Berlin, Techn. Univ., Diss., 2004. / Computerdatei im Fernzugriff.

Thesis (Ph. D.)--University of Wisconsin--Madison,1983. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 123-128).

Hannover, Universiẗat, Diss., 2000.

Düsseldorf, Universiẗat, Diss., 2001.

A study has been made of the fast neutron induced reactions in natural neon gas. The neon was contained in a cylindrical geometry fast gridded ionization chamber, and the irradiating monokinetic neutrons were obtained by bombarding thin heavy ice targets with monokinetic deuterons accelerated by the U.B.C. Van de Graaff accelerator. Pulse height analysis, after amplification of the pulses, gave the energy distribution of the induced reactions, the primary reaction proceeding being Ne²⁰(n,∝)O¹⁷, with two alpha groups resulting from transitions to both the ground and first excited state of the O¹⁷ nucleus. The excitation function showed the existence of resonances in the Ne²¹ compound nucleus at the following energies, in Mev 10.04, 10.20, 10.32, 10.46, 10.63, 10.90, 11.06, 11.33, 11.44, 11.63, 11.76, 11.88, 11.96, 12.05 and 12.24. The total (n,∝) cross section varies from 90 mb to 500 mb in this energy range. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

In the first section of this thesis the measurement of the angular correlation of annihilation radiation in various materials is described. It is found that the angular dependence of the coincidence counting rate leads to results which are not in agreement with the present theories of the mechanism of positron decay processes in crystal and metal lattices. In particular, positrons do.not appear always to reach thermal energies before annihilation with electrons takes place. A search for the photodisintegration of Ne²⁰ using the gamma rays from the Li⁷(p,ɤ )Be⁸ reaction is described. An unusually low cross-section for the photo-alpha process to the ground state of O¹⁶ is found, 8 x 10⁻³⁰cm² for the 17.6 Mev. gamma ray and 3 x 10²⁹ cm² for the 14.8 Mev. gamma ray. Cross-sections of the order of 10⁻²⁸ cm² are obtained for alpha particle transitions to the 6 and 7 Mev. Excited state of O¹⁶. These cross-sections are of the usual order of magnitude for photodisintegration reactions. Irradiation of Ne²⁰ with high energy neutrons gives rise to alpha particle transitions from the Ne²¹ compound nuclear levels so formed to several excited states of O¹⁷. The excitation energies of these states are in good agreement with those measured in other nuclear reactions. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

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Thesis (M.A.)--University of Wisconsin--Madison, 1946. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 24).

Stuttgart, Universiẗat, Diss., 2001. / Erscheinungsjahr an der Haupttitelstelle: 2001.

A normal mixture of the stable neon isotopes, Ne²⁰ 90.51%, Ne²¹ 0.28%, Ne²² 9.21%, has been bombarded with 2.68 Mev. neutrons from the reaction H²(dn)He³ . A gridded ion chamber, with 1 litre sensitive volume, filled with neon to 6¼ atmospheres pressure, was used to detect disintegrations. Pulses from the ion chamber were amplified, arid recorded on an 18-channel kicksorter. The ground-state transition of Ne²⁰(nα)O¹⁷ was observed, with 1% counting statistics. The Q,-value was measured as -0.77±0.08 Mev., in fair agreement with previously reported results. Careful search failed to reveal any evidence of excited states in O¹⁷. A level at 0.87 Mev. is known, and one at 1.6 Mev. is suspected, but calculation of barrier penetrability for alpha particles corresponding to these levels indicates that they are not likely to be observed at the neutron energy used. A second reaction, with disintegration energy corresponding to a Q-value of +0.48±0.10 Mev. was also observed. It was not clear whether this reaction was N¹⁴(np)C¹⁴ or Ne²¹(nα)O¹⁸. This point is to be clarified by further investigation. / Science, Faculty of / Physics and Astronomy, Department of / Graduate