Research Group Data Archive, 1985-2018

Abstract

Included here are two parallel archives, one of raw spectral DATA and the other of spectral ANALYSIS. There is a small number of other spectra, such as of positron lifetimes, x-ray diffractograms,

“DATA” contains raw data in the form of spectra measured as a function of delayed coincidence time (PAC) or velocity shift (Mössbauer effect) due to source motion. There is a small number of other kinds of spectra, including positron lifetimes, x-ray diffractograms, etc. This archive is mostly organized in folders by the principal solid-state phase under study, such as “Ni” for nickel metal, or “Al3Ni” for the intermetallic compound. All samples of “Al3Ni” studied will have raw data in the same folder. Each data file is identified by a date-code of the day in which the spectrum was saved. Thus, for example, 070418q.raw identifies a spectrum saved on April 18, 2007. For PAC spectra, there were two spectrometers, PAC1 and PAC2. Files saved on PAC1 had letters "a", "b", "c"... appended to identify if it was the first, second... file saved on that day. Similarly, files saved on PAC2 were tagged with letters "p", "q", "r"... Thus, file 070418q.raw was the second file saved on PAC2 on April 18, 2007. Data files originated on a DEC 3000 Alpha workstation, running under the time-sharing operating system VMS. VMS automatically appends version numbers at the ends of file extension names so that, for example, 070418p.raw;3 is version 3 of file 070418p.raw. These version numbers have not been removed. It is believed that all, or nearly all, files in the DATA archive are alphanumeric.

“ANALYSIS” contains scans of results of spectral fits, mostly with images of the fitted spectra and parameters fitted by the least mean-squares method, often with values of the reduced Chi2 for the fit that, for good data and an appropriate fitting function, should be a number close to 1.0. All fitting programs were written by Collins. Results of the fits were scanned, with separate folders for each phase, such as “Al3Ni”, and separate pdf files for each sample studied. For example, folder “Al3Ni” has five subfolders: “Al3Ni-23%Ni.pdf”, “Al3Ni-23.15%Ni.pdf”, “Al3Ni-25.36%Ni.pdf”, etc. Generally, each sample was studied as a function of temperature, or after a series of isochronal annealings, with results of all runs for a sample contained within the same pdf file.