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Tommaso Comellato

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+49 89 289-12475
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Experimental Astro-Particle Physics

Courses and Dates

Offered Bachelor’s or Master’s Theses Topics

The P+ spoiler: from minerals to alpha-decay tagging
In the last decade, experiments searching for neutrinoless double-beta decay of 76Ge provided the most stringent limits on the half-life of the process. This was possible thanks to the careful choice of clean materials and very efficient background reduction techniques. The combination of the two allowed to simplify the search for neutrinoless double-beta decay into the search for an energy peak on a null background. This work will focus on one source of background, which is the alpha-decays of radioactive contaminants on the surface of germanium detectors. Such a contamination can occur when detectors are exposed to air, thus Radon, which can deposit its radioactive progeny on their surface. The tagging of these alpha events with small anode detectors has proved to be very efficient; indeed, no events in the alpha peak have survived the analysis cuts in the full dataset of the GERDA experiment, and only a limit for the tagging efficiency has been extracted. In view of the future LEGEND experiment, the “p+ spoiler” setup was designed to build a high statistics sample of alpha decays on the surface of germanium detectors and extract the central value of their tagging efficiency. This is done by exposing detectors to an Autunite mineral, which, containing Uranium, works as a constant Radon emanator. In this thesis, the student will work on the data acquired from a germanium detector which has been “spoiled” for several months. They will be guided to the analysis of its data and to the final extraction of the tagging efficiency of alpha-decays. A background in programming in C/C++ is welcome, but not mandatory. The theses will be carried out at the Chair for astroparticle physics of the Physics Department. Supervision at the Physics Department by Prof. Schönert and Tommaso Commelato. Please contact or for further information. We will organize a dedicated meeting for interested students on Tuesday, February 1, 14:00-16:00. For more information please check
suitable as
  • Bachelor’s Thesis Physics
Supervisor: Stefan Schönert
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