Mossbauer scattering studies with the isotopes Os186, Os188, Eu153 and Pr1410

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Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date

2011

Author dc:creator

• Morrison, Rollin John

Contributors dc:contributor

• Frauenfelder, Hans

• Eu153
• Pr141
• Mossbauer scattering
• gamma rays
• recoil energy
• scattering geometry
• Isotopes
• Os186
• Os188

Statement dc:rights

• 1965 Rollin John Morrison

Language dc:language

en

Identifier

The thesis describes the observation of sizable Mossbauer effects with gamma rays of energies up to 155 keV. In order to observe significant effects for transitions with large recoil energies, and therefore small recoilless fractions, the eXperiments were performed with a scattering geometry. Some theoretical aspects of Mossbauer scattering are discUssed.. Call. oulations of the rec9illes and nonrecoilless scattered intensities tor single line Lorentzian distributions are presented. The scattered intensities are expressed in terms of a scattering ,function which contains the parameters of the scatterer. The scattering function has been evaluated for a wide range of values of the recoilless fraction. electronic absorption. thickness, and line width of the scatterer. The attractiveness and general applicabillty o£ the scattering method. are demonstrated by the experimental results. The effects observed for the various sources and scatterers are given in the table below. These measurements were made w:i.th source and scatterer temperatures below 35 K. The products of the source and scatterer recoilless fractions have been determined from the scattered intensities with the aid of the calculated scattering function. With the assumption that the source and scatterer Debye temperatures ~D were equal. values theta = (312 ± 7)0 K and theta = (322 ± 7)0 K were determined from the scattered intensities for the Os186 and Os188 measurements. experients were performed with higher source and scatterer temperatures. From these measurements we found that 2 the etfective Debye temperature increases with temperature and with the mag~tude of the reoQ1l energy. Recoilless fractions and Debye temperatures were calculated for all.of the measurements. Ferrimagnetio europium ~ron garnet'was al$o used a,s a scatterer for the 10~kev transition of Eu1.5~ From the magnetic hyperfine pattern observed, the ratio of the excited state and ground state g factors was determined. Using a previously measured value tor the ground state magnetic moment we found the value mu = (1.9± 0.2) n m for the magnetic moment of the excited state.
6192561

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/23976