COBRA Experiment

Cadmium Zinc Telluride 0-Neutrino Double-Beta Research Apparatus
Research type Particle physics, Astrophysics
Location L'Aquila, Abruzzo, Italy
42°27′14″N 13°34′34″E / 42.454°N 13.576°E / 42.454; 13.576Coordinates: 42°27′14″N 13°34′34″E / 42.454°N 13.576°E / 42.454; 13.576
Operating agency
 INFN
Website www.cobra-experiment.org

The Cadmium Zinc Telluride 0-Neutrino Double-Beta(COBRA) experiment is a large array of Cadmium Zinc Telluride(CZT) semiconductors currently being utilized to search for evidence of the neutrino-less double beta decay, and to measure it's half life, this should act as a probe to physics beyond The Standard Model as well as finding the neutrino mass. It is located within the Gran Sasso National Laboratory (LNGS). Papers on this method have been published since 2001 and installation of a large prototype began in 2006.[1]

Set up

The COBRA experiment is currently in the research & development stages, in order to prove the validity of the proposed techniques.[2] The initial set up of the experiment was an array of four CZT semiconductors in 2007.[3] Currently, the experiment is composed of 64 detectors in a 4x4x4 array, 32 of which are currently active.[4] The CdZnTe crystals act as both detector and source material, as nine of the isotopes in this material are possible double beta decay candidates.[5] The location of the experiment allows for shielding from external gamma rays, to this end, the detectors are also shielded by 5 cm of radiopure electrolytic copper and 20 cm low-radioactivity lead. 7 cm of boron-loaded polyethylene shields the experiment against neturons, and the experiment is constantly flushed with nitrogen gas to prevent contamination with radon.[6]

Results

COBRA has collected about 200 kg days of calibrated exposure, these data are being analysed in order to understand the background factors and to determine half life limits for isotopes of interest.[7] Current efforts are focused on reducing the background readings in order to increase the sensitivity of the experiment.[8] Another potential solution is to use liquid scintillators as a low-noise background for the detectors, which has been proven possible in other experiments.[9][10]

References

  1. ↑ , [p. 2, The Cobra Experiment, J.R. Wilson, University of Sussex, 2008]
  2. ↑ [Gran Sasso COBRA section]
  3. ↑ [First results on double β-decay modes of Cd, Te, and Zn Isotopes, T.Bloxham et al. , Phys. Rev. C 76, 025501, 2007]
  4. ↑ [Gran Sasso Website]
  5. ↑ [Table 1, Current Status and Future Perspectives of the COBRA Experiment, J. Ebert et. al, 2013]
  6. ↑ [Section 2, Current Status and Future Perspectives of the COBRA Experiment, J. Ebert et. al, 2013]
  7. ↑
  8. ↑ [Neutrinoless double beta decay, the inverted hierarchy, and precision determination of θ12, Alexander Dueck et. al, 2011]
  9. ↑ [Measurements of extremely low radioactivity levels in BOREXINO, C. Arpesella et. al, 2002]
  10. ↑ [First Results from KamLAND: Evidence for Reactor Antineutrino Disappearance, K. Eguchi et al., 2003]

External links

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