The luminescence properties of Ce- or Ce and La-doped gadolinium pyrosilicate （Gd2Si2OT, GPS） were characterized using vacuum ultraviolet （VUV） excitation light. A prominent emission band was observed in the lumin...The luminescence properties of Ce- or Ce and La-doped gadolinium pyrosilicate （Gd2Si2OT, GPS） were characterized using vacuum ultraviolet （VUV） excitation light. A prominent emission band was observed in the luminescence spectra with excitation at 60 nm and ascribed to 5d-4f transition of Ce3＋. Because the excitation wavelength of 60 nm corresponded to the excitation in the host matrix, this result indicated that the excitation energy transfer occurred from the host matrix to Ce3＋ ions. On the basis of the rise in the luminescence time profiles with excitation at 60 nm, the energy transfer occurred within 2 ns, which was much shorter than that of Ce-doped Gd2SiO2. For Ce-doped GPS, the decay rate was slower for the host excitation than that for direct excitation of Ce3＋. In contrast, for Ce and La-doped GPS, no significant difference was observed for the host excitation and direct excitation of Ce3＋. This result indicated that the energy transfer from the host to Ce3＋ ions led to a different radiative decay process, and that La doping had an effect on the energy transfer and decay process.展开更多
Two topics were focused. The first one was about the gamma-ray scintillator, Pr^3＋：Lu3Al5O12 （LuAG）. The second one was about neutron scintillator, Ce^3＋：^6LiCaAlF6 and Eu^2＋：^6LiCaAlF6 （^6LiCAF）. Those scin...Two topics were focused. The first one was about the gamma-ray scintillator, Pr^3＋：Lu3Al5O12 （LuAG）. The second one was about neutron scintillator, Ce^3＋：^6LiCaAlF6 and Eu^2＋：^6LiCaAlF6 （^6LiCAF）. Those scintillators have been developed very recently for modem imaging applications in the medical and homeland security fields. In both cases, the rare earth ions are playing the crucial role as emission centers. Pr^3＋ in LuAG provided fast 5d→4f transition providing noticeably shorter decay time than that of Ce^3＋. Among several candidate hosts, LuAG showed the best performance. Bulk crystal growth, basic scintillation properties, two-dimensional gamma-ray imaging and positron emission mammography （PEM） application were demonstrated. Due to the international situation, the homeland security was compromized by illicit traffic of explosives, drugs, nuclear materials, etc. and the ways to its improvement became an important R＆D topic. For this purpose the Ce and Eu doped LiCAF appeared competitive candidates. Especially, when substitution of 3He neutron detectors was considered, the discrimination ability of gamma-ray from alpha-ray was important. Bulk crystal growth, basic scintillation properties and two-dimensional neutron imaging were demonstrated.展开更多
基金supported by the Joint Studies Program (2014, No. 26–546) of the Institute for Molecular Sciencesupported by the SPRITS program, Kyoto Universitythe Cooperative Research Project of Research Institute of Electronics, Shizuoka University
文摘The luminescence properties of Ce- or Ce and La-doped gadolinium pyrosilicate （Gd2Si2OT, GPS） were characterized using vacuum ultraviolet （VUV） excitation light. A prominent emission band was observed in the luminescence spectra with excitation at 60 nm and ascribed to 5d-4f transition of Ce3＋. Because the excitation wavelength of 60 nm corresponded to the excitation in the host matrix, this result indicated that the excitation energy transfer occurred from the host matrix to Ce3＋ ions. On the basis of the rise in the luminescence time profiles with excitation at 60 nm, the energy transfer occurred within 2 ns, which was much shorter than that of Ce-doped Gd2SiO2. For Ce-doped GPS, the decay rate was slower for the host excitation than that for direct excitation of Ce3＋. In contrast, for Ce and La-doped GPS, no significant difference was observed for the host excitation and direct excitation of Ce3＋. This result indicated that the energy transfer from the host to Ce3＋ ions led to a different radiative decay process, and that La doping had an effect on the energy transfer and decay process.
基金Project supported by Japan Science and Technology Agency,Regional Research and Development Resources Utilization Program,Ministry of Education,Culture,Sports,Science and Technology of Japanese government,Grant-in-Aid for Young Scientists (A)the joint project between JSPS and ASCR (19686001 (AY))+2 种基金Czech GAAV Project (M100100910)the Funding Program for Next Generation World-Leading ResearchersJapan Society for Promotion of Science
文摘Two topics were focused. The first one was about the gamma-ray scintillator, Pr^3＋：Lu3Al5O12 （LuAG）. The second one was about neutron scintillator, Ce^3＋：^6LiCaAlF6 and Eu^2＋：^6LiCaAlF6 （^6LiCAF）. Those scintillators have been developed very recently for modem imaging applications in the medical and homeland security fields. In both cases, the rare earth ions are playing the crucial role as emission centers. Pr^3＋ in LuAG provided fast 5d→4f transition providing noticeably shorter decay time than that of Ce^3＋. Among several candidate hosts, LuAG showed the best performance. Bulk crystal growth, basic scintillation properties, two-dimensional gamma-ray imaging and positron emission mammography （PEM） application were demonstrated. Due to the international situation, the homeland security was compromized by illicit traffic of explosives, drugs, nuclear materials, etc. and the ways to its improvement became an important R＆D topic. For this purpose the Ce and Eu doped LiCAF appeared competitive candidates. Especially, when substitution of 3He neutron detectors was considered, the discrimination ability of gamma-ray from alpha-ray was important. Bulk crystal growth, basic scintillation properties and two-dimensional neutron imaging were demonstrated.
