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HK: Fachverband Physik der Hadronen und Kerne

HK 28: Struktur und Dynamik von Kernen

HK 28.7: Vortrag

Mittwoch, 21. März 2012, 15:45–16:00, P 4

Experimental determination of the time behavior of the unobserved level feeding — •Thomas Braunroth, Alfred Dewald, Enrico Ellinger, Christoph Fransen, Matthias Hackstein, Jan Jolie, and Julia Litzinger — Institut für Kernphysik, Universität zu Köln

The Recoil Distance Doppler Shift (RDDS) technique is a powerful tool to determine lifetimes of excited nuclear states in the picosecond region. Especially when populating the state of interest by means of fusion evaporation reactions detailed level feeding has to be considered in order to obtain precise and correct level lifetimes with this technique. This includes also the time behavior of the unobserved level feeding which remains normally undetermined. The problem is solved completely by using gamma-gamma coincidence data by which the level lifetimes of interest are determined by selecting suitable feeding branches. Knowing the correct level lifetime and also the discrete level feeding, the time behavior of the unobserved feeding becomes experimentally accessible. In this paper we report on the method used and present results on the time behavior of the unobserved feeding of several yrast and non-yrast states in ¹²⁴Xe and ¹⁵⁶Dy which were populated using the reactions ¹²⁴Sn(³⁶S,4n)¹⁵⁶Dy and ¹¹⁰Pd(¹⁸O,4n)¹²⁴Xe, respectively. The results are suited to shed some light on the feeding pattern of the states considered. In the future the results can also be used to test statistical model calculations employed to describe fusion evaporation reactions.