf Neutron excited emission decay curves as a function of Eu concentrations. Inset shows the emission decay curve of the 0.1 mol%Eu-doped eutectic by the neutron irradiation.

Mentions: The luminescence spectrum of Eu-doped LiF/CaF2 eutectics following neutron irradiation has been unattainable because of power limitations of the neutron radiation source in Japan. However, from X-ray or α–ray induced spectra shown in Supplementary Fig. 4, we assume that a main emission band located around 2.9 eV is attributable to 5d-4f Eu2+ emission. This notion is also reported by another paper2122. Figure 2 shows 252Cf neutron-induced scintillation decay constants τ1/e of Eu-doped LiF/CaF2 eutectics as a function of Eu concentration. The inset image shows the neutron-induced scintillation decay curve of the 0.1 mol%Eu-doped eutectic as a typical example. The decay constant of 0.005 mol%Eu-doped LiF/CaF2 eutectic is 0.7 μs, assuring that the emission is due to the Eu2+ centre. The decay rate by neutron irradiation is almost constant below 0.1 mol% concentration, and the constant increases monotonically with increasing amounts of Eu. This indicates that a significant concentration quenching occurs around 0.1 mol% Eu. The decay constant and the tendency of an inflection point of the decay constants to be located around 0.1 mol% Eu are similar with those of X-ray scintillation decay profiles as shown in Supplementary Fig. 5.


Local coordination state of rare earth in eutectic scintillators for neutron detector applications.

Masai H, Yanagida T, Mizoguchi T, Ina T, Miyazaki T, Kawaguti N, Fukuda K - Sci Rep (2015)

Neutron-induced emission dynamics of Eu-doped 80LiF-20CaF2 eutectics.252Cf Neutron excited emission decay curves as a function of Eu concentrations. Inset shows the emission decay curve of the 0.1 mol%Eu-doped eutectic by the neutron irradiation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4544017&req=5

f2: Neutron-induced emission dynamics of Eu-doped 80LiF-20CaF2 eutectics.252Cf Neutron excited emission decay curves as a function of Eu concentrations. Inset shows the emission decay curve of the 0.1 mol%Eu-doped eutectic by the neutron irradiation.
Mentions: The luminescence spectrum of Eu-doped LiF/CaF2 eutectics following neutron irradiation has been unattainable because of power limitations of the neutron radiation source in Japan. However, from X-ray or α–ray induced spectra shown in Supplementary Fig. 4, we assume that a main emission band located around 2.9 eV is attributable to 5d-4f Eu2+ emission. This notion is also reported by another paper2122. Figure 2 shows 252Cf neutron-induced scintillation decay constants τ1/e of Eu-doped LiF/CaF2 eutectics as a function of Eu concentration. The inset image shows the neutron-induced scintillation decay curve of the 0.1 mol%Eu-doped eutectic as a typical example. The decay constant of 0.005 mol%Eu-doped LiF/CaF2 eutectic is 0.7 μs, assuring that the emission is due to the Eu2+ centre. The decay rate by neutron irradiation is almost constant below 0.1 mol% concentration, and the constant increases monotonically with increasing amounts of Eu. This indicates that a significant concentration quenching occurs around 0.1 mol% Eu. The decay constant and the tendency of an inflection point of the decay constants to be located around 0.1 mol% Eu are similar with those of X-ray scintillation decay profiles as shown in Supplementary Fig. 5.

Bottom Line: In this work, we examine optical properties of Eu-doped 80LiF-20CaF2 eutectics for neutron detector applications based on the Eu distribution.However, transparency, which depends on an ordered lamellar structure, is found to be important for a high light yield in neutron detection.The results confirm the effectiveness of the basic idea concerning the separation of radiation absorbers and activators in particle radiation scintillation and present potential for further improvement of novel bulk detectors.

View Article: PubMed Central - PubMed

Affiliation: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.

ABSTRACT
Atomic distribution in phosphors for neutron detection has not been fully elucidated, although their ionization efficiency is strongly dependent on the state of the rare earth in the matrix. In this work, we examine optical properties of Eu-doped 80LiF-20CaF2 eutectics for neutron detector applications based on the Eu distribution. At low concentrations, aggregation of Eu cations is observed, whereas homogeneous atomic dispersion in the CaF2 layer, to substitute Ca(2+) ions, is observed in the eutectics at high concentrations. Eu LIII edge X-ray absorption fine structure (XAFS) analysis suggests that neutron responses do not depend on the amount of Eu(2+) ions. However, transparency, which depends on an ordered lamellar structure, is found to be important for a high light yield in neutron detection. The results confirm the effectiveness of the basic idea concerning the separation of radiation absorbers and activators in particle radiation scintillation and present potential for further improvement of novel bulk detectors.

No MeSH data available.


Related in: MedlinePlus