Current trends in scintillator detectors and materials

doi:10.1016/S0168-9002(02)00955-5

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Volume 487, Issues 1–2, 11 July 2002, Pages 123-128

https://doi.org/10.1016/S0168-9002(02)00955-5 Get rights and content

Abstract

The last decade has seen a renaissance in inorganic scintillator development for gamma ray detection. Lead tungstate (PbWO₄) has been developed for high-energy physics experiments, and possesses exceptionally high density and radiation hardness, albeit with low luminous efficiency. Lutetium orthosilicate or LSO (Lu₂SiO₅:Ce) possesses a unique combination of high luminous efficiency, high density, and reasonably short decay time, and is now incorporated in commercial positron emission tomography cameras. There have been advances in understanding the fundamental mechanisms that limit energy resolution, and several recently discovered materials (such as LaBr₃:Ce) possess energy resolution that approaches that of direct solid state detectors. Finally, there are indications that a neglected class of scintillator materials that exhibit near band-edge fluorescence could provide scintillators with sub-nanosecond decay times and high luminescent efficiency.

Introduction

This paper attempts to summarize some of the recent developments in scintillator materials. Most applications desire the same properties for an “ultimate” scintillator (high density and atomic number, high light output, short decay time without afterglow, convenient emission wavelength, mechanical ruggedness, radiation hardness, and low cost), but the lack of a perfect material has resulted in a number of different scintillators being developed and used for different applications [1], [2]. This paper briefly describes two such scintillation materials that have been developed in the past decade for use in high-energy physics and nuclear medical imaging. The properties of one of these materials spurred the investigation of the fundamental mechanisms that limit energy resolution, and has lead to some newly discovered scintillation materials that have unprecedented energy resolution. Finally, there has been recent revived interest in a scintillation mechanism that appears capable of producing scintillation materials that are both fast and luminous.

Section snippets

Lead tungstate

The present generation of high-energy physics experiments requires levels of radiation hardness >10⁶ rads, a level unreached by existing materials. Short decay time is required because of the high bunch crossing (i.e. event) rate, but the high photon energies involved imply that materials with low scintillation efficiency can be used. The Crystal Clear Collaboration initially developed CeF₃ to meet these needs [3]; CeF₃ possesses a light output of 4000 photons/MeV, a decay time of 27 ns, and a 1.7

Lutetium orthosilicate

Many other applications, such as nuclear medical imaging, well logging, and treaty verification, desire to do gamma ray spectroscopy at high rates. There have been a number of Ce³⁺-doped materials developed in the past decade that provide this, and lutetium-based materials appear to yield particularly good properties [2]. The best known example is lutetium orthosilicate (usually known as LSO or Lu₂SiO₅:Ce), which has a light output of 25,000 photons/MeV, a decay time of 40 ns, and a density of

Non-proportionality

One aspect of LSO's performance has puzzled researchers—although it has a high luminous efficiency, its energy resolution is significantly worse than is expected from counting statistics. Many alkali–halide scintillators (including NaI:Tl and CsI:Tl) also share this undesirable feature and there has been a recent revival in efforts to understand this effect. Fig. 1 plots, for a variety of alkali–halide and non-alkali–halide scintillators, the energy resolution (for 662 keV gamma ray excitation)

Energy resolution

In the past few years, a number of other materials that have been investigated have extremely promising properties, including LaBr₃:Ce [13], LaCl₃:Ce [14], and RbGd₂Br₇:Ce [15]. These materials possess high luminous efficiency with excellent energy resolution and fast (∼50 ns) decay time, but have relatively low density (∼5 g/cc) and atomic number. Of these, LaBr₃:Ce is probably the most promising material, with a light output of 61,000 photons/MeV (50% higher than NaI:Tl), a primary decay time

Scintillation from wide band-gap semiconductors

Most inorganic scintillators used today are based on insulating host crystals in which luminescent ions or complexes are imbedded. Sometimes the luminescent centers are intrinsic, such as the cerium in CeF₃ or the tungstate complex in cadmium tungstate (CdWO₄), and sometimes they are dopants, such as the thallium in NaI:Tl or cerium in LSO. In these materials, the ionizing radiation initially forms holes in the valence band and electrons in the conduction band, with enough energy being

Conclusion

There has been a significant amount of recent progress in scintillators. New materials for high-energy physics and positron emission tomography (lead tungstate and LSO, respectively) have recently completed the “development” phase of research and development and have just entered large-scale production. There have been significant efforts to understand the fundamental limits of energy resolution in scintillators, and it recently has been shown that the energy-dependent nature of the

Acknowledgements

I would like to thank several people for providing me with the data that is included in this paper, including E. Auffray, P. Dorenbos, J. Valentine, and S. Derenzo. This work was supported in part by the Director, Office of Science, Office of Biological and Environmental Research, Medical Science Division of the US Department of Energy under Contract No. DE-AC03-76SF00098 and in part by Public Health Service grant number R01 CA48002 awarded by the National Cancer Institutes, Department of

References (18)

E. Auffray et al.
Extensive studies on CeF3 crystals, a good candidate for electromagnetic calorimetry at future accelerators
Nucl. Instr. and Meth. A
(1996)
P. Lecoq et al.
Lead tungstate (PbWO₄) scintillators for LHC EM calorimetry
Nucl. Instr. and Meth. A
(1995)
W.W. Moses et al.
PET detector modules based on novel detector technologies
Nucl. Instr. and Meth. A
(1994)
P. Dorenbos
Light output and energy resolution of Ce3+ doped scintillators
Nucl. Instr. and Meth. A
(2002)
W. Lehmann
Edge emission of n-type conducting ZnO and CdS
Solid-State Electron.
(1966)
S.E. Derenzo et al.
Temperature dependence of the fast, near-band-edge scintillation from CuI, HgI₂ PbI₂ ZnO:Ga, and CdS:In
Nucl. Instr. and Meth. A
(2002)
S.E. Derenzo, W.W. Moses, Experimental efforts and results in finding new heavy scintillators, in: F. De Notaristefani,...
C.W.E. van Eijk, New scintillators, new light sensors, new applications. in: Y. Zhiwen, F. Xiqi, L. Peijun, X. Zhilin...
W.W. Moses et al.
Cerium fluoride, a new, heavy fast scintillator
IEEE Trans. Nucl. Sci.
(1989)

There are more references available in the full text version of this article.

Cited by (244)

Study of Tl-based perovskite materials TlZX<inf>3</inf> (Z = Ge, Sn, Be, Sr; X = Cl, Br, I) for application in scintillators: DFT and TD-DFT approach
2023, Chemical Physics Impact
Scintillators are designed significantly for utilization in a broad range of technology fields, notably nuclear physics, healthcare testing, and materials analysis. A number of applications involving scintillators, such as therapeutic image analysis, burglary prevention as well and nuclear investigation, have tempted scientists to establish novel and effective scintillators. In this report, thallium-based perovskite material TlZX₃ (Z = Ge, Sn, Be, Sr; X = Cl, Br, I) has been examined by means of DFT and TD-DFT approaches. The structural, electronic, optical, and thermal properties of TlZX₃ are calculated and discussed. The HOMO-LUMO energy gap of TlGeX₃, TlSnX₃, TlBeX_3, and TlSrX₃ are found in the range of 1.76 eV to 2.12 eV, 1.77 eV to 2.27 eV, 1.56 eV to 2.04 eV and 1.06 eV to 2.81 eV, respectively. Lattice constant, unit cell volume, formation energy, VEA, electrophilicity index, polarizability, refractive index, dielectric constant, entropy, and heat capacity of TlZX₃ increase gradually from Cl to Br to I. However, HOMO-LUMO energy gap, tolerance factor, dipole moment, optical electronegativity, thermal energy, ZVPE, and Gibbs energy drop down from Cl to Br to I. Among the studied materials, TlGeI₃ shows the maximum value of molecular hardness and electronegativity while TlSrCl₃ exhibits the minimum value. The computed HOMO-LUMO energy gap and refractive index of the studied materials are in close agreement with the previously reported findings, it specifies their potential application in scintillator and solar cells.
Photoluminescence and scintillation properties of Tb-doped CaHfO<inf>3</inf> single crystals
2023, Solid State Sciences
CaHfO₃ was investigated as a promising candidate for a scintillator because of high density and large effective atomic number. Tb-doped CaHfO₃ single crystals with various Tb concentrations were synthesized by the floating zone method, and the photoluminescence (PL) and scintillation properties were investigated. All the samples showed the highest PL emission intensity at 550 nm, and the origin of this emission was identified as 4f-4f transitions of Tb³⁺ by the obtained PL decay time constants. The X-ray-induced scintillation spectra showed several emission peaks in the range of 350–650 nm, which were attributed to the 4f-4f transitions of Tb³⁺. Based on the results of the pulse height spectra, the light yield of the 1.0% Tb-doped sample was calculated to be 12,000 photons/MeV, respectively.
Optical and scintillation properties of organic–inorganic perovskite-type compounds with various hydroxyl alkyl amines or alkyl ether amines
2023, Radiation Physics and Chemistry
We evaluated photoluminescence and radiation response properties of organic–inorganic perovskite-type compounds with various hydroxyl alkyl amines or alkyl ether amines (HOC_nH_2nNH₃)₂PbCl₄ (n = 2: C2–OH, n = 3: C3–OH, n = 4: C4–OH), (CH₃CH₂OC_nH_2nNH₃)₂PbCl₄ (n = 2: 2-Ethoxy, n = 3: 3-Ethoxy), and (CH₃C₂H₄OC₃H₆NH₃)₂PbCl₄ (3-Butoxy). A clear broadband emission peak attributed to self-trapped excitons (STEs) was detected from the C2–OH, C3–OH, and 2-Ethoxy crystals under 310 nm excitation light. Additionally, they showed a fast decay time of 3.5 ns (C2–OH), 5.5 ns (C3–OH), and 3.0 ns (2-Ethoxy), which was ascribed to the recombination of STEs. In the scintillation spectra, the C2–OH, C3–OH, and 2-Ethoxy crystals exhibited a broad emission originating from the recombination to STEs. Furthermore, they exhibited a fast scintillation decay time of 2.2 ns (C2–OH), 3.5 ns (C3–OH), and 1.1 ns (2-Ethoxy) due to the recombination of STEs. Moreover, the light yield of the C3–OH crystal under alpha-ray was the highest, and the yield was estimated to be 1100 photons/5.5 MeV-α, which was higher than that of a ZnO single crystal.
Gamma radiation detector selection for CT scanner
2023, Zeitschrift fur Medizinische Physik
Three types of gamma radiation detectors associated with distributed electronics namely, NaI (Tl), HPGe and ${LaBr}_{3} (C e)$ are compared primarily focusing on electronic noise and scattering noise. Additionally, detectors of same make, material, size and electronics are also compared. A methodology is proposed to select the most suitable detector for computed tomography (CT) among the available options. Standard deviation parameter is employed to estimate electronic noise without performing CT experiment. Kanpur theorem-1(KT-1) is used to estimate the scattering noise quantitatively after verifying its sensitivity to scattering noise. The impact of scattering noise on CT profiles is evaluated using dice similarity dice coefficient. A good resemblance between KT-1 and dice coefficient is observed. A maximum difference of 56% in scattering noise is observed when five detectors used simultaneously instead of single detector whereas a discrepancy of 85% is observed between different types of radiation detectors. As far as ease of handling, operational and capital cost is concern one has to compromise minimum 12% of accuracy in CT reconstruction if NaI (Tl) detector is used with respect to best alternative available.
The proposed methodology can be applied to measurement that require minimal scattering interference data other than CT experiments. The manufacturer can add noise level of detector as a characteristic parameter in the data sheet.
Single band luminescence of Bi<sup>3+</sup> and the intensity modulation in potassium borosilicate glasses
2022, Journal of Non-Crystalline Solids
Two series of Bi-doped borosilicate glasses with compositions of different kinds and concentrations of alkali metal ions have been prepared by a melt-quenching menthod. Fluorescence spectra, lifetime, X-ray photoelectron spectroscopy (XPS) and fourier transform infrared (FTIR) spectra were done for optical characterization and structure analysis. The single band emission at around 400 nm under 290 nm and X-ray radiation were observed in the fluorescence spectras and the lifetime is 245 ns, which means the single band luminescence originated from of Bi³⁺in the borosilicate glasses. XPS and FTIR spectra show that Bi³⁺ does not convert to other valence state and the content of [BO₄] is the main factor affecting the luminescence of Bi³⁺
Development of (C<inf>6</inf>H<inf>5</inf>C<inf>2</inf>H<inf>4</inf>NH<inf>3</inf>)<inf>2</inf>Pb<inf>1-x</inf>Cd<inf>x</inf>Br<inf>4</inf> crystal scintillators with two-dimensional quantum-well structures
2021, Journal of Luminescence
Citation Excerpt :
The representative applications of scintillators are security [4,5], resource exploration [6,7], high energy physics [8–10], and medical imaging [11–13]. To detect ionizing radiations effectively and accurately, ideal scintillators need to meet the properties such as high density and large effective atomic number (Zeff) for the high X-and γ-ray sensitivity, fast luminescence decay without afterglow, and high light yield (LY) [14,15]. Scintillators are generally classified into two types based on their chemical compositions: organic and inorganic types [1].
We prepared (C₆H₅C₂H₄NH₃)₂Pb_1-xCd_xBr₄ single crystals with four different values of x (x = 0.05, 0.1, 0.25, and 0.5) and investigated their photoluminescence (PL) and scintillation properties. All the samples showed the exciton luminescence peaking at 410 and 440 nm. The x = 0.05, 0.1, 0.25, and 0.5 samples exhibited the PL quantum yields of 20.2, 24.8, 29.7, and 27.8% including the typical errors of ±2%, respectively. The X-ray-induced scintillation peaks appeared at 440 nm for all the samples, which were attributed to the exciton luminescence from the inorganic layer. The x = 0.05, 0.1, 0.25, and 0.5 samples showed the scintillation light yields of 16000, 18000, 20000, and 19000 ph/MeV including the typical errors of ±10%, respectively. In the relationship between photoabsorption peak channels and gamma-ray energies, good linearities were confirmed from 22 to 662 keV for all the samples.

View all citing articles on Scopus

View full text

Current trends in scintillator detectors and materials

Abstract

Introduction

Section snippets

Lead tungstate

Lutetium orthosilicate

Non-proportionality

Energy resolution

Scintillation from wide band-gap semiconductors

Conclusion

Acknowledgements

Nucl. Instr. and Meth. A

Nucl. Instr. and Meth. A

Nucl. Instr. and Meth. A

Nucl. Instr. and Meth. A

Solid-State Electron.

Nucl. Instr. and Meth. A

Cerium fluoride, a new, heavy fast scintillator

IEEE Trans. Nucl. Sci.