Published October 2013 | Version v1
Journal article Metadata-only

Pulse shape discrimination for Gerda Phase I data

Creators

  • 1. Technische Universitaet Muenchen, Physik Department and Excellence Cluster Universe, Muenchen (Germany)
  • 2. Technische Universitaet Dresden, Institut fuer Kern- und Teilchenphysik, Dresden (Germany)
  • 3. Eberhard Karls Universitaet Tuebingen, Physikalisches Institut, Tuebingen (Germany)
  • 4. Institute for Reference Materials and Measurements, Geel (Belgium)
  • 5. National Research Centre ''Kurchatov Institute'', Moscow (Russian Federation)
  • 6. LNGS, INFN Laboratori Nazionali del Gran Sasso, Assergi (Italy)
  • 7. Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation)
  • 8. Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany)
  • 9. Physik Institut der Universitaet Zuerich, Zuerich (Switzerland)
  • 10. Max-Planck-Institut fuer Physik, Muenchen (Germany)
  • 11. INFN Milano Bicocca, Milano (Italy)
  • 12. Universita Milano Bicocca, Dipartimento di Fisica, Milano (Italy)
  • 13. Institute for Theoretical and Experimental Physics, Moscow (Russian Federation)
  • 14. INFN Padova, Padova (Italy)
  • 15. Universita di Padova, Dipartimento di Fisica e Astronomia, Padova (Italy)
  • 16. Joint Institute for Nuclear Research, Dubna (Russian Federation)
  • 17. Jagiellonian University, Institute of Physics, Cracow (Poland)
  • 18. INFN Milano, Dipartimento di Fisica, Milano (IT)
  • 19. Universita degli Studi di Milano (IT)
  • 20. National Research Centre ''Kurchatov Institute'', Moscow (RU)
  • 21. Joint Institute for Nuclear Research, Dubna (RU)
  • 22. Eberhard Karls Universitaet Tuebingen, Physikalisches Institut, Tuebingen (DE)
  • 23. INFN Padova, Padova (IT)
  • 24. Universita di Padova, Dipartimento di Fisica e Astronomia, Padova (IT)

Description

The Gerda experiment located at the Laboratori Nazionali del Gran Sasso of INFN searches for neutrinoless double beta (0νββ) decay of 76Ge using germanium diodes as source and detector. In Phase I of the experiment eight semi-coaxial and five BEGe type detectors have been deployed. The latter type is used in this field of research for the first time. All detectors are made from material with enriched 76Ge fraction. The experimental sensitivity can be improved by analyzing the pulse shape of the detector signals with the aim to reject background events. This paper documents the algorithms developed before the data of Phase I were unblinded. The double escape peak (DEP) and Compton edge events of 2.615 MeV γ rays from 208Tl decays as well as two-neutrino double beta (2νββ) decays of 76Ge are used as proxies for 0νββ decay. For BEGe detectors the chosen selection is based on a single pulse shape parameter. It accepts 0.92±0.02 of signal-like events while about 80 % of the background events at Qββ =2039 keV are rejected. For semi-coaxial detectors three analyses are developed. The one based on an artificial neural network is used for the search of 0 νββ decay. It retains 90 % of DEP events and rejects about half of the events around Qββ. The 2 νββ events have an efficiency of 0.85 ±0.02 and the one for 0 νββ decays is estimated to be 0.90+0.05-0.09. A second analysis uses a likelihood approach trained on Compton edge events. The third approach uses two pulse shape parameters. The latter two methods confirm the classification of the neural network since about 90 % of the data events rejected by the neural network are also removed by both of them. In general, the selection efficiency extracted from DEP events agrees well with those determined from Compton edge events or from 2νββ decays. (orig.)

Availability note (English)

Available from: http://dx.doi.org/10.1140/epjc/s10052-013-2583-7

Additional details

Identifiers

DOI
10.1140/epjc/s10052-013-2583-7;

Publishing Information

Journal Title
European Physical Journal. C
Journal Volume
73
Journal Issue
10
Journal Page Range
p. 1-17
ISSN
1434-6044

INIS

Country of Publication
Germany
Country of Input or Organization
Germany
INIS RN
45021874
Subject category
S46: INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY;
Descriptors DEI
ALGORITHMS; BACKGROUND RADIATION; BETA DETECTION; CALIBRATION; DATA PROCESSING; DELAYED GAMMA RADIATION; DOUBLE BETA DECAY; ENERGY DEPENDENCE; GAMMA DETECTION; GE SEMICONDUCTOR DETECTORS; LOW LEVEL COUNTING; MAXIMUM-LIKELIHOOD FIT; MEV RANGE 01-10; PARTICLE DISCRIMINATION; PULSE TECHNIQUES
Descriptors DEC
BETA DECAY; BETA-MINUS DECAY; CHARGED PARTICLE DETECTION; COUNTING TECHNIQUES; DECAY; DETECTION; ELECTROMAGNETIC RADIATION; ENERGY RANGE; GAMMA RADIATION; IONIZING RADIATIONS; MATHEMATICAL LOGIC; MATHEMATICAL SOLUTIONS; MEASURING INSTRUMENTS; MEV RANGE; NUCLEAR DECAY; NUMERICAL SOLUTION; PARTICLE IDENTIFICATION; PROCESSING; RADIATION DETECTION; RADIATION DETECTORS; RADIATIONS; SEMICONDUCTOR DETECTORS