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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 of Eu-doped 80LiF-20CaF2 eutectics.(a) Neutron excited pulse height spectra of LiF/CaF2 eutectics along with Li-glass as a reference. (b) 252Cf neutron excited light yield as a function of Eu concentrations together with that of non-doped sample. The transmittance is also shown as a right axis.
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f3: Neutron induced emission of Eu-doped 80LiF-20CaF2 eutectics.(a) Neutron excited pulse height spectra of LiF/CaF2 eutectics along with Li-glass as a reference. (b) 252Cf neutron excited light yield as a function of Eu concentrations together with that of non-doped sample. The transmittance is also shown as a right axis.

Mentions: Figure 3(a) depicts 252Cf neutron-induced pulse height spectra of Eu-doped LiF/CaF2 eutectics along with conventional Li-glass GS2023. Quantum efficiencies of the photomultiplier tube (PMT) at 395 nm (emission peak of GS20) and 435 nm (emission peak of Eu:LiF/CaF2) are very similar, as they both have levels around 40% when their light yields are directly compared using the value of the multichannel analyser (MCA) channel. In lower Eu-containing samples, up to Eu 0.1 mol%, which seems to be a threshold of the concentration quenching, the light yield exceeds GS20. The distribution of emission centre can be estimated from the energy resolution of the spectra by dividing the half-width half-maximum of the peak by its channel position. The translucent Eu-doped eutectics exhibit a wider distribution compared with transparent GS20, suggesting that the distribution is affected by the transparency of the sample. The distribution also increases with increasing Eu amount. Figure 3(b) shows neutron-induced absolute light yield (photon/neutron) as a function of Eu concentrations. The light yield drastically decreases above 0.1 mol% Eu-doped sample. Here, we focus on the transparency of the sample and discuss the relationship between the transparency and light yield. Both absolute light yield and transparency monotonically decrease with increasing Eu concentration.


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 of Eu-doped 80LiF-20CaF2 eutectics.(a) Neutron excited pulse height spectra of LiF/CaF2 eutectics along with Li-glass as a reference. (b) 252Cf neutron excited light yield as a function of Eu concentrations together with that of non-doped sample. The transmittance is also shown as a right axis.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: Neutron induced emission of Eu-doped 80LiF-20CaF2 eutectics.(a) Neutron excited pulse height spectra of LiF/CaF2 eutectics along with Li-glass as a reference. (b) 252Cf neutron excited light yield as a function of Eu concentrations together with that of non-doped sample. The transmittance is also shown as a right axis.
Mentions: Figure 3(a) depicts 252Cf neutron-induced pulse height spectra of Eu-doped LiF/CaF2 eutectics along with conventional Li-glass GS2023. Quantum efficiencies of the photomultiplier tube (PMT) at 395 nm (emission peak of GS20) and 435 nm (emission peak of Eu:LiF/CaF2) are very similar, as they both have levels around 40% when their light yields are directly compared using the value of the multichannel analyser (MCA) channel. In lower Eu-containing samples, up to Eu 0.1 mol%, which seems to be a threshold of the concentration quenching, the light yield exceeds GS20. The distribution of emission centre can be estimated from the energy resolution of the spectra by dividing the half-width half-maximum of the peak by its channel position. The translucent Eu-doped eutectics exhibit a wider distribution compared with transparent GS20, suggesting that the distribution is affected by the transparency of the sample. The distribution also increases with increasing Eu amount. Figure 3(b) shows neutron-induced absolute light yield (photon/neutron) as a function of Eu concentrations. The light yield drastically decreases above 0.1 mol% Eu-doped sample. Here, we focus on the transparency of the sample and discuss the relationship between the transparency and light yield. Both absolute light yield and transparency monotonically decrease with increasing Eu concentration.

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