DAMA/NaI

The DAMA/NaI experiment[1][2] investigated the presence of dark matter particles in the galactic halo by exploiting the model-independent annual modulation signature. Based on the Earth's orbit around the Sun and the solar system's speed with respect to the center of the galaxy (which on short time scales call be considered constant), the Earth should be exposed to a higher flux of dark matter particles around June 2, when its orbital speed is added to the one of the solar system with respect to the galaxy and to a smaller one around December 2, when the two velocities are subtracted. The annual modulation signature is distinctive since the effect induced by dark matter particles must simultaneously satisfy many requirements.

Description

The experimental set-up was located deep underground in the Laboratori Nazionali del Gran Sasso in Italy.

The experimental set-up was made by nine 9.70 kg low-radioactivity scintillating thallium-doped sodium iodide (NaI(Tl)) crystals. Each crystal was faced by two low-background photomultipliers through 10 cm light guides. The detectors were installed inside a sealed copper box flushed with highly pure nitrogen in order to insulate the detectors from air that contains trace amounts of radon, a radioactive gas. To reduce the natural environmental background the copper box is enclosed inside a multicomponent multi-ton passive shield made of copper, lead, polyethylene/paraffin, cadmium foil. A plexiglas box encloses the whole shield and is also kept in a highly pure nitrogen atmosphere. A 1 m concrete neutron moderator largely surrounds the set-up.

Results

The DAMA/NaI set-up observed the annual modulation signature over 7 annual cycles (1995-2002). The presence of a model independent positive evidence in the data of DAMA/NaI was first reported by the DAMA collaboration in fall 1997 and published beginning of 1998.[3] The final paper with the full results was published in 2003[1] after the end of experiment in July 2002. Various corollary investigations have also been and are continuing.[4][5][6][7][8][9][10][11][12][13]

The model-independent evidence is compatible with a wide set of scenarios regarding the nature of the dark matter candidate and related astrophysical, nuclear and particle physics [14] (for example : neutralinos,[15][16][17] inelastic dark matter,[18] Self-interacting dark matter,[19] and heavy 4th generation neutrinos[20][21]).

A careful quantitative investigation of possible sources of systematic and side reactions has been regularly carried out and published at the time of each data release.[22] No systematic effect or side reaction able to account for the observed modulation amplitude and to simultaneously satisfy all the requirements of the signature has been found.

The experiment has also obtained and published many results on other processes and/or approaches.

Skepticism

Negative results from the XENON Dark Matter Search Experiment seem to contradict DAMA/Nal's results.[23]

Follow up

DAMA/NaI has been replaced by the new generation experiment, DAMA/LIBRA. These experiments are carried out by Italian and Chinese researchers.

References

  1. 1 2 R. Bernabei; et al. (2003). "Dark Matter search". Rivista del Nuovo Cimento. 26 (1): 1. Bibcode:2003NCimR..26a...1B. arXiv:astro-ph/0307403 Freely accessible.
  2. ↑ R. Bernabei; et al. (1999). "Performances of the about 100 kg NaI(Tl) set-up of the DAMA experiment at Gran Sasso". Il Nuovo Cimento A. 112 (6): 545. Bibcode:1999NCimA.112..545B. doi:10.1007/BF03035868.
  3. ↑ R. Bernabei; et al. (1998). "Searching for WIMPs by the annual modulation signature". Physics Letters B. 424: 195. Bibcode:1998PhLB..424..195B. doi:10.1016/S0370-2693(98)00172-5.
  4. ↑ R. Bernabei; et al. (2001). "Investigating the DAMA annual modulation data in a mixed coupling framework". Physics Letters B. 509 (3–4): 197. Bibcode:2001PhLB..509..197B. doi:10.1016/S0370-2693(01)00493-2.
  5. ↑ R. Bernabei; et al. (2002). "Investigating the DAMA annual modulation data in the framework of inelastic dark matter". European Physical Journal C. 23: 61. Bibcode:2002EPJC...23...61B. doi:10.1007/s100520100854.
  6. ↑ P. Belli; et al. (2002). "Effect of the galactic halo modeling on the DAMA-NaI annual modulation result: An extended analysis of the data for weakly interacting massive particles with a purely spin-independent coupling". Physical Review D. 66 (4): 043503. Bibcode:2002PhRvD..66d3503B. arXiv:hep-ph/0203242 Freely accessible. doi:10.1103/PhysRevD.66.043503.
  7. ↑ R. Bernabei; et al. (2004). "Dark Matter particles in the galactic halo: results and implications from DAMA/NaI". International Journal of Modern Physics D. 13 (10): 2127. Bibcode:2004IJMPD..13.2127B. arXiv:astro-ph/0501412 Freely accessible. doi:10.1142/S0218271804006619.
  8. ↑ R. Bernabei; et al. (2006). "Investigating pseudoscalar and scalar dark matter". International Journal of Modern Physics A. 21 (7): 1445. Bibcode:2006IJMPA..21.1445B. arXiv:astro-ph/0511262 Freely accessible. doi:10.1142/S0217751X06030874.
  9. ↑ R. Bernabei; et al. (2004). "Investigating halo substructures with annual modulation signature". European Physical Journal C. 47: 263. Bibcode:2006EPJC...47..263B. arXiv:astro-ph/0604303 Freely accessible. doi:10.1140/epjc/s2006-02559-9.
  10. ↑ R. Bernabei; et al. (2007). "On electromagnetic contributions in WIMP quests". International Journal of Modern Physics A. 22 (19): 3155. Bibcode:2007IJMPA..22.3155B. arXiv:0706.1421 Freely accessible. doi:10.1142/S0217751X07037093.
  11. ↑ R. Bernabei; et al. (2008). "Investigating electron interacting dark matter". Physical Review D. 77 (2): 023506. Bibcode:2008PhRvD..77b3506B. arXiv:0706.1421 Freely accessible. doi:10.1103/PhysRevD.77.023506.
  12. ↑ R. Bernabei; et al. (2008). "Possible implications of the channeling effect in NaI(Tl) crystals". European Physical Journal C. 53 (2): 205. Bibcode:2008EPJC...53..205B. arXiv:0710.0288 Freely accessible. doi:10.1140/epjc/s10052-007-0479-0.
  13. ↑ R. Bernabei; et al. (2008). "Investigation on light dark matter". Modern Physics Letters A. 23 (26): 2125. Bibcode:2008MPLA...23.2125B. arXiv:0802.4336 Freely accessible. doi:10.1142/S0217732308027473.
  14. ↑ R. Foot (2004). "Reconciling the positive DAMA annual modulation signal with the negative results of the CDMS II experiment". Modern Physics Letters A. 19 (24): 1841. Bibcode:2004MPLA...19.1841F. arXiv:astro-ph/0405362 Freely accessible. doi:10.1142/S0217732304015051.
  15. ↑ A. Bottino; et al. (2003). "Light Relic Neutralinos". Physical Review D. 67 (6): 063519. Bibcode:2003PhRvD..67f3519B. arXiv:hep-ph/0212379 Freely accessible. doi:10.1103/PhysRevD.67.063519.
  16. ↑ A. Bottino; et al. (2003). "Lower Bound on the Neutralino Mass from New Data on CMB and Implications for Relic Neutralinos". Physical Review D. 68 (4): 043506. Bibcode:2003PhRvD..68d3506B. arXiv:hep-ph/0304080 Freely accessible. doi:10.1103/PhysRevD.68.043506.
  17. ↑ A. Bottino; et al. (2004). "Light Neutralinos and WIMP direct searches". Physical Review D. 69 (3): 037302. Bibcode:2004PhRvD..69c7302B. arXiv:hep-ph/0307303 Freely accessible. doi:10.1103/PhysRevD.69.037302.
  18. ↑ D.T. Smith; N. Weiner (2005). "The Status of Inelastic Dark Matter". Physical Review D. 72 (6): 063509. Bibcode:2005PhRvD..72f3509T. arXiv:hep-ph/0402065 Freely accessible. doi:10.1103/PhysRevD.72.063509.
  19. ↑ S. Mitra (2005). "Has Dama Detected Self-Interacting Dark Matter?". Physical Review D. 71 (12): 121302. Bibcode:2005PhRvD..71l1302M. arXiv:astro-ph/0409121 Freely accessible. doi:10.1103/PhysRevD.71.121302.
  20. ↑ K.M. Belotsky; T. Damour; M. Yu. Khlopov (2002). "Implications of a solar-system population of massive 4th generation neutrinos for underground searches of monochromatic neutrino-annihilation signals". Physics Letters B. 529: 10. Bibcode:2002PhLB..529...10B. arXiv:astro-ph/0201314 Freely accessible. doi:10.1016/S0370-2693(02)01234-0.
  21. ↑ K. Belotsky; D. Fargion; M. Khlopov; R.V. Konoplich (2008). "May Heavy neutrinos solve underground and cosmic ray puzzles?". Physics of Atomic Nuclei. 71: 147. Bibcode:2008PAN....71..147B. arXiv:hep-ph/0411093 Freely accessible. doi:10.1007/s11450-008-1016-9.
  22. ↑ R. Bernabei; et al. (2000). "On the investigation of possible systematics in WIMP annual modulation search". European Physical Journal C. 18 (2): 283. Bibcode:2000EPJC...18..283B. doi:10.1007/s100520000540.
  23. ↑ Matson, John (6 May 2011). "WIMP Wars: Astronomers and Physicists Remain Skeptical of Long-Standing Dark Matter Claim". Scientific American. Retrieved 12 April 2011.
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