Speaker
Description
One of the most important topics to get highly sensitive detection setups is the use of radiopure materials. To validate and classify these materials screening is required, where the usual methods are ICPMS and gamma spectrometry. However, alpha spectrometry can be used as an alternative method for large surface components. An advantage of alpha spectrometry is its sensitivity to multiple radioisotopes of the natural decay chains. It can thus measure if the secular equilibrium is broken and can also be combined with the other two methods to determine whether radioactive impurities are in the bulk or on the surface of a material.
At Dresden University of Technology, we have developed a low background alpha detector, a cylindrical Frisch-grid ionization chamber with a diameter of 30 cm. Using pulse shape discrimination, the detector can reach a very low background, measuring less than 20 events per day between 1 to 10 MeV. And in contrast to commercial alpha spectrometers, it offers a high resolution of 1.5 % at 5.5 MeV. However, the detector was previously only used for comparatively small samples. Therefore, the detection efficiency and event reconstruction of extended samples need to be studied.
In this poster I will present this experimental setup and the steps of data evaluation to mitigate background sufficiently. I show my current work on detector characterization, which focuses on efficiency determination for extended samples while keeping a high sensitivity. I will conclude with our most recent screening results on PEN foils, which shall be installed in the LEGEND experiment to mitigate argon-induced background.