Author’s Accepted Manuscript
Scintillation properties of TGG and TSAG crystalsfor imaging applications
Takayuki Yanagida, Go Okada, Takahiro Kojima,Takeshi Hayashi, Jisaburou Ushizawa, NaokiKawano, Noriaki Kawaguchi
PII: S0921-4526(17)30255-7DOI: http://dx.doi.org/10.1016/j.physb.2017.05.029Reference: PHYSB309953
To appear in: Physica B: Physics of Condensed Matter
Received date: 14 April 2017Revised date: 13 May 2017Accepted date: 15 May 2017
Cite this article as: Takayuki Yanagida, Go Okada, Takahiro Kojima, TakeshiHayashi, Jisaburou Ushizawa, Naoki Kawano and Noriaki Kawaguchi,Scintillation properties of TGG and TSAG crystals for imaging applications,Physica B: Physics of Condensed Matter,http://dx.doi.org/10.1016/j.physb.2017.05.029
This is a PDF file of an unedited manuscript that has been accepted forpublication. As a service to our customers we are providing this early version ofthe manuscript. The manuscript will undergo copyediting, typesetting, andreview of the resulting galley proof before it is published in its final citable form.Please note that during the production process errors may be discovered whichcould affect the content, and all legal disclaimers that apply to the journal pertain.
www.elsevier.com/locate/physb
1
Scintillation properties of TGG and TSAG crystals for imaging applications
Takayuki Yanagida1,*
, Go Okada1, Takahiro Kojima
2, Takeshi Hayashi
2, Jisaburou
Ushizawa2, Naoki Kawano
1, Noriaki Kawaguchi
1
1Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5
Takayama, Ikoma, Nara 630-0192, Japan
2Oxide Corporation, 1747-1 Mukawa, Hokuto, Yamanashi 408-0302, Japan
*Corresponding author: 8916-5 Takayama, Ikoma, Nara 630-0192, Japan. Tel. +81-743-72-6144 /
Fax. +81-743-72-6147. E-mail [email protected]
Abstract:
Optical and scintillation properties of TGG (Tb3Ga5O12) and TSAG (Tb3Sc2Al3O12) crystals were
investigated, and capabilities to be used as a scintillator screen were demonstrated. In
photoluminescence (PL) spectra, some emission lines due to Tb3+
4f-4f transitions appeared from
500 to 700 nm. PL quantum yields of TGG and TSAG were 6.5 and 50.9%, respectively. When
irradiated by X-rays, these crystals showed intense scintillation, and the emission wavelengths were
the same as those in PL spectra. The scintillation decay times of TGG and TSAG were 94 and 678 ms,
respectively. Further, we have demonstrated X-ray imaging using both TSGG and TSAG crystal plates
and confirmed a capability as scintillator screens.
Keywords:
2
TGG; TSAG; X-rays; Scintillation; Scintillator screen
1. Introduction
Scintillators have a function to absorb the energy of invisible ionizing radiations, and convert the
energy to luminescence immediately [1]. This luminescence is generally detected by photodetectors
such as photomultiplier tube (PMT) or some photodetectors composed of Si, and is converted to
electrons. Such kinds of devices consisting of the scintillator and the photodetector are called
scintillation detectors. The range of applications of scintillation detectors are very wide including
nuclear medicine [2], X-ray computed tomography (CT) [3], security [4], oil-logging [5], astrophysics
[6] and particle physics [7]. In the viewpoint of detection techniques, scintillation detectors are
classified to two types such as the photon-integration-type and photon-counting-type detectors.
The integration-type detectors accumulate many radiation detection events and read out signals as
an integrated value typically within several ms. On the other hand, the counting-type detectors
process each radiation detection event and read out the signal by one incident radiation. The
former types are typically used in imaging detectors for X-ray CT [3] and scintillator screens [8-11].
Detectors of the latter type are used in nuclear medicine and high energy physics. In these
scintillation detectors, properties of scintillator materials are essentially important, and continuous
effort has been given to discover new efficient scintillators.
In this study, we will report basic optical and scintillation properties of newly developed
3
scintillators such as TGG (Tb3Ga5O12) and TSAG (Tb3Sc2Al3O12) crystals prepared by Oxide Corp.
Tb-based aluminum garnet such as TAG (Tb3Al5O12) has been investigated on the optical isolator
applications using the Faraday rotation [12-14]. To study optical isolator properties, some other
Tb-based garnet materials such as TGG [15] and TSAG [16] have been developed. In addition to
magneto-optical applications, Tb-based materials are applicable for scintillator applications. The
most common Tb-based materials is Tb-doped Gd2O2S (Tb:GOS) [8], and Tb:GOS has been widely
used in integrated-type imaging detectors such as scintillator screen. When Tb-doped materials are
irradiated by ionizing radiation, they show an intense green-yellow emission, and the emission
wavelength is well-suited to Si-semiconductor-based photodetectors. Although Tb is used as an
emission center in the case of Tb:GOS, Tb is relatively free from the concentration quenching so
Tb-based materials can also show efficient luminescence. Actually, one of the common Tb-based
garnet materials, TAG, is reported to have efficient luminescence properties [9, 17-19] when Ce is
activated as an emission center, and Ce-doped TAG thin film is examined in scintillator screen
application [9]. However, no investigations can be found about TGG and TSAG on scintillation
properties and screen application capabilities. In addition, most reports on luminescent properties
of Tb-based garnets have been carried out by Ce-doped TAG, and emission properties due to Tb3+
in
Tb-based garnet materials have not been investigated.
Throughout this work, optical and scintillation properties of TGG and TSAG have been
4
investigated. To our knowledge, the report on the scintillation properties of TGG and TSAG is for the
first time. In addition, a demonstration as scintillation screen was performed for potential
applications for X- and g-ray detectors.
2. Experimental
TGG and TSAG crystals were synthesized by Oxide Corp. with the following procedures. TGG and
TSAG single crystals were grown by the Czochralski method with RF induction heater. As starting
materials Tb4O7 and Ga2O3 were used for TGG. Tb4O7, Sc2O3 and Al2O3 were used for TSAG. Purities
of these powders were 99.99%. They were mixed to garnet composition and loaded into an Ir
crucible. Single crystals were grown on <111> seed crystal with a pulling rate of 0.4-2 mm/h and a
speed of crystal rotation of 2-10 rpm. As-grown crystals were annealed at 1500-1550 °C in air
before cutting.
Optical properties were characterized as follows. In-line transmittance spectra were collected by
JASCO V670 spectrometer from 190 to 2500 nm. A photoluminescence (PL) emission map was
evaluated by using Quantaurus-QY (Hamamatsu), and PL internal quantum yields (QY) were
obtained at the same time. The internal QY was calculated by the following equation, QY =
Nemit/Nabsorb where Nemit and Nabsorb were numbers of emission and absorption photons, respectively.
In this evaluation, the Nabsorb was an integration of photons from 250 to 270 nm and Nemit was from
5
450 to 650 nm. The PL decay time profiles were evaluated by Quantaurus-t, and the excitation and
the monitoring wavelengths were 265 and 470 nm, respectively.
Scintillation properties were characterized as follows. X-ray induced radioluminescence spectra
were observed by using our original setup [20]. The excitation source was an X-ray tube equipped
with W anode. The supplied bias voltage and tube current were 40 kV and 5.2 mA, respectively.
When X-ray is absorbed by the scintillator, scintillation photons are immediately emitted, and these
photons were detected by CCD detector (Andor DU420) via monochromator (Andor SR163) to
obtain a spectrum. The scintillation decay time profiles were also evaluated by our original
instrument [21]. The root of the excitation source was a timing and pulse width controlled LED, and
photons from LED was converted to photoelectrons at the photocathode of pulse X-ray tube. These
generated electrons were accelerated by 30 kV bias voltage, and they emit X-rays under the
interaction with W target via Bremsstrahlung. Thus the pulse timing was generated by the root LED,
and the endpoint energy was 30 keV. By using the same equipment, we also measured X-ray
induced afterglow profiles of two samples. In order to confirm the observed afterglow profiles, we
measured thermally stimulated luminescence (TSL) glow curves by using TL-2000 (Nanogray) [22]
with the heating rate of 1 °C/s.
Last, we demonstrated X-ray imaging using the TAG and TSAG samples as scintillator screens.
The setup is illustrated in Figure 1. The object sample was placed between the X-ray generator and
6
scintillator. Scintillation light emitted was guided to the CCD camera (BU-54DUV, Bitran Inc.) by the
first reflection mirror. The objective lens equipped on the camera was UV-105mmF4.5, Nikon. This
configuration prevents from X-ray photons directly striking to the CCD camera.
3. Results and discussion
Figure 2 shows a picture of the samples under room right and UV irradiation by the UV-lamp.
The sample size was 10 × 10 × 2 mm3. The wide surfaces were polished and these samples were
visually transparent. When 365 nm UV photons were irradiated to the samples, yellow-green
emissions were observed by naked eyes. As clearly demonstrated in the figure, TSAG showed higher
emission intensity.
Figure 3 demonstrates in-line transmittance of TGG and TSAG. Except for some sharp
absorption lines due to 4f-4f transitions of Tb3+
, typical transmittance values of TGG and TSAG were
75 and 80% from 400 to 1200 nm, respectively. In the visible wavelength, the sharp absorption line
at 484 nm was due to the 7F6 ->
5D4 transition of Tb
3+. In the shorter wavelength, two strong
absorption bands were observed around 280 and 325 nm due to the transitions from 7F6 to 5d
levels (7E and
9E) of Tb
3+, respectively. No broad absorption bands due to the charge transfer of Tb
4+
were observed in the UV and visible ranges so Tb4+
was not generated in the crystal growth
processes.
7
PL emission maps of TGG and TSAG are shown in Figure 4. Some sharp emission lines due to
Tb3+
4f-4f transition were observed especially in TSAG. In the case of TSAG, four intense emission
lines appeared around 470, 550, 580 and 625 nm, and the corresponding electron transitions were
from 5D4 to
7F6,
7F5,
7F4 and
7F3, respectively. The weak lines around 670 nm would be
5D4 ->
7F2,1
transitions. In TGG, three emission lines around 550, 580 and 625 nm were detected. The internal
QY of TGG and TSAG were 6.5 ± 2 and 50.9 ± 2%, respectively. The PL QY of TSAG was largely higher
than that of TGG, and this result was consistent with Figure 1.
PL decay time profiles of TGG and TSAG are displayed in Figure 5. In order to avoid to detect
the diffraction light, we selected to observe 470 nm emission line. Although the emission intensity
of TGG was very weak, the coincidence measurement enabled us to observe the decay curve of
TGG clearly. The decay curve of TGG was reproduced by the triple exponential approximation, and
the deduced decay times were 0.1, 1.1 and 12.2 ms. On the other hand, TSAG could be
approximated by the single exponential function, and the decay time resulted 1.1 ms. The shortest
component in the TGG is ascribed to the excitation pulse of the equipment, and the longest one
would be due to some kinds of defects since the typical decay times of emission due to Tb3+
4f-4f
transition are from several hundred ms to a few ms [23, 24].
Figure 6 represents X-ray induced radioluminescence spectra of TGG and TSAG. Although the
radioluminescence intensity is a qualitative value, the intensities were compared between these
8
two samples since the sample size is the same and the effective atomic numbers are equivalent. As
a result, TSAG showed higher emission intensity than that of TGG. The emission wavelengths of
TSAG were the same as those in PL, and the wavelengths were 470, 550, 580, 625 and 670 nm. The
electron transitions of these emission lines were also the same as those in PL, 5D4 ->
7Fi (i = 1-6)
transitions. Among these emission lines, the 550 nm peak due to 5D4 ->
7F5 transition was the
strongest. The intensities of the latter emission in TGG and TSAG differed approximately by one
order of magnitude. In fact, this difference corresponds to the difference of PL QYs. Scintillation
light yields are understood to be a product of the energy migration efficiency from the host and QY
of emission centers [25-28]. In TGG and TSAG, the former term is on a similar level since the
observed ratios of radioluminescence intensities to PL QYs are the almost same. From the
viewpoint of detector applications, since the main emission wavelengths are green-yellow
wavelengths, the matching with Si-based detectors such as Si-photodiode or CCD will be adequate
for TGG and TSAG.
Scintillation decay time profiles are presented in Figure 7. The delta function like component in
this measurement was due to the instrumental response of the detector system. The main
scintillation decay components of TGG and TSAG were 94 and 678 ms, respectively. These decay
times are faster than those in PL decay, and the possible reasons are as follows. One is the
difference of detected emissions. In PL, we only observed the 470 nm emission while, in
9
scintillation, all the emitted photons from 160 to 650 nm were integrated. Since the time correlated
single photon counting was conducted in these measurements, some emissions of garnet host
which was not observed in the spectra may be also detected in these decay curves. Generally, the
garnet host emissions are faster than those from Tb3+
4f-4f transitions [29], and if the emissions
from the host and Tb3+
4f-4f transitions are merged, the observed decay curves look faster. The
other is the energy migration path. In PL, we only observe the excitation and relaxation of localized
emission centers while some additional processes are involved in scintillation. In the case that
scintillation decay is faster than PL, it is typically interpreted that some competitions between the
energy transfer and quenching due to interactions among energetic secondary electrons might
occur. Although the observations of Tb3+
emissions in ms range are limited due to the difficulty of
the measurement, some reports can be found. For example, main decay time of Tb-doped
12CaO-7Al2O3 crystal was around 2 ms [30] and Tb-doped NaPO3-Al(PO3)3 glass was around 800 ms
[31]. Compared with these previous works, decay times of TGG and TSAG were significantly fast,
and it was blamed for the concentration quenching of scintillation since Tb was a main element in
these compounds.
Figure 8 shows afterglow time profiles of the samples with 2 ms X-ray irradiation. The
afterglow level of TSAG was higher than that of TGG by more than one-order of magnitude. In order
to understand the afterglow profiles, TSL glow curves of these two samples are compared in the
10
inset of Figure 8. In the TSL glow curves, TGG showed a glow peak around 400 °C while TSAG
showed a glow peak around 200 °C. From these results, we understand that the high afterglow level
of TSAG is originated from a larger concentration of shallow traps included in TSAG than TGG.
Compared with the conventional scintillators such as BGO and CWO [21], the afterglow levels of
TGG and TSAG were higher. Although these materials were not suited for the application of X-ray
inspections systems in airports by such a high afterglow levels, they can be applied for other
integrated type radiation detectors.
Figure 9 demonstrates X-ray imaging using TGG and TSAG samples. The sample and OP Amp.
are firmly held by a Kapton tape during the experiments. Under X-ray irradiation, strong
luminescence was observed and the internal circuit patterns of OP. amp chip were clearly visualized.
Therefore, we confirmed that TGG and TSAG crystal scintillators are applicable for scintillator screen
applications. The image qualities by TGG and TSAG were similar but an image contrast using TSAG
seems to be slightly better due to higher scintillation intensity. The spatial resolution strongly
depends on the S/N [32], thus the contrast of the Kapton tape of TSAG screen was higher than that
of TGG screen.
4. Conclusion
Optical, scintillation and scintillation screen detector properties of TGG and TSAG were
11
investigated. In PL and radioluminescence spectra, intense emission lines appeared 470, 550, 580,
625 and 670 nm due to 5D4 ->
7Fi (i = 1-6) transitions in both samples. The radioluminescence
intensity of TSAG was one digit higher than that of TGG. The scintillation decay times of TGG and
TSAG were 94 and 678 ms, respectively. In scintillation screen experiments, we confirmed that TGG
and TSAG worked as a scintillation screen, and the contrast of TSAG screen was better than that of
TGG. Throughout this work, the capability of TGG and TSAG for scintillator screen is confirmed.
Acknowledgement
This work was supported by a Grant in Aid for Scientific Research (A)-26249147 from the Ministry of
Education, Culture, Sports, Science and Technology of the Japanese government (MEXT) and
partially by JST A-step. The Cooperative Research Project of Research Institute of Electronics,
Shizuoka University, KRF foundation, Hitachi Metals Materials Science foundation, and Inamori
foundation are also acknowledged.
References
[1] T. Yanagida, "Study of rare-earth-doped scintillators" Opt. Mat., 35 1987-1992 (2013).
[2] T. Yanagida, A. Yoshikawa, Y. Yokota, K. Kamada, Y. Usuki, S. Yamamoto, M. Miyake, M. Baba, K.
12
Sasaki, M. Ito "Development of Pr:LuAG Scintillator Array and Assembly for Positron Emission
Mammography" IEEE. Nucl. Trans. Sci.,57, 1492-1495 (2010)
[3] L. Zhang, T. YangDai, “Determination of liquid's molecular interference function based on X-ray
diffraction and dual-energy CT in security screening”, Applied Radiation and Isotopes, 114,
179-187 (2016).
[4] D. Totsuka, T. Yanagida, K. Fukuda, N. Kawaguchi, Y. Fujimoto, Y. Yokota, A. Yoshikawa,
"Performance test of Si PIN photodiode line scanner for thermal neutron detection" Nucl.
Instrum. Methods A, 659 399-402 (2011).
[5] T. Yanagida, Y. Fujimoto, S. Kurosawa, K. Kamada, H. Takahashi, Y. Fukazawa, M. Nikl, V. Chani
"Temperature dependence of scintillation properties of bright oxide scintillators for
well-logging" Jpn. J. Appl. Phys., 52, 076401 (2013).
[6] M.Kokubun, K.Abe, Y.Ezoe, Y.Fukazawa, S.Hong, H.Inoue, T.Itoh, T.Kamae, D.Kasama,
M.Kawaharada, N.Kawano, K.Kawashima, S.Kawasoe, Y.Kobayashi, J.Kotoku, M.Kouda,
A.Kubota, G.M.Madejski, K.Makishima, T.Mitani, H.Miyasaka, R.Miyawaki, K.Mori, M.Mori,
T.Murakami, M.M.Murashima, K.Nakazawa, H.Niko, M.Nomachi, M.Ohno, Y.Okada, K.Oonuki,
G.Sato, M.Suzuki, H.Takahashi, I.Takahashi, T.Takahashi, K.Tamura, T.Tanaka, M.Tashiro, Y.Terada,
S.Tominaga, S.Watanabe, K.Yamaoka, T.Yanagida, and D.Yonetoku, "Improvements of the
Astro-E2 Hard X-ray Detector (HXD-II)'', IEEE Trans. Nucl. Sci., 51, 1991-1996 (2004).
13
[7] T. Ito, T. Yanagida, M. Sato, M. Kokubun, T. Takashima, S. Hirakuri, R. Miyawaki, H. Takahashi, K.
Makishima, T. Tanaka, K. Nakazawa, T. Takahashi, T. Honda, "A 1-Dimensional Gamma-ray
Position Sensor based on GSO:Ce Scintillators Coupled to a Si Strip Detector", Nucl. Instr. and
Meth. A, 579, 239-241 (2007).
[8] J. Kim, B. K. Cha, J. H. Bae, C. Lee, H. Kim, S. Chang, G. Cho, C. Sim, T. Kim, “Fabrication and
characterization of pixelated Gd2O2S:Tb scintillator screens for digital X-ray imaging
applications”, Nucl. Instrum. Methods A, 633 S303-S306 (2011).
[9] Y. Zorenko, P. Douissard, T. Martin, F. Riva, V. Gorbenko, T. Zorenko, K. Paprocki, A. Iskalieva, S.
Witkiewicz, A. Fedorov, P. Bilski, A. Twardak, “Scintillating screens based on the LPE grown
Tb3Al5O12:Ce single crystalline films”, Opt. Mater., in press (2016).
[10] B. K. Cha, S. J. Lee, P. Muralidharan, J. Y. Kim, D. K. Kim, G. Cho, “Characterization and imaging
performance of nanoscintillator screen for high resolution X-ray imaging detectors”, Nucl.
Instrum. Methods A, 633 S294-S296 (2011).
[11] J. Touš, K. Blažek, L. Pína, B. Sopko, “High-resolution X-ray imaging CCD camera based on a thin
scintillator screen”, Radiat. Meas., 42 925-928 (2007).
[12] J. Dai, I.L. Snetkov, O.V. Palashov, Y. Pan, H. Kou, J. Li, “Fabrication, microstructure and
magneto-optical properties of Tb3Al5O12 transparent ceramics”, Opt. Mater., 62 205-210
(2016).
14
[13] H. Lin, S. Zhou, H. Teng, “Synthesis of Tb3Al5O12 (TAG) transparent ceramics for potential
magneto-optical applications”, Opt. Mater., 33 1833-1836 (2011).
[14] C. Chen, X. Yi, S. Zhang, Y. Feng, Y. Tang, H. Lin, S. Zhou, “Vacuum sintering of Tb3Al5O12
transparent ceramics with combined TEOS+MgO sintering aids”, Ceramics International 41
12823–12827 (2015).
[15] N. Zhuang, C. Song, L. Guo, R. Wang, X. Hu, B. Zhao, S. Lin, J. Chen, “Growth of terbium gallium
garnet (TGG) magneto-optic crystals by edge-defined film-fed growth method”, J. Cryst.
Growth, 381 27-31 (2013).
[16] I. Snetkov, O. Palashov, “Faraday isolator based on a TSAG single crystal with compensation of
thermally induced depolarization inside magnetic field”, Opt. Mater., 42, 293-297 (2015).
[17] M. Batentschuk, A. Osvet, G. Schierning, A. Klier, J. Schneider, A. Winnacker, “Simultaneous
excitation of Ce3+
and Eu3+
ions in Tb3Al5O12”, Radiat. Meas., 38 539–543 (2004).
[18] Y. Onishi, T. Nakamura, S. Adachi, “Luminescence properties of Tb3Al5O12 garnet and related
compounds synthesized by the metal organic decomposition method”, J. Lumin., 183 193-200
(2017).
[19] Y. Chen, M. Gong, G. Wang, Q. Su, “High efficient and low color-temperature white
light-emitting diodes with Tb3Al5O12:Ce3+
phosphor”, J. Appl. Phys., 91, 071117 (2007).
[20] T. Yanagida, K. Kamada, Y. Fujimoto, H. Yagi, T. Yanagitani "Comparative study of ceramic and
15
single crystal Ce:GAGG scintillator" Opt. Mater., 35 2480-2485 (2013).
[21] T. Yanagida, Y. Fujimoto, T. Ito, K. Uchiyama, K. Mori "Development of X-ray induced afterglow
characterization system" Appl. Phys. Exp., 7 062401 (2014).
[22] T. Yanagida, Y. Fujimoto, N. Kawaguchi, S. Yanagida "Dosimeter properties of AlN" J. Ceram.
Soc. Jpn., 121 988-991 (2013).
[23] G. Gao, A. Winterstein-Beckmann, O. Surzhenko, C. Dubs, J. Dellith, M. A. Schmidt, “Faraday
rotation and photoluminescence in heavily Tb3+
-doped GeO2-B2O3-Al2O3-Ga2O3 glasses for
fiber-integrated magneto-optics”, Scientific Reports 5, 8942 (2015).
[24] M. Runowski, K. Dąbrowska, T. Grzyb, P. Miernikiewicz, S. Lis, “Core/shell-type nanorods of
Tb3+
-doped LaPO4, modified with amine groups, revealing reduced cytotoxicity”, J. Nanopart.
Res., 15, 2068 (2013).
[25] D. J. Robbins, “On Predicting the Maximum Efficiency of Phosphor Systems Excited by Ionizing
Radiation”, J. Electrochem. Soc. 127 (1980) 2694.
[26] A. Lempicki, A. J. Wojtowicz, E. Berman, “Fundamental limits of scintillator performance”, Nucl.
Instrum. Methods A, 333 (1993) 304.
[27] P. A. Rodnyi, P. Dorenbos, C. W. E. van Eijk, “Energy Loss in Inorganic Scintillators”, Phys. Status
Solidi (c), 187 (1995) 15.
[28] P. Dorenbos, Fundamental Limitations in the Performance of Ce3+
–, Pr3+
–, and Eu2+
–Activated
16
Scintillators, IEEE Trans. Nucl. Sci., 57 (2000) 1162-1167.
[29] Y. Fujimoto, T. Yanagida, H. Yagi, T. Yanagitani, V. Chani, “Comparative study of intrinsic
luminescence in undoped transparent ceramic and single crystal garnet scintillators” Opt.
Mater., 36 1926-1929 (2014).
[30] N. Kumamoto, D. Nakauchi, T. Kato, G. Okada, N. Kawaguchi, T. Yanagida, “Photoluminescence,
Scintillation and Thermally-Stimulated Luminescence Properties of Tb-doped 12CaO-7Al2O3
Single Crystals Grown by the FZ Method”, J. Rare Earths, accepted (2017).
[31] T. Kuro, G. Okada, N. Kawaguchi, Y. Fujimoto, H. Masai, T. Yanagida, “Scintillation properties of
rare-earth doped NaPO3-Al(PO3)3 glasses”, Opt. Mater., 62 561-568 (2016).
[32] S. Kasap, J. B. Frey, G. Belev, O. Tousignant, H. Mani, J. Greenspan, L. Laperriere, O. Bubon, A.
Reznik, G. DeCrescenzo, K. S. Karim, J. A. Rowlands, “Amorphous and Polycrystalline
Photoconductors for Direct Conversion Flat Panel X-Ray Image Sensors”, Sensor., 11 (2011)
5112-5157
Figure captions
Figure 1 Schematic drawing of the experimental setup for scintillator screen measurement.
Figure 2 Pictures of TGG and TSAG under room light (left) and UV irradiation by UV-lamp (right).
Figure 3 Optical in-line transmittance of TGG and TSAG.
17
Figure 4 PL emission map of TGG (top) and TSAG (bottom). The horizontal axis is the emission
wavelength, and the vertical axis is the excitation wavelength.
Figure 5 PL decay time profiles of TGG and TSAG monitoring at 470 nm under 265 nm excitation.
Figure 6 X-ray induced radioluminescence spectra of TGG and TSAG.
Figure 7 Scintillation decay time profiles of TGG and TSAG under pulse X-ray excitation.
Figure 8 Afterglow profiles of TGG and TSAG, and inset shows TSL glow curves of these two
samples after 1 Gy X-ray irradiation.
Figure 9 Sample object of the scintillator screen experiment (left) and observed images by using
TGG and TSAG (right).
Figure 1
Figure
Figure 2
TSAG TGG TSAG TGG
UV
irradiation
Figure 3
Figure 4 250
300
350
400
450
Ex
cita
tio
n W
avel
eng
th, n
m
250
300
350
400
450
400 600 500 800 700
Emission Wavelength, nm
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9