Heidelberg 2015 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 22: Instrumentation 8

HK 22.8: Talk

Tuesday, March 24, 2015, 16:15–16:30, M/HS2

Alpha Spectroscopy — Kai Zuber, •Heinrich Wilsenach, and Felix Krueger — IKTP TU-Dresden, Dresden, Germany

Alpha decays from long living isotopes are one of the limiting back- grounds for experiments searching for rare decays with stringent back- ground constrains, such as neutrinoless double beta decay experiments. It is thus very important to accurately measure the half-lifes of these decays, in order to properly model their background contribution. Therefore, it is important to be able to measure half-lifes from alpha decays of the order of 1×10¹⁵ yr. A measurement of such a long lived decay imposes, however, a series of challenges, where the correct discrimination between background and true signal is critical. There is also a more general interest in such long living half-life measurements, as their value depends crucially on the underlying nuclear model.

This talk presents a new ionisation chamber for alpha-spectroscopy that has been built from radio pure materials for the purpose to investigate long lived alpha decays. The analysis makes use of pulse shape analysis to discriminate between signal and background. The design and performance of the chamber will be presented here. A background rate of 10 counts per day in the energy region of 1-8 MeV has been achieved. A detailed investigation of Sm-isotopes was performed using high precision alpha- and gamma spectroscopy. The results of which will also be presented here as well as some results obtained with calibration sources or varying thickness.