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HK: Fachverband Physik der Hadronen und Kerne

HK 6: Instrumentation I

HK 6.2: Vortrag

Montag, 27. März 2017, 17:00–17:15, F 072

Numerical correction methods of neutron damage in position-sensitive HPGe detectors — •R. Hetzenegger, B. Birkenbach, B. Bruyneel, P. Reiter, J. Eberth, H. Hess, R. Hirsch, L. Lewandowski, and A. Vogt — IKP, Universität zu Köln

The Advanced GAmma Tracking Array (AGATA) is a major γ-ray spectrometer mainly for nuclear structure studies. AGATA is based on the novel technique of γ-ray tracking in electrically segmented high-purity Ge crystals. The array is currently employed at the Grand Accélérateur National d’Ions Lourds (GANIL, France) in stable-beam experiments with high count rates. Fast neutrons are emitted after almost any nuclear reaction with projectile energies above the Coulomb barrier. These neutrons generate crystal defects by dislocating Ge atoms. Dislocations act as hole traps within the HPGe material, causing a reduced charge collection efficiency, observed as a left tailing in the energy-peak shapes. The crystals can recover from neutron damage by annealing. However, for practical reasons, this treatment cannot be applied after every experiment. Recently, two software-based methods were developed employing pulse-shape analysis (PSA) to minimize the trapping effects between consecutive scheduled annealings of the HPGe crystals. Both approaches employ the position sensitivity of the HPGe detectors and determine the neutron trapping contribution for charge collection after individual γ-ray interactions. Energy resolution and line shape of neutron-damaged detectors are improved dramatically. Results and perspectives on neutron-damage corrections are presented. Supported by German BMBF 05P12PKFNE TP4 and 05P15PKFN9.