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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.