Special Issue "Scintillator Crystals: Structure, Characterization and Models for Better Performances"

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Crystalline Materials".

Deadline for manuscript submissions: closed (10 October 2019).

Special Issue Editor

Prof. Daniele Rinaldi
E-Mail Website
Guest Editor
Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Università Politecnica delle Marche, 60121 Ancona AN, Italy
Interests: scintillating crystals; crystal structure; crystal growth; crystal defects; scintillating properties; scintillating performances; models; quality control; elasto- and electro-optics; crystal characterization

Special Issue Information

Dear Colleagues,

Scintillating crystals are the primary sensitive part in radiation and particles detectors. Fundamental for high-energy physics, they are crucial in a number of fields, which span from industry to applications, such as medicine, security, geological prospections, astronomy, and aerospace. The challenges, brought by these fields, strongly stimulates scientific research on scintillators themselves and motivates the improvement of production techniques, involving scientists, technologists and crystal growers.

New crystals are proposed in addition to traditional ones. In turn, new theoretical efforts must be dedicated to reach the goals of higher light performances, energy and spatial resolution, and a fast response. At the same time, effort in the analysis and quality control of crystals is required, taking into account that improvements to quality, at the production stage, also result in cost reductions.

Nowadays, research activity is directed at co-doped crystals, organic crystals and nano-scintillators to obtain higher performances, according to the needs of different applications.

The aim of this Special Issue is to collect contributions about scintillators, involving crystal structures, performances, crystal quality, growth and production. This Special Issue is aimed at giving the reader the state-of-the-art and new achievements in scintillating crystals.

Prof. Daniele Rinaldi
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • scintillating crystals
  • crystal structure
  • crystal growth
  • crystal defects
  • scintillating properties
  • scintillating performances
  • models
  • quality control
  • elasto- and electro-optics
  • crystal characterization

Published Papers (5 papers)

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Research

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Open AccessArticle
Critical Review of Scintillating Crystals for Neutron Detection
Crystals 2019, 9(9), 480; https://doi.org/10.3390/cryst9090480 - 13 Sep 2019
Cited by 1
Abstract
There exists an ongoing need to develop and improve methods of detecting radioactive materials. As each radioactive isotope leaves a unique mark in a form of the particles it emits, new materials capable of detecting and measuring these particles are constantly sought. Neutrons [...] Read more.
There exists an ongoing need to develop and improve methods of detecting radioactive materials. As each radioactive isotope leaves a unique mark in a form of the particles it emits, new materials capable of detecting and measuring these particles are constantly sought. Neutrons and their detectors play a significant role in areas such as nuclear power generation, nuclear decommissioning and decontamination, border security, nuclear proliferation and nuclear medicine. Owing to the complexity of their detection, as well as scarcity of 3He, which has historically been the preferred choice for neutron detection in many application fields, new sensitive materials are sought. Organic and inorganic scintillating crystals have been recognised as particularly good alternatives, and as such systems that utilise them are increasingly common. As they allow investigation of the neutron energy spectra, greater information about the radioactive source can be inferred. Therefore, in this article, an extensive review of scintillating crystals used for neutron detection is presented. By describing the history of scintillating crystals and discussing changes that occurred in their use and development of methods for radiation detection, the authors present a comprehensive overview of the current situation. Supported by a practical example, possible future directions of the research area are also presented. Full article
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Open AccessArticle
Monte Carlo Optical Simulations of a Small FoV Gamma Camera. Effect of Scintillator Thicknesses and Septa Materials
Crystals 2019, 9(8), 398; https://doi.org/10.3390/cryst9080398 - 01 Aug 2019
Abstract
Optical Monte Carlo simulations have been extensively used for the accurate modeling of light transport in scintillators for the improvement of detector designs. In the present work, a GATE Monte Carlo toolkit was used to study the effect of scintillator thicknesses and septa [...] Read more.
Optical Monte Carlo simulations have been extensively used for the accurate modeling of light transport in scintillators for the improvement of detector designs. In the present work, a GATE Monte Carlo toolkit was used to study the effect of scintillator thicknesses and septa materials in the performance parameters evaluation of a commercially available small animal gamma-optical camera, named “γ-eye”. Firstly, the simulated γ-eye system was validated against experimental data. Then, part of the validated camera was modeled defining all of the optical properties by means of the UNIFIED model of GATE. Different CsI:Na scintillator crystals with varying thicknesses (from 4 mm up to 6 mm) and different reflector (septa) materials were simulated and compared in terms of sensitivity, light output and spatial resolution. Results have demonstrated the reliability of the model and indicate that the thicker crystal array presents higher sensitivity values, but degraded spatial resolution properties. Moreover, the use of black tape around crystals leads to an improvement in spatial resolution values compared to a standard white reflector material. Full article
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Open AccessArticle
Decay Time Estimates by a Continuum Model for Inorganic Scintillators
Crystals 2019, 9(1), 41; https://doi.org/10.3390/cryst9010041 - 15 Jan 2019
Cited by 1
Abstract
We use the phenomenological continuum model for inorganic scintillators proposed by the author to give decay time estimates for four scintillators previously studied, namely NaI:Tl, CaF2, Gd2SiO5Ce (GSO:Ce), and LaCl3:Ce. We show that, in order [...] Read more.
We use the phenomenological continuum model for inorganic scintillators proposed by the author to give decay time estimates for four scintillators previously studied, namely NaI:Tl, CaF2, Gd2SiO5Ce (GSO:Ce), and LaCl3:Ce. We show that, in order to obtain a good estimate of the decay time, we need to know (besides other well-known parameters) either the excitation carriers’ mobility or the structure and the parameters of the recombination mechanism. For these four materials, we know the data for the recombination term, whereas we have very scarce information about mobilities. However, we show that also in absence of experimentally-measured mobilities, with reasonable assumptions about them, we can obtain a good estimate for the slow component of the decay time. We show also when it is appropriate to model scintillation with one of the two most-used phenomenological models, the kinetic and the diffusive. The main point of the present approach is that it requires a limited set of experimentally-measured data and can be hopefully used in conjunction with more sophisticated and detailed models to design faster inorganic scintillators. Full article

Review

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Open AccessReview
Quality Control and Structural Assessment of Anisotropic Scintillating Crystals
Crystals 2019, 9(7), 376; https://doi.org/10.3390/cryst9070376 - 23 Jul 2019
Abstract
Nowadays, radiation detectors based on scintillating crystals are used in many different fields of science like medicine, aerospace, high-energy physics, and security. The scintillating crystals are the core elements of these devices; by converting high-energy radiation into visible photons, they produce optical signals [...] Read more.
Nowadays, radiation detectors based on scintillating crystals are used in many different fields of science like medicine, aerospace, high-energy physics, and security. The scintillating crystals are the core elements of these devices; by converting high-energy radiation into visible photons, they produce optical signals that can be detected and analyzed. Structural and surface conditions, defects, and residual stress states play a crucial role in their operating performance in terms of light production, transport, and extraction. Industrial production of such crystalline materials is a complex process that requires sensing, in-line and off-line, for material characterization and process control to properly tune the production parameters. Indeed, the scintillators’ quality must be accurately assessed during their manufacture in order to prevent malfunction and failures at each level of the chain, optimizing the production and utilization costs. This paper presents an overview of the techniques used, at various stages, across the crystal production process, to assess the quality and structural condition of anisotropic scintillating crystals. Different inspection techniques (XRD, SEM, EDX, and TEM) and the non-invasive photoelasticity-based methods for residual stress detection, such as laser conoscopy and sphenoscopy, are presented. The use of XRD, SEM, EDX, and TEM analytical methods offers detailed structural and morphological information. Conoscopy and sphenoscopy offer the advantages of fast and non-invasive measurement suitable for the inspection of the whole crystal quality. These techniques, based on different measurement methods and models, provide different information that can be cross-correlated to obtain a complete characterization of the scintillating crystals. Inspection methods will be analyzed and compared to the present state of the art. Full article
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Open AccessReview
Inorganic, Organic, and Perovskite Halides with Nanotechnology for High–Light Yield X- and γ-ray Scintillators
Crystals 2019, 9(2), 88; https://doi.org/10.3390/cryst9020088 - 08 Feb 2019
Cited by 4
Abstract
Trends in scintillators that are used in many applications, such as medical imaging, security, oil-logging, high energy physics and non-destructive inspections are reviewed. First, we address traditional inorganic and organic scintillators with respect of limitation in the scintillation light yields and lifetimes. The [...] Read more.
Trends in scintillators that are used in many applications, such as medical imaging, security, oil-logging, high energy physics and non-destructive inspections are reviewed. First, we address traditional inorganic and organic scintillators with respect of limitation in the scintillation light yields and lifetimes. The combination of high–light yield and fast response can be found in Ce 3 + , Pr 3 + and Nd 3 + lanthanide-doped scintillators while the maximum light yield conversion of 100,000 photons/MeV can be found in Eu 3 + doped SrI 2 . However, the fabrication of those lanthanide-doped scintillators is inefficient and expensive as it requires high-temperature furnaces. A self-grown single crystal using solution processes is already introduced in perovskite photovoltaic technology and it can be the key for low-cost scintillators. A novel class of materials in scintillation includes lead halide perovskites. These materials were explored decades ago due to the large X-ray absorption cross section. However, lately lead halide perovskites have become a focus of interest due to recently reported very high photoluminescence quantum yield and light yield conversion at low temperatures. In principle, 150,000–300,000 photons/MeV light yields can be proportional to the small energy bandgap of these materials, which is below 2 eV. Finally, we discuss the extraction efficiency improvements through the fabrication of the nanostructure in scintillators, which can be implemented in perovskite materials. The recent technology involving quantum dots and nanocrystals may also improve light conversion in perovskite scintillators. Full article
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