A new method for spectral shape discrimination (SSD) of fast neutrons and gamma rays has been investigated. Gammas interfere with neutron detection, making efficient discrimination necessary for practical applications. Pulse shape discrimination (PSD) in liquid organic scintillators is currently the most effective means of gamma rejection. The hazardous liquids, restrictions on volume, and the need for fast timing are drawbacks to traditional PSD scintillators. In this project we investigated harvesting excited triplet states to increase scintillation yield and provide distinct spectral signatures for gammas and neutrons. Our novel approach relies on metal-organic phosphors to convert a portion of the energy normally lost to the scintillation process into useful luminescence with sub-microsecond lifetimes. The approach enables independent control over delayed luminescence wavelength, intensity, and timing for the first time. We demonstrated that organic scintillators, including plastics, nanoporous framework materials, and oil-based liquids can be engineered for both PSD and SSD.

This thesis evaluated the potential of neutron-capture gamma rays in elemental analysis. A large portion of the work was devoted to the development of a method for the analysis of weak peaks in gamma ray spectra. This was based on equations developed for the standard deviation in the measurement of the various peak parameters, consideration being also given to the reduction in the statistical fluctuations obtained by smoothing the data with the use of Fourier transforms. Two methods of peak area determination were considered end their relative effectiveness examined. An equation was then derived for the minimum weight of an element needed for reliable quantitative analysis. The equations were verified using both real and pseudo-experimental data constructed with the use of a computer. Experiments were carried out using the MIT Reactor with samples positioned La) in a high neutron flux next to the reactor tank (2xl01- n/sq.cm sec), and (b) in an external neutron beam facility of relatively lower but well thermalized flux (2xl0 n/sq.cm sec). Capture gamma ray spectra were obtained with a three-crystal system capable of operating in the free mode, the Compton suppression mode and as a pair spectrometer. The results were used to examine the relative analytical sensitivity of the internal and external sample arrangements and the various gamma detection modes. The minimum measurable weights of 75 elements were evaluated for a stainless steel sample. For these computations use was made of the listing of capture gamma ray spectra recently established by the MIT gamma spectroscopy group. 'In a majority of the cases the detection limits range between 0.1 percent and 10 percent. Equations were developed for extending the results to different samples and different. experimental arrangements.

The Theory and Practice of Scintillation Counting is a comprehensive account of the theory and practice of scintillation counting. This text covers the study of the scintillation process, which is concerned with the interactions of radiation and matter; the design of the scintillation counter; and the wide range of applications of scintillation counters in pure and applied science. The book is easy to read despite the complex nature of the subject it attempts to discuss. It is organized such that the first five chapters illustrate the fundamental concepts of scintillation counting. Chapters 6 to 10 detail the properties and applications of organic scintillators, while the next four chapters discuss inorganic scintillators. The last two chapters provide a review of some outstanding problems and a postscript. Nuclear physicists, radiation technologists, and postgraduate students of nuclear physics will find the book a good reference material.

The handbook centers on detection techniques in the field of particle physics, medical imaging and related subjects. It is structured into three parts. The first one is dealing with basic ideas of particle detectors, followed by applications of these devices in high energy physics and other fields. In the last part the large field of medical imaging using similar detection techniques is described. The different chapters of the book are written by world experts in their field. Clear instructions on the detection techniques and principles in terms of relevant operation parameters for scientists and graduate students are given.Detailed tables and diagrams will make this a very useful handbook for the application of these techniques in many different fields like physics, medicine, biology and other areas of natural science.

This book introduces the physics and chemistry of plastic scintillators (fluorescent polymers) that are able to emit light when exposed to ionizing radiation, discussing their chemical modification in the early 1950s and 1960s, as well as the renewed upsurge in interest in the 21st century. The book presents contributions from various researchers on broad aspects of plastic scintillators, from physics, chemistry, materials science and applications, covering topics such as the chemical nature of the polymer and/or the fluorophores, modification of the photophysical properties (decay time, emission wavelength) and loading of additives to make the material more sensitive to, e.g., fast neutrons, thermal neutrons or gamma rays. It also describes the benefits of recent technological advances for plastic scintillators, such as nanomaterials and quantum dots, which allow features that were previously not achievable with regular organic molecules or organometallics.

"Radiation detection is key to experimental nuclear physics as well as underpinning a wide range of applications in nuclear decommissioning, homeland security and medical imaging. This book presents the state-of-the-art in radiation detection of light and heavy ions, beta particles, gamma rays and neutrons. The underpinning physics of different detector technologies is presented, and their performance is compared and contrasted. Detector technology likely to be encountered in contemporary international laboratories is also emphasized. There is a strong focus on experimental design and mapping detector technology to the needs of a particular measurement problem. This book will be invaluable to PhD students in experimental nuclear physics and nuclear technology, as well as undergraduate students encountering projects based on radiation detection for the first time. Part of IOP Series in Nuclear Spectroscopy and Nuclear Structure." -- Prové de l'editor.