Physical Processes In Inorganic Scintillators

During the last ten to fifteen years, researchers have made considerable progress in the study of inorganic scintillators. New scintillation materials have been investigated, novel scintillation mechanisms have been discovered, and additional scintillator applications have appeared. Demand continues for new and improved scintillation materials for a variety of applications including nuclear and high energy physics, astrophysics, medical imaging, geophysical exploration, radiation detection, and many other fields. However, until now there have been no books available that address in detail the complex scintillation processes associated with these new developments. Now, a world leader in the theory and applications of scintillation processes integrates the latest scientific advances of scintillation into a new work, Physical Processes in Inorganic Scintillators. Written by distinguished researcher Piotr Rodnyi, this volume explores this challenging subject, explains the complexities of scintillation from a modern point of view, and illuminates the way to the development of better scintillation materials. This unique work first defines the fundamental physical processes underlying scintillation and governing the primary scintillation characteristics of light output, decay time, emission spectrum, and radiation hardness. The book then discusses the complicated mechanisms of energy conversion and transformation in inorganic scintillators. The section on the role of defects in energy transfer and scintillation efficiency will be of special interest. Throughout, the author does not offer complicated derivations of equations but, instead, presents useful equations with practical results.

This second edition features new chapters highlighting advances in our understanding of the behavior and properties of scintillators, and the discovery of new families of materials with light yield and excellent energy resolution very close to the theoretical limit. The book focuses on the discovery of next-generation scintillation materials and on a deeper understanding of fundamental processes. Such novel materials with high light yield as well as significant advances in crystal engineering offer exciting new perspectives. Most promising is the application of scintillators for precise time tagging of events, at the level of 100 ps or higher, heralding a new era in medical applications and particle physics. Since the discovery of the Higgs Boson with a clear signature in the lead tungstate scintillating blocks of the CMS Electromagnetic Calorimeter detector, the current trend in particle physics is toward very high luminosity colliders, in which timing performance will ultimately be essential to mitigating pile-up problems. New and extremely fast light production mechanisms based on Hot-Intraband-Luminescence as well as quantum confinement are exploited for this purpose. Breakthroughs such as crystal engineering by means of co-doping procedures and selection of cations with small nuclear fragmentation cross-sections will also pave the way for the development of more advanced and radiation-hard materials. Similar innovations are expected in medical imaging, nuclear physics ecology, homeland security, space instrumentation and industrial applications. This second edition also reviews modern trends in our understanding and the engineering of scintillation materials. Readers will find new and updated references and information, as well as new concepts and inspirations to implement in their own research and engineering endeavors.

Radiation scintillation detectors are used in numerous fields including low and high energy physics (HEP) experiments, medical imaging (MI), space exploration, well-logging, and homeland security. Since they can be manufactured with vastly different properties for virtually any type of radiation detection application, they are ubiquitous in scientific research and industry. For a given application, scintillation detectors are chosen based on their properties such as their efficiency, energy resolution (ER), and time resolution. Light yield (LY) is one of the most important properties of scintillators in characterizing their performance under irradiation. It has a direct correlation with the energy and time resolutions of scintillators since a larger number of light photons produced in scintillators translates to a larger number of light photons detected by photosensors, which improves both energy and time resolutions. Excellent energy and time resolutions of scintillators are critical in various applications such as radioisotope identification and positron emission tomography - time of flight (PET-TOF). LY is also an important parameter in simulation studies where the goal is to either characterize already existing detectors and compare simulation results to experimental observations or investigate novel configurations involving scintillators. In the latter case, LY plays a critical role in the optimization of new detection systems. Although the importance of LY is well known in the field of radiation detection, its accurate measurement is not straightforward. Any measurement of LY is bound to have large uncertainties due to various physical processes involved in its estimation. Accurate measurement of scintillator LYs necessitates accurate knowledge of numerous properties of both the scintillators and the photosensors that are used to convert the scintillation light into electronic signal. These properties include but not limited to the surface conditions and bulk properties of scintillators, the photodetection efficiency of photosensors, the single-photoelectron response (SPER) of photosensors and the light reflection properties between scintillators and photosensors. Consequently, there are large differences in reported LY values even for widely used scintillators such as thallium-activated sodium-iodide (NaI(Tl)) and cerium-activated lutetium-yttrium oxyorthosilicate (LYSO:Ce3+), as any major change in the aforementioned quantities has an impact on the estimated LY. One of the approaches to determine the scintillator LYs is to measure their light outputs (LO) as a function of scintillator thickness and fit an analytical model function to the data set to extrapolate the LO for a point scintillator. Since this method does not require relatively sophisticated equipment such as integrating spheres, electron monochromators or electron collimators, it can be carried out in most radiation detection laboratories. However, the model functions need to be as realistic as possible, and they need to contain all the relevant physics to make LY estimations accurate. In this thesis, two new analytical light transport model (LTM) functions for cuboid scintillators are derived, and it is demonstrated that they make LY estimations more accurate. These two analytical LTM functions are called the extended 2D-model and the 3D-model. The 3D-model is shown to estimate the LO of scintillators as accurately as Monte Carlo (MC) simulations, which makes full-scale MC simulations in cuboid scintillators needless in certain applications. One of the most important quantities that affect LY estimations is the scintillator-photosensor interface reflection coefficient (SPIRC). SPIRC is the observed reflection coefficient of the scintillator-photosensor boundary averaged over photon angles and energies and is typically considered a constant. Since scintillation emission contains photons of various wavelengths, and scintillators have wavelength dependent surface and bulk properties, it is not straightforward to reliably estimate SPIRCs. Moreover, SPIRC is dependent on the optical coupling methods employed in radiation measurements, which are typically dry (air) coupling and grease coupling. In this thesis, two new experimental methods (the single-PMT setup and the dual-PMT setup) are suggested and tested to estimate the SPIRCs in different optical coupling configurations. Furthermore, a new hypothesis is put forward regarding the SPIRC dependency on scintillator thickness. It is hypothesized through MC simulations that SPIRC decreases with increasing scintillator thickness as a result of change in the scintillation photons' angular distribution on the scintillator-photosensor interface (SPI). This hypothesis is tested with three different inorganic scintillation crystals by employing the two new experimental methods, and the SPIRC dependency on scintillator thickness is experimentally observed by evaluating the extended 2D-model and the 3D-model for LYSO:Ce3+ and cerium-activated gadolinium-aluminum-gallium garnet (GAGG:Ce3+) inorganic scintillators. The SPIRC dependency on scintillator thickness is observed by the 3D-model with more than 2[sigma] confidence for both LYSO:Ce3+ and GAGG:Ce3+ scintillators in the single-PMT setup. The SPIRC dependency on scintillator thickness is observed with more than 3[sigma] confidence for GAGG:Ce3+ scintillators in the dual-PMT setup. Consequently, it is suggested that the measurements should consider thickness-dependent SPIRCs (TD-SPIRC) to make accurate LY estimations.

​ This book will serve as the definitive source of detailed information on radiation, ionization, and detection in nuclear medicine. It opens by considering fundamental aspects of nuclear radiation, including dose and energy, sources, and shielding. Subsequent chapters cover the full range of relevant topics, including the detection and measurement of radiation exposure (with detailed information on mathematical modelling); medical imaging; the different types of radiation detector and their working principles; basic principles of and experimental techniques for deposition of scintillating materials; device fabrication; the optical and electrical behaviors of radiation detectors; and the instrumentation used in nuclear medicine and its application. The book will be an invaluable source of information for academia, industry, practitioners, and researchers.

This book presents the current advances in understanding of the fast excitation transfer processes in inorganic scintillation materials, the discovery of new materials exhibiting excellent time resolution, and the results on the evaluation of timing limits for scintillation detectors. The book considers in-depth basic principles of primary processes in energy relaxation, which play a key role in creating scintillating centers to meet a growing demand for knowledge to develop new materials combining high energy and time resolutions. The rate of relaxation varies. However, the goal is to make it extremely fast, occurring within the ps domain or even shorter. The book focuses on fast processes in scintillation materials. This approach enables in-depth understanding of fundamental processes in scintillation and supports the efforts to push the time resolution of scintillation detectors towards 10 ps target. Sophisticated theoretical and advanced experimental research conducted in the last decade is reviewed. Engineering and control of the energy transfer processes in the scintillation materials are addressed. The new era in development of instrumentation for detection of ionizing radiation in high- energy physics experiments, medical imaging and industrial applications is introduced. This book reviews modern trends in the description of the scintillation build up processes in inorganic materials, transient phenomena, and engineering of the scintillation properties. It also provides reliable background of scientific and educational information to stimulate new ideas for readers to implement in their research and engineering. The book is aimed at providing a coherent updated background of scientific and instructive information to stimulate new ideas for readers in their research and engineering.

PET and SPECT are two of today’s most important medical-imaging methods, providing images that reveal subtle information about physiological processes in humans and animals. Emission Tomography: The Fundamentals of PET and SPECT explains the physics and engineering principles of these important functional-imaging methods. The technology of emission tomography is covered in detail, including historical origins, scientific and mathematical foundations, imaging systems and their components, image reconstruction and analysis, simulation techniques, and clinical and laboratory applications. The book describes the state of the art of emission tomography, including all facets of conventional SPECT and PET, as well as contemporary topics such as iterative image reconstruction, small-animal imaging, and PET/CT systems. This book is intended as a textbook and reference resource for graduate students, researchers, medical physicists, biomedical engineers, and professional engineers and physicists in the medical-imaging industry. Thorough tutorials of fundamental and advanced topics are presented by dozens of the leading researchers in PET and SPECT. SPECT has long been a mainstay of clinical imaging, and PET is now one of the world’s fastest growing medical imaging techniques, owing to its dramatic contributions to cancer imaging and other applications. Emission Tomography: The Fundamentals of PET and SPECT is an essential resource for understanding the technology of SPECT and PET, the most widely used forms of molecular imaging. *Contains thorough tutorial treatments, coupled with coverage of advanced topics *Three of the four holders of the prestigious Institute of Electrical and Electronics Engineers Medical Imaging Scientist Award are chapter contributors *Include color artwork

Comprehensive Biomedical Physics, Ten Volume Set is a new reference work that provides the first point of entry to the literature for all scientists interested in biomedical physics. It is of particularly use for graduate and postgraduate students in the areas of medical biophysics. This Work is indispensable to all serious readers in this interdisciplinary area where physics is applied in medicine and biology. Written by leading scientists who have evaluated and summarized the most important methods, principles, technologies and data within the field, Comprehensive Biomedical Physics is a vital addition to the reference libraries of those working within the areas of medical imaging, radiation sources, detectors, biology, safety and therapy, physiology, and pharmacology as well as in the treatment of different clinical conditions and bioinformatics. This Work will be valuable to students working in all aspect of medical biophysics, including medical imaging and biomedical radiation science and therapy, physiology, pharmacology and treatment of clinical conditions and bioinformatics. The most comprehensive work on biomedical physics ever published Covers one of the fastest growing areas in the physical sciences, including interdisciplinary areas ranging from advanced nuclear physics and quantum mechanics through mathematics to molecular biology and medicine Contains 1800 illustrations, all in full color