Münster 2011 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 54: Instrumentierung IX

HK 54.4: Vortrag

Donnerstag, 24. März 2011, 14:45–15:00, HS1

Continuous Angle DSAM: A new quality of lifetime measurements — •Christian Stahl, Jörg Lesk, and Norbert Pietralla — Institut für Kernpysik, Technische Universität Darmstadt

The Doppler-Shift-Attenuation-Method (DSAM) for lifetime determination below approx. 10 ps is based on the analysis of Doppler-broadened lineshapes from gamma rays emitted during the deceleration process of ions in matter. The sensitivity of this method can be limited inter alia by contaminant lines overlapping the lineshape of interest as well as by the finite solid angle covered by the gamma detector that causes a smearing-out of the lineshape due to the ignorance of the gamma ray interaction point in the detector.

With the development of highly segmented HPGe detectors like the Advanced Gamma-ray Tracking Array (AGATA) a superior position resolution of gamma-ray interaction points over a wide range of angles will be achieved, providing the possibility to generate gamma spectra that are continuous in the angle between the momentum vectors of the de-exciting ion and the gamma quantum. Extracting the lifetime of an excited nuclear state from these 2D spectra represents a new quality of DSAM lifetime measurements, in particular, for low-intensity spectra as expected from spectroscopy with radioactive ion beams. For this purpose a new realistic Monte-Carlo simulation of the stopping process of ions from Coulex reactions as well as a program for lineshape analysis based on the convolution technique were developed.