Bonn 2010 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 36: Postersitzung

HK 36.27: Poster

Mittwoch, 17. März 2010, 14:00–16:00, HG Aula

Temperature dependence of the pulse properties and the leakage current of germanium detectors — Allen Caldwell, Daniel Lenz, Jing Liu, Xiang Liu, Bela Majorovitz, and •Oleksandr Volynets — Max-Planck-Institute for Physics, Munich, Germany

High-purity germanium detectors are used in neutrinoless double-beta decay experiments like Gerda as they have very good resolution and act as the detector and the source simultaneously.

Germanium detectors are operated at liquid nitrogen temperatures to reduce the number of electrons in the conduction band. The mobility of the charge carriers is temperature dependent and thus also the rise time of the pulses induced by the drifting charge carriers. Therefore pulse shapes analysis has to take into account possible temperature variations.

Measurements of the temperature dependence of the pulses were made using a high-purity n-type segmented germanium detector. The detector was installed in a vacuum cryostat and cooled through a copper cooling finger submerged in liquid nitrogen. A collimated ¹⁵²Eu source located at two different positions along the crystal axes 100 and 110 was used. The temperature was monitored using a PT100 resistor installed at the closest possible point to the detector. The pulse properties in the temperature range from 93 to 99 K and the temperature dependence of the leakage current in the temperature range from 85 to 112 K will be discussed.