EDELWEISS

Source: Wikipedia, the free encyclopedia.
For other uses, see Edelweiss (disambiguation).
The EDELWEISS logo

EDELWEISS (Expérience pour DEtecter Les WIMPs En Site Souterrain) is a

cryogenic detectors, measuring both the phonon and ionization signals produced by particle interactions in germanium
crystals. This technique allows nuclear recoils events to be distinguished from electron recoil events.

The EURECA project is a proposed future dark matter experiment, which will involve researchers from EDELWEISS and the CRESST dark matter search.

Dark matter

Main article: dark matter

Dark matter is material which does not emit or absorb light. Measurements of the

cosmic microwave background radiation
suggest it accounts for a significant fraction of the density of the Universe.

A possible explanation of dark matter comes from

cosmic rays
).

Experiment

EDELWEISS is located in the Modane underground laboratory, in the Fréjus road tunnel between France and Italy, below 1800m of rock. A 20 cm lead shield reduces the gamma background, and a polyethylene shield reduces the neutron flux. All materials close to the detectors are screened for radiopurity. A dilution refrigerator is used to cool the detectors, built in the opposite orientation to most instruments with the detectors at the top and the refrigeration mechanism below.

EDELWEISS uses high purity

Lawrence M. Krauss, Mark Srednicki and Frank Wilczek.[1]

A major limitation of early detectors was the problem of surface events. Due to incomplete charge collection, a particle interaction near the surface of the crystal gave no ionization signal, so electron recoils near the surface could be mistaken for nuclear recoils. To avoid this, the collaboration developed new detectors with interdigitised electrodes. Different voltages are applied to a series of electrodes so the direction of electric field is different near the surface of the crystal, allowing over 99.5% of surface events to be rejected.[2]

Results

Fig A. EDELWEISS I results. With CDMS parameter space excluded as of 2004. DAMA result is located in green area and is disallowed.

The results from the first phase of the experiment (EDELWEISS I) were published in 2005, excluding WIMP dark matter with an interaction cross-section above ≈10−6 pb (at ≈85 GeV).[3]: Fig 15 

EDELWEISS-II ran 2009–10 with 10 detectors, that is, 4 kg of detector mass (for a total effective exposure of 384 kg·d)[4] limiting high mass[4]: Fig 5  and low mass WIMPs,[5] and axions.[6] A cross-section of 4.4×10−8 pb is excluded at 90% C.L. for WIMP mass of 85 GeV. (Just above projected CDMS results in Fig A.)

EDELWEISS-III had 40 detectors.[6] EDELWEISS-III conducted first science run 2014-2015 with results published in 2016.

EURECA design work will continue for operation after the EDELWEISS-III run. It is planned that EURECA would start operating after 2017.

Collaboration

EDELWEISS is a collaboration of the following member institutions:

CEA – Commissariat à l'Énergie Atomique

CNRS – Centre National de la Recherche Scientifique

  • CSNSM - Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, Orsay
  • IPNL - Institut de Physique Nucléaire de Lyon
  • Institut NÉEL, Grenoble
  • IAS - Institut d'Astrophysique Spatiale, Paris

Institutions outside France

  • Universität Karlsruhe
    , Germany
  • Forschungszentrum Karlsruhe
    , Germany
  • JINR
    – Joint Institute for Nuclear Research, Dubna, Russia
  • University of Oxford

References

  1. ^ Krauss, L.; Srednicki, M.; Wilczek, F. (1986). "Solar System Constraints and Signatures for Dark Matter Candidates".
    PMID 9956878
    .
  2. ^ Juillard, A. (2008). "Status of the EDELWEISS-II Experiment".
    S2CID 123956512
    .
  3. ^ Sanglard, V.; et al. (EDELWEISS Collaboration) (2005). "Final results of the EDELWEISS-I dark matter search with cryogenic heat-and-ionization Ge detectors".
    S2CID 119449115
    .
  4. ^ a b Armengaud, E.; et al. (EDELWEISS Collaboration) (2011). "Final results of the EDELWEISS-II WIMP search using a 4-kg array of cryogenic germanium detectors with interleaved electrodes".
    S2CID 118504484
    .
  5. ^ Armengaud, E.; et al. (EDELWEISS Collaboration) (2012). "A search for low-mass WIMPs with EDELWEISS-II heat-and-ionization detectors".
    S2CID 119225855
    .
  6. ^ a b Armengaud, E.; et al. (EDELWEISS Collaboration) (2013). "Axion searches with the EDELWEISS-II experiment".
    S2CID 118510427
    .

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=EDELWEISS&oldid=1208994567"