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Title:Dynamic proton polarization in some rare earth ethyl sulphates
Author(s):Wollan, David Strand
Doctoral Committee Chair(s):Stapleton, H.J.
Department / Program:Physics
Discipline:Physics
Degree:Ph.D.
Genre:Dissertation
Subject(s):dynamic polarization of protons
solid state effect
liquid helium
rare earth ethyl sulphates
Abstract:Measurements of the dynamic polarization of protons by the solid state effect ("ef£et solide") have been made at liquid helium temperatures on single crystals of erbium-doped and neodymium-doped yttrium ethyl sulphate ( (Er, Y)ES and (Nd, Y)ES). T he dynamic polarization was induced by saturating the forbidden, satellite electron spin resonance (ESR) line of the paramagnetic ion, and was measured by comparing proton nuclear magnetic resonance (NMR) signals. Becau.se of its higher hydrogen density, it was hoped that YES might be a better material than the commonly-used lanthanum magnesium nitrate (LaMN) for use as a polarized proton target for nuclear scattering experiments. Preliminary results on (Er, Y)ES at 9.5 Gc/sec showed several features that prohibit high proton polarizations. An anomalous behavior was observed in o 167 (Er, Y)E,:S at 2.0 K du~ to the overlap of one of the Er hyperfine lines with the main ESR transition, Preliminary experiments on (Nd, Y)ES at 9.5 Gc / sec indicated that this system was favorable for high polarizations. o Measqrements on (Nd, Y)ES at 69.5 Gc/sec, 16,200 Oe and 2.1 K gave a maximum proton polarization of 0.215, as compared with the ideal polarization of 0.66 expected under these conditions. The measured polarizations in this latter case were concentration independent for paramagnetic dopings from 0.25% to 2%. These results are in disagreement with Jeffries' "shell-of-influence" model and Borghini's density matrix theory of the solid state effect. Over 90% of the YES crystals o . cracked when cooled to 4.2 K. Because of thls and the low proton polarizations attained, (Nd, Y)ES is not recommended as a polarized proton target material for nuclear scattering experiments. Nonexponential proton NMR relaxation decays were observed in (Nd, Y)ES at 16,200 Oe and liquid helium temperatures.
Issue Date:1966
Genre:Dissertation / Thesis
Type:Text
Language:English
URI:http://hdl.handle.net/2142/25080
Rights Information:1966 David Strand Wollan
Date Available in IDEALS:2011-05-31
Identifier in Online Catalog:6120743


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