Download or read book Positron Annihilation Lifetime Spectroscopy Studies of Lead Zirconium Titanate and Strontium Titanate written by Sudhi Singh and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Positron Annihilation Energy and Lifetime Spectroscopy Studies on Radiation Damaged Stainless Steel 316L and Steel 9Cr1Mo written by Lali Tchelidze and published by . This book was released on 2005 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Positron Annihilation ICPA 9 written by Zs. Kajcsos and published by Trans Tech Publications Ltd. This book was released on 1992-01-01 with total page 2146 pages. Available in PDF, EPUB and Kindle. Book excerpt: The volumes present over 400 reviewed papers on the present state of the art and future prospects in the wide field of research involving positrons. The foreword by Edward Teller and the summaries by Jean-Charles Abbe (Chemistry) and Alfred Seeger (Physics) demonstrate how the field is seen from "outside" and from "inside".
Download or read book Positron Annihilation ICPA 10 written by Yuan Jin He and published by Trans Tech Publications Ltd. This book was released on 1994-11-24 with total page 1104 pages. Available in PDF, EPUB and Kindle. Book excerpt: Positron Annihilation - ICPA-10 presents new results and ideas of researchers who seek more profound understanding of the nature of positron annihilation. All these scientific and technological thoughts are included in these two-volume proceedings, which contain 7 review talks, 203 contributed papers (among them, 20 are invited), and 3 summary talks. The volume is complete with keyword and author indices.
Download or read book Positron Annihilation Lifetime Spectroscopy written by Yang Yu and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Positron annihilation lifetime spectroscopy (PALS); Free volume; Polymers; Amorphous; Crystalline; Semicrystalline; Ionic liquids
Download or read book Chemical Preparation and Composition Analysis of Strontium Doped Lead Zirconate Titanate written by Chutimon Ratanapeanchai and published by . This book was released on 1998 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Positron Annihilation Studies of Very Fine Structured Materials written by Phillip L. Jones and published by . This book was released on 1985 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: UAn Fe-Nd-B permanent magnet alloy (Crumax 30) has been evaluated as a function of thermal treatment by means of positron annihilation lifetime spectroscopy. The results of this preliminary study indicate that the room temperature lifetime spectra can be accurately modeled using either a two-component or a partially constrained three-component fit. The thermally-induced variations in lifetime spectra can be correlated with the concomitant decrease in magnetic coercivity in a manner that is consistent with thermally-induced microstructural transformations reported in the literature. The demonstrated sensitivity of positron annihilation lifetime spectroscopy to thermally-induced changes in both microstructure and magnetic coercivity suggests that a more thorough systematic positron annihilation evaluation of Fe-R-B alloys could provide further insight into the relationship between processing, structure and magnetic properties.
Download or read book Design and Performance Analysis of an Ultra fast Digital Positron Annihilation Lifetime Spectrometer at The Ohio State University written by James Patrick Ralston and published by . This book was released on 2013 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Positron Annihilation Lifetime Spectroscopy (PALS) is a highly effective technique to quantify the lattice deformation in solid materials. The technique is based on amount of time it takes a free neutron to annihilate in the sample material. Since the timescales of positron lifetime are on the order of a nanosecond, high precision timing measurements are required to obtain useful measurements. Recent innovations in digital data acquisition technology has allowed digital systems to approach and surpass the timing capabilities of their analog counterparts. Digital acquisition systems also have the advantage of a generally simpler setup that offers equal capabilities at a lower cost. The digital system can potentially offer double the counting rates, as each detector in the system can measure both starting and stopping events. The spectrometer designed allows for high performance timing measurements, equal and better than analog and more expensive digital systems. Custom software, developed in C++/C, has been written for the data analysis and data acquisition and allows for very high counting rates. The system hardware was assembled with an ORTEC 905-21 fast plastic scintillation detector and a CAEN N6751 2 GS/s digitizer, the timing performance of the specific hardware combination used has been previously undetermined. The timing performance analysis was conducted with using a Co-60 button sized radiation source to measure coincident gamma rays. Since the gamma rays are emitted from the source at almost the exact same moment, the measured time difference between detected events can be used to measure the uncertainty in the timing of the spectrometer. The timing resolution of the spectrometer is characterized by the Full Width at Half Maximum (FWHM) of the measured Co-60 spectra. The measured value of the FWHM of the spectrometer was 208.5 ± 1.1 ps.
Download or read book Positron Annihilation Lifetime Studies of Deformed and Shock Loaded Tantalum written by and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shock loading and quasi-static loading has been examined in annealed high purity tantalum. Investigation with positron annihilation lifetime spectroscopy, microhardness testing and optical microscopy shows increased dislocation density with increased true strain, but no significant increases with increased strain rate, aside from small degrees of dynamic recovery and twinning observed in shock loaded sample. The authors conclude that these results support the theory that deformation in tantalum is controlled by dislocation drag above the Peierls stress and that strain rate effects, which are dearly observed in most other materials, are suppressed. Quench hardening in annealed high purity tantalum has also been investigated. Microhardness testing results show quench hardening alter quenching from temperatures above 1100 deg C with cooling rates of approximately 200 deg C/min; these observations appear to be consistent with vacancy clustering. However, the temperatures required to produce quench hardening exceed the maximum estimates of temperatures achieved during shock loading. The authors conclude that quench hardening is not expected to have any significant effect on shock loading in tantalum.
Download or read book La D pendance Vis vis de la Temp rature de L annihilation Des Positrons Dans L alpha Hf written by G. M. Hood and published by Chalk River, Ont. : Chalk River Laboratories, Reactor Materials Research Branch. This book was released on 1994 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Construction and Testing of a Positron Annihilation Lifetime Spectrometer written by Brian M. Wieland and published by . This book was released on 2012 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Positron Annihilation Lifetime Spectroscopy (PALS) is a nuclear technique that was developed in the 1970s as a method to assess defects in materials. This technique has tremendous potential as a powerful tool for non-destructive quantification of the types and densities of defects within solids. Following the injection of positrons into a solid material, the positrons pair-annihilate at a rate dependent upon the density of electrons near the injection site. If there are lattice vacancies or dislocation defects near the injection site, the positrons are attracted to these areas, which have lower electron densities and thus give rise to longer positron lifetimes. Typical positron lifetimes in defect-free conductor-type metals are -'-'1OO ps, while lifetimes within defect regions are 2OO ps. In order to discern between these minute lifetime differences, a spectrometer with very good timing resolution has been constructed and optimized. The capabilities of the spectrometer have been tested using a 22Na positron emitter by performing source-based measurements of positron lifetimes in high-purity samples of aluminum, nickel, copper, and lead. Test results are in excellent agreement with currently accepted literature values, thus validating the apparatus and data analysis technique. This study is an important first step towards the development of a modern positron annihilation lifetime spectrometer for use in accelerator-based, gamma-induced positron annihilation spectroscopy (AG-PAS).
Download or read book Positron Annihilation Studies of Solids and Surfaces written by Paul Richard Guagliardo and published by . This book was released on 2011 with total page 255 pages. Available in PDF, EPUB and Kindle. Book excerpt: [Truncated abstract] This thesis describes the first positron annihilation studies undertaken in the Atomic, Molecular and Surface Physics group in the School of Physics at the University of Western Australia (UWA). We have studied a range of systems with differing positron annihilation characteristics with the aim of characterising their defect properties, and in the process have gained insight into the interactions of positrons and positronium with materials. The project started with establishing a positron annihilation laboratory. This entailed developing procedures to produce and safely handle sealed 22Na sources, and testing positron annihilation instrumentation and experimental methods. The project evolved through collaboration with physicists, engineers, chemists, materials scientists, metallurgists and medical scientists and through a number of interesting experimental explorations of the physical phenomena affecting positron annihilation. An overview of these investigations and a thesis synopsis is given below. Chapter 1 is an introduction to positron annihilation techniques, concentrating on the interactions of positrons (and positronium) with materials, and on the spectroscopies that exploit the annihilation processes for the purpose of studying condensed matter systems. Chapter 2 describes the testing and optimisation of the positron annihilation lifetime spectrometer and Doppler broadening spectrometer. In Chapter 3, positron annihilation has been applied to study cation vacancies in oxides that exhibit ionic bonding. Such vacancies have a relative negative charge and so attract positrons, and the relatively low electron density at these sites causes enhanced positron lifetimes. Oxides considered in this work are (a) rutile, (Ti,Nb)O2, sintered in air and Ar; (b) tin oxide, (Sn,Nb)O2 sintered in air; (c) monoclinic zirconia, (Zr,Nb)O2; (d) pollucite, Cs(1-x)Al(1-x)Si(2+x)O6 and (e) Ta- and Ti-doped Zn2TiO4. All systems except (c) showed enhanced lifetimes when doping or off-stoichiometry was increased. In Chapter 4, positron annihilation has been used to study the nanoporosity of cementitious materials. The mechanical properties of these materials are heavily influenced by porosity, with the volume and size distribution of pores controlling both the strength and durability of the material...
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1973 with total page 1256 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Piezoelectric Ceramics written by and published by . This book was released on 1996 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2364 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Radiation and Health written by Thormod Henriksen and published by CRC Press. This book was released on 2002-09-05 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radiation and the effects of radioactivity have been known for more than 100 years. International research spanning this period has yielded a great deal of information about radiation and its biological effects and this activity has resulted in the discovery of many applications in medicine and industry including cancer therapy, medical diagnostics
Download or read book Toxicology written by D. Nicholas Bateman and published by . This book was released on 2014 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: Overdose and poisoning are one of the most frequent acute medical presentations seen in emergency departments, and high dependency and intensive care facilities. The Oxford Desk Reference: Toxicology provides an authoritative guide for the management of patients with poisoning. Each chapter includes key clinical features and potential treatment options to help physicians to assess the potential severity of the poisoned patient and provide the optimum clinical care. A reader-friendly layout ensures that information is easy to find and assimilate, and topics are self-contained to aid quick diagnosis. Presented in an easy-to-use double-page spread format, highly bulleted and concise, the Oxford Desk Reference: Toxicology is ideal for quick referral when an acute problem arises. Contributions from the leading figures in toxicology make this book indispensable for all those involved with the management of poisoned patients, especially trainees and consultants working in emergency medicine, acute medicine, and critical care.
