DAMA/NaI

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 crystals [NaI(Tl)]. 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 radiation from radon daughters and other environmental effects, the copper box is enclosed inside a multi-component, multi-ton passive shield made of copper, lead, polyethylene/paraffin, and cadmium foil. A plexiglass box encloses the whole shield and is also kept in a highly pure nitrogen atmosphere. A concrete neutron moderator 1 m thick largely surrounds the set-up. The experiment followed the proposal of Pierluigi Belli (then a Ph.D. student, now a research director of the Italian National Institute of Nuclear Physics), which his research group then followed up on.

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. The final paper with the full results was published in 2003 after the end of experiment in July 2002. Various corollary investigations are continuing and have also been published.

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, for example: neutralinos, inelastic dark matter, self-interacting dark matter, and heavy 4th generation neutrinos.

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. 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 approaches.

Skepticism

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

The COSINE-100 collaboration has been working in Korea towards confirming or refuting the DAMA-signal. They are using a similar experimental setup to DAMA (NaI(Tl)-crystals). They published their results in December 2018 in the journal Nature; their conclusion was that their "result rules out WIMP–nucleon interactions as the cause of the annual modulation observed by the DAMA collaboration".

A possible explanation of the reported modulation was pointed out as originating from the data analysis procedure. A yearly subtraction of the constant component can give rise to a sawtooth residual in the presence of a slower time dependence.{{cite journal |display-authors=etal

In May 2021, the ANAIS dark matter direct detection experiment, after acquiring data for 3 years at the Canfranc Underground Laboratory in Spain, has not seen evidence for annual modulation in 112.5 kg of NaI(Tl) crystals and is thus incompatible with DAMA/NaI and DAMA/LIBRA |display-authors=etal |article-number=102005 and in November new results from COSINE-100 experiment after 1.7 years of data collection also failed to replicate the signal of DAMA.

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

References

1. (2009). "Compatibility of DAMA/LIBRA dark matter detection with other searches". [[Journal of Cosmology and Astroparticle Physics]].
2. (1998). "Searching for WIMPs by the annual modulation signature". [[Physics Letters B]].
3. (2001). "Investigating the DAMA annual modulation data in a mixed coupling framework". [[Physics Letters B]].
4. (2002). "Investigating the DAMA annual modulation data in the framework of inelastic dark matter". [[European Physical Journal C]].
5. (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]].
6. (2004). "Dark matter particles in the galactic halo: Results and implications from DAMA/NaI". [[International Journal of Modern Physics D]].
7. (2006). "Investigating pseudoscalar and scalar dark matter". [[International Journal of Modern Physics A]].
8. (2006). "Investigating halo substructures with annual modulation signature". [[European Physical Journal C]].
9. (2007). "On electromagnetic contributions in WIMP quests". [[International Journal of Modern Physics A]].
10. (2008). "Investigating electron interacting dark matter". [[Physical Review D]].
11. (2008). "Possible implications of the channeling effect in NaI(Tl) crystals". [[European Physical Journal C]].
12. (2008). "Investigation on light dark matter". [[Modern Physics Letters A]].
13. Foot, R.. (2004). "Reconciling the positive DAMA annual modulation signal with the negative results of the CDMS II experiment". [[Modern Physics Letters A]].
14. (2003). "Light Relic Neutralinos". [[Physical Review D]].
15. (2003). "Lower bound on the neutralino mass from new data on CMB and implications for relic neutralinos". [[Physical Review D]].
16. (2004). "Light neutralinos and WIMP direct searches". [[Physical Review D]].
17. (2005). "The Status of Inelastic Dark Matter". [[Physical Review D]].
18. Mitra, S.. (2005). "Has Dama Detected Self-Interacting Dark Matter?". [[Physical Review D]].
19. (2002). "Implications of a solar-system population of massive 4th generation neutrinos for underground searches of monochromatic neutrino-annihilation signals". [[Physics Letters B]].
20. (2008). "May Heavy neutrinos solve underground and cosmic ray puzzles?". [[Physics of Atomic Nuclei]].
21. (2000). "On the investigation of possible systematics in WIMP annual modulation search". [[European Physical Journal C]].
22. Matson, John. (6 May 2011). "WIMP Wars: Astronomers and physicists remain skeptical of long-standing dark matter claim".
23. (2018). "An experiment to search for dark-matter interactions using sodium iodide detectors". Nature.
24. (2023). "An induced annual modulation signature in COSINE-100 data by DAMA/LIBRA's analysis method". Scientific Reports.
25. Castelvecchi, Davide. (2022-08-16). "Notorious dark-matter signal could be due to analysis error". Nature.
26. "ANAIS Experiment | Universidad de Zaragoza".
27. (2021-11-12). "Strong constraints from COSINE-100 on the DAMA dark matter results using the same sodium iodide target". Science Advances.
28. "Is the end in sight for famous dark matter claim?".