This work focuses on new electromagnetic decay mode in nuclear physics. The first part of the thesis presents the observation of the two-photon decay for a transition where the one-photon decay is allowed. In the second part, so called quadrupole mixed-symmetry is investigated in inelastic proton scattering experiments. In 1930 Nobel-prize winner M. Goeppert-Mayer was the first to discuss the two-photon decay of an exited state in her doctoral thesis. This process has been observed many times in atomic physics. However in nuclear physics data is sparse. Here this decay mode has only been observed for the special case of a transition between nuclear states with spin and parity quantum number 0+. For such a transition, the one-photon decay - the main experimental obstacle to observe the two-photon decay - is forbidden. Furthermore, the energy sharing and angular distributions were measured, allowing conclusions to be drawn about the multipoles contributing to the two-photon transition. Quadrupole mixed-symmetry states are an excitation mode in spherical nuclei which are sensitive to the strength of the quadrupole residual interaction. A new signature for these interesting states is presented which allows identification of mixed-symmetry states independently of electromagnetic transition strengths. Furthermore this signature represents a valuable additional observable to test model predictions for mixed-symmetry states.

This work focuses on new electromagnetic decay mode in nuclear physics. The first part of the thesis presents the observation of the two-photon decay for a transition where the one-photon decay is allowed. In the second part, so called quadrupole mixed-symmetry is investigated in inelastic proton scattering experiments. In 1930 Nobel-prize winner M. Goeppert-Mayer was the first to discuss the two-photon decay of an exited state in her doctoral thesis. This process has been observed many times in atomic physics. However in nuclear physics data is sparse. Here this decay mode has only been observed for the special case of a transition between nuclear states with spin and parity quantum number 0+. For such a transition, the one-photon decay - the main experimental obstacle to observe the two-photon decay - is forbidden. Furthermore, the energy sharing and angular distributions were measured, allowing conclusions to be drawn about the multipoles contributing to the two-photon transition. Quadrupole mixed-symmetry states are an excitation mode in spherical nuclei which are sensitive to the strength of the quadrupole residual interaction. A new signature for these interesting states is presented which allows identification of mixed-symmetry states independently of electromagnetic transition strengths. Furthermore this signature represents a valuable additional observable to test model predictions for mixed-symmetry states.

Studienarbeit aus dem Jahr 2004 im Fachbereich Geschichte - Weltgeschichte - Fruhgeschichte, Antike, Note: 1, Universitat Leipzig (Historisches Seminar), 25 Quellen im Literaturverzeichnis, Sprache: Deutsch, Abstract: Im 3. Jahrhundert kam es zu mehreren Seuchenwellen in Alexandria, Carthago und anderen Orten. Diese Seuchen wurden von der Forschung lange als eines von diversen Phanomenen einer Globalkrise der Romischen Reichs angesehen. Eng verbunden damit ist die Diskussion um Ursachen fur den Untergang des Reichs. Neben den Seuchen kam es zu wirtschaftlichen Krisen, zu gewaltsamen und schnellen Thronwechseln, zu zahlreichen Barbaren"-Einfallen, unsicheren Grenzen und anderen Krisen"-Phanomenen. Die Interpretation einer umfassenden Krise wird von der neueren Forschung jedoch zunehmend hinterfragt (Vgl. v.a. Witschel 1999). In dieser Arbeit wird der Frage nachgegangen, was den vorhandenen Quellen tatsachlich an brauchbaren Informationen entnommen werden kann. Es soll abgewogen werden, welche Schlussfolgerungen daraus fur das Ausmass und die demographischen Auswirkungen der Seuchen moglich sind. Des weiteren stellt sich die Frage, ob die Seuchen subjektiv als Krisenphanomen wahrgenommen wurden. Das Fehlen statistischer Daten zwingt dazu, sich vor allem an literarischen Quellen zu orientieren, also an Briefen, Chroniken usw., in denen allein direkte Aussagen zu Seuchen zu finden sind. Die uberlieferten zeitgenossischen Quellen (Dionysius, Cyprian) sowie spatere, historiographische Zeugnisse der Antike (Zosimus, Orosius, Historia Augusta, Eutropius, Zonaras) werden kritisch untersucht. Des weiteren werden die verschiedenen Versuche der Forschung, aus anderen Quellen indirekte Hinweise zu Seuchen und demographischen Entwicklungen des 3. Jahrhunderts herauszulesen, vorgestellt und eingeschatzt. Wierschowski (1994), Duncan-Jones (1996), Haberman (1998). Die grundsatzliche Moglichkeit, demographische Aussagen fur die Antike zu machen, wurde u.a. von Boak (1955), Finley (