Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

An experiment to search for dark-matter interactions using sodium iodide detectors

Nature volume 564, pages 83–86 (2018)Cite this article

Subjects

An Author Correction to this article was published on 21 January 2019

This article has been updated

Abstract

Observations of galaxies and primordial radiation suggest that the Universe is made mostly of non-luminous dark matter1,2. Several new types of fundamental particle have been proposed as candidates for dark matter3, such as weakly interacting massive particles (WIMPs)4,5. These particles would be expected to interact with nuclei in suitable detector materials on Earth, for example, causing them to recoil. However, no definitive signal from such dark-matter interactions has been detected despite concerted efforts by many collaborations6. One exception is the much-debated claim by the DAMA collaboration of a statistically significant (more than nine standard deviations) annual modulation in the rate of nuclear interaction events. Annual modulation is expected because of the variation in Earth’s velocity relative to the Galaxy’s dark-matter halo that arises from Earth’s orbital motion around the Sun. DAMA observed a modulation in the rate of interaction events in their detector7,8,9 with a period and phase consistent with that expected for WIMPs10,11,12. Several groups have been working to develop experiments with the aim of reproducing DAMA’s results using the same target medium (sodium iodide)13,14,15,16,17. To determine whether there is evidence for an excess of events above the expected background in sodium iodide and to look for evidence of an annual modulation, the COSINE-100 experiment uses sodium iodide as the target medium to carry out a model-independent test of DAMA’s claim. Here we report results from the initial operation of the COSINE-100 experiment related to the first task18,19. We observe no excess of signal-like events above the expected background in the first 59.5 days of data from COSINE-100. Assuming the so-called standard dark-matter halo model, this result rules out spin-independent WIMP–nucleon interactions as the cause of the annual modulation observed by the DAMA collaboration20,21,22,23. The exclusion limit on the WIMP–sodium interaction cross-section is 1.14 × 10−40 cm2 for 10-GeV c−2 WIMPs at a 90% confidence level. The COSINE-100 experiment will continue to collect data for two more years, enabling a model-independent test of the annual modulation observed by the DAMA collaboration.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Efficiency of event selection.
Fig. 2: Measured and simulated energy spectra.
Fig. 3: Fit results for a WIMP mass of 10 GeV c−2.
Fig. 4: Exclusion limits on the WIMP–nucleon spin-independent cross-section.

Similar content being viewed by others

Data availability

The data that support the findings of this study are available from the corresponding authors on reasonable request. Source Data for Figs. 1–4 are provided with the online version of the paper.

Change history

  • 21 January 2019

    In this Letter, owing to an error during the production process, ‘spin-independent’ was omitted from a sentence in the Abstract, which should read: “Assuming the so-called standard dark-matter halo model, this result rules out spin-independent WIMP–nucleon interactions as the cause of the annual modulation observed by the DAMA collaboration”. This omission has been corrected online.

References

  1. Clowe, D. et al. A direct empirical proof of the existence of dark matter. Astrophys. J. 648, L109–L113 (2006).

    Article  CAS  ADS  Google Scholar 

  2. Ade, P. A. R. et al. Planck 2015 results. XIII. Cosmological parameters. Astron. Astrophys. 594, A13 (2016).

    Article  Google Scholar 

  3. Baer, H., Choi, K.-Y., Kim, J. E. & Roszkowski, L. Dark matter production in the early Universe: beyond the thermal WIMP paradigm. Phys. Rep. 555, 1–60 (2015).

    Article  CAS  ADS  MathSciNet  Google Scholar 

  4. Lee, B. W. & Weinberg, S. Cosmological lower bound on heavy-neutrino masses. Phys. Rev. Lett. 39, 165–168 (1977).

    Article  CAS  ADS  Google Scholar 

  5. Goodman, M. W. & Witten, E. Detectability of certain dark matter candidates. Phys. Rev. D 31, 3059–3063 (1985).

    Article  CAS  ADS  Google Scholar 

  6. Battaglieri, M. et al. US cosmic visions: new ideas in dark matter 2017: community report. Preprint at https://arxiv.org/abs/1707.04591 (2017).

  7. Bernabei, R. et al. Searching for WIMPs by the annual modulation signature. Phys. Lett. B 424, 195–201 (1998).

    Article  CAS  ADS  Google Scholar 

  8. Bernabei, R. et al. Final model independent result of DAMA/LIBRA-phase1. Eur. Phys. J. C 73, 2648 (2013).

    Article  ADS  Google Scholar 

  9. Bernabei, R. et al. First model independent results from DAMA/LIBRA-phase2. Preprint at https://arxiv.org/abs/1805.10486 (2018).

  10. Savage, C., Gelmini, G., Gondolo, P. & Freese, K. Compatibility of DAMA/LIBRA dark matter detection with other searches. J. Cosmol. Astropart. Phys. 4, 10 (2009).

    Article  ADS  Google Scholar 

  11. Baum, S., Freese, K. & Kelso, C. Dark matter implications of DAMA/LIBRA-phase2 results. Preprint at https://arxiv.org/abs/1804.01231 (2018).

  12. Kang, S., Scopel, S., Tomar, G. & Yoon, J.-H. DAMA/LIBRA-phase2 in WIMP effective models. J. Cosmol. Astropart. Phys. 7, 16 (2018).

    Article  ADS  Google Scholar 

  13. Barbosa de Souza, E. et al. First search for a dark matter annual modulation signal with NaI(Tl) in the Southern Hemisphere by DM-Ice17. Phys. Rev. D 95, 032006 (2017).

    Article  ADS  Google Scholar 

  14. Amaré, J. et al. Status of the ANAIS dark matter project at the Canfranc Underground Laboratory. J. Phys. Conf. Ser. 718, 042052 (2016).

    Article  Google Scholar 

  15. Fushimi, K. et al. Dark matter search project PICO-LON. J. Phys. Conf. Ser. 718, 042022 (2016).

    Article  Google Scholar 

  16. Xu, J., Calaprice, F., Froborg, F., Shields, E. & Suerfu, B. SABRE – a test of DAMA with high-purity NaI(Tl) crystals. AIP Conf. Proc. 1672, 040001 (2015).

    Article  Google Scholar 

  17. Adhikari, P. et al. Understanding internal backgrounds in NaI(Tl) crystals toward a 200 kg array for the KIMS-NaI experiment. Eur. Phys. J. C 76, 185 (2016).

    Article  ADS  Google Scholar 

  18. Adhikari, G. et al. Initial performance of the COSINE-100 experiment. Eur. Phys. J. C 78, 107 (2018).

    Article  ADS  Google Scholar 

  19. Adhikari, P. et al. Background model for the NaI(Tl) crystals in COSINE-100. Eur. Phys. J. C 78, 490 (2018).

    Article  CAS  ADS  Google Scholar 

  20. Tanabashi, M. et al. The review of particle physics. Phys. Rev. D 98, 030001 (2018).

    Article  ADS  Google Scholar 

  21. Drukier, A. K., Freese, K. & Spergel, D. N. Detecting cold dark-matter candidates. Phys. Rev. D 33, 3495–3508 (1986).

    Article  CAS  ADS  Google Scholar 

  22. Freese, K., Frieman, J. A. & Gould, A. Signal modulation in cold dark matter detection. Phys. Rev. D 37, 3388–3405 (1988).

    Article  CAS  ADS  Google Scholar 

  23. Lewin, J. & Smith, P. Review of mathematics, numerical factors, and corrections for dark matter experiments based on elastic nuclear recoil. Astropart. Phys. 6, 87–112 (1996).

    Article  ADS  Google Scholar 

  24. Park, J. S. et al. Performance of a prototype active veto system using liquid scintillator for a dark matter search experiment. Nucl. Instrum. Methods A 851, 103–107 (2017).

    Article  CAS  ADS  Google Scholar 

  25. Prihtiadi, H. et al. Muon detector for the COSINE-100 experiment. J. Instrum. 13, T02007 (2018).

    Article  Google Scholar 

  26. Friedman, J. H. Greedy function approximation: a gradient boosting machine. Ann. Stat. 29, 1189–1232 (2001).

    Article  MathSciNet  Google Scholar 

  27. Agostinelli, S. et al. GEANT4: a simulation toolkit. Nucl. Instrum. Methods A 506, 250–303 (2003).

    Article  CAS  ADS  Google Scholar 

  28. Swiderski, L. Response of doped alkali iodides measured with gamma-ray absorption and Compton electrons. Nucl. Instrum. Methods A 705, 42–46 (2013).

    Article  CAS  ADS  Google Scholar 

  29. Caldwell, A., Kollár, D. & Kröninger, K. BAT – the Bayesian analysis toolkit. Comput. Phys. Commun. 180, 2197–2209 (2009).

    Article  CAS  ADS  Google Scholar 

  30. Alner, G. J. et al. Limits on WIMP cross-sections from the NAIAD experiment at the Boulby Underground Laboratory. Phys. Lett. B 616, 17–24 (2005).

    Article  CAS  ADS  Google Scholar 

  31. Adhikari, G. et al. The COSINE-100 data acquisition system. J. Instrum. 13, P09006 (2018).

    Article  Google Scholar 

  32. Sala, E. et al. Development of an underground low background instrument for high sensitivity measurements. J. Phys. Conf. Ser. 718, 062050 (2016).

    Article  Google Scholar 

  33. Pettus, W. C. Cosmogenic Activation in NaI Detectors for Dark Matter Searches. PhD thesis, Univ. Wisconsin–Madison (2015).

    Google Scholar 

Download references

Acknowledgements

We thank the Korea Hydro and Nuclear Power (KHNP) Company for providing underground laboratory space at Yangyang. This work is supported by: the Institute for Basic Science (IBS) under project code IBS-R016-A1 and NRF-2016R1A2B3008343, South Korea; UIUC campus research board, the Alfred P. Sloan Foundation Fellowship, NSF grant numbers PHY-1151795, PHY-1457995, DGE-1122492 and DGE-1256259, WIPAC, the Wisconsin Alumni Research Foundation, Yale University and DOE/NNSA grant number DE-FC52-08NA28752, USA; STFC grants ST/N000277/1 and ST/K001337/1, UK; and CNPq and grant number 2017/02952-0 FAPESP, Brazil.

Reviewer information

Nature thanks B. Sadoulet and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Author information

Author notes

  1. Antonia J. F. Hubbard

    Present address: Department of Physics and Astronomy, Northwestern University, Evanston, IL, USA

  2. Jungsic Park

    Present address: High Energy Accelerator Research Organization (KEK), Tsukuba, Japan

  3. Walter C. Pettus

    Present address: Center for Experimental Nuclear Physics and Astrophysics, Department of Physics, University of Washington, Seattle, WA, USA

  4. Andrew Scarff

    Present address: Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada

  5. A list of participants and their affiliations appears at the end of the paper.

Authors and Affiliations

  1. Department of Physics, Sejong University, Seoul, South Korea

    Govinda Adhikari, Pushparaj Adhikari & Yeongduk Kim

  2. Department of Physics, Yale University, New Haven, CT, USA

    Estella Barbosa de Souza, Antonia J. F. Hubbard, Jay Hyun Jo, Reina H. Maruyama, Walter C. Pettus & William G. Thompson

  3. Physics Institute, University of São Paulo, São Paulo, Brazil

    Nelson Carlin

  4. Department of Physics and Astronomy, Seoul National University, Seoul, South Korea

    Seonho Choi, Hanwool Joo & Sun Kee Kim

  5. Department of Physics, Bandung Institute of Technology, Bandung, Indonesia

    Mitra Djamal & Hafizh Prihtiadi

  6. Department of Physics and Astronomy, University of Sheffield, Sheffield, UK

    Anthony C. Ezeribe, Vitaly A. Kudryavtsev, Warren A. Lynch, Frederic Mouton, Andrew Scarff & Neil J. C. Spooner

  7. Center for Underground Physics, Institute for Basic Science (IBS), Daejeon, South Korea

    Chang Hyon Ha, Eunju Jeon, Woon Gu Kang, Bonghee Kim, Hyounggyu Kim, Kyungwon Kim, Nam Young Kim, Yeongduk Kim, Yong-Hamb Kim, Young Ju Ko, Hyun Su Lee, Jaison Lee, Moo Hyun Lee, Douglas S. Leonard, Stephen L. Olsen, Jungsic Park, Kangsoon Park, Sejin Ra, Keon Ah Shin & Seok Hyun Yong

  8. Department of Science Education, Ewha Womans University, Seoul, South Korea

    Insik Hahn

  9. Department of Physics, Sungkyunkwan University, Suwon, South Korea

    Woosik Kang & Carsten Rott

  10. Department of Physics and Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin-Madison, Madison, WI, USA

    Matthew Kauer

  11. Department of Physics, Kyungpook National University, Daegu, South Korea

    Hongjoo Kim & Jooyoung Lee

  12. Korea Research Institute of Standards and Science, Daejeon, South Korea

    Yong-Hamb Kim & Hyeonseo Park

  13. IBS School, University of Science and Technology (UST), Daejeon, South Korea

    Byungju Park

  14. Department of Accelerator Science, Korea University, Sejong, South Korea

    Hyang Kyu Park

  15. Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA

    Liang Yang

Consortia

The COSINE-100 Collaboration

  • Govinda Adhikari
  • , Pushparaj Adhikari
  • , Estella Barbosa de Souza
  • , Nelson Carlin
  • , Seonho Choi
  • , Mitra Djamal
  • , Anthony C. Ezeribe
  • , Chang Hyon Ha
  • , Insik Hahn
  • , Antonia J. F. Hubbard
  • , Eunju Jeon
  • , Jay Hyun Jo
  • , Hanwool Joo
  • , Woon Gu Kang
  • , Woosik Kang
  • , Matthew Kauer
  • , Bonghee Kim
  • , Hongjoo Kim
  • , Hyounggyu Kim
  • , Kyungwon Kim
  • , Nam Young Kim
  • , Sun Kee Kim
  • , Yeongduk Kim
  • , Yong-Hamb Kim
  • , Young Ju Ko
  • , Vitaly A. Kudryavtsev
  • , Hyun Su Lee
  • , Jaison Lee
  • , Jooyoung Lee
  • , Moo Hyun Lee
  • , Douglas S. Leonard
  • , Warren A. Lynch
  • , Reina H. Maruyama
  • , Frederic Mouton
  • , Stephen L. Olsen
  • , Byungju Park
  • , Hyang Kyu Park
  • , Hyeonseo Park
  • , Jungsic Park
  • , Kangsoon Park
  • , Walter C. Pettus
  • , Hafizh Prihtiadi
  • , Sejin Ra
  • , Carsten Rott
  • , Andrew Scarff
  • , Keon Ah Shin
  • , Neil J. C. Spooner
  • , William G. Thompson
  • , Liang Yang
  •  & Seok Hyun Yong

Contributions

Y.K., H.S.L., R.H.M. and N.J.C.S. conceived the COSINE-100 experiment. Its design and installation were led by K.P. and C.H.H. and carried out by all members of the collaboration. Operation and maintenance were organized by C.H.H. with support from on-site crews, W.G.K., B.K. and S.H.Y. Jaison Lee, J.P., J.H.J., G.A., P.A., H. Prihtiadi, C.H.H., W.G.T., E.B.d.S., H.S.L. and K.K. contributed to data acquisition, production and verification. H.J., Hyeonseo Park and K.K. provided nuclear recoil data. P.A., G.A., J.P., K.K., H. Prihtiadi, N.Y.K. and C.H.H. performed the source calibrations. Hyounggyu Kim, N.Y.K., C.H.H. and H.S.L. developed the slow control framework. J.H.J. and W.G.T. developed the data monitoring package. N.Y.K., Jooyoung Lee and Y.J.K. provided the radiopurity of the detector materials. G.A., J.P. and N.Y.K. produced the liquid scintillator. Background simulations were performed by F.M., E.J., P.A., W.G.T. and E.B.d.S. C.H.H. and P.A. analysed the observational and simulated data. The manuscript and plots were produced by C.H.H. and H.S.L., and edited by R.H.M., S.L.O., N.J.C.S. and the other members of the collaboration. All authors participated in online data-monitoring shifts and approved the manuscript. Authors are listed alphabetically by their last names.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended Data Fig. 1 The COSINE-100 detector.

a, The detector is contained within a nested arrangement of shielding components, as indicated by different colours. The main purpose of the shield is to provide 4π coverage against external radiation from various background sources. The shielding components include plastic scintillator panels (blue), a lead brick enclosure (grey) and a copper box (reddish brown). b, c, The eight encapsulated sodium iodide crystal assemblies (c) are located inside the copper box and are immersed in scintillating liquid (b). All images are schematic.

Extended Data Fig. 2 Typical waveforms from the COSINE-100 PMTs for 2–6-keV signals.

a, The β and γ scintillation signals have a fast rise and then fall off with a decay time of about 250 ns. The waveform from WIMPs is expected to closely resemble the β and γ waveforms. b, c, Background waveforms from PMT noise (b) and external discharge (c).

Extended Data Fig. 3 The BDT output (horizontal) versus the BDTA output (vertical).

a, b, Events (colour scale) with energies below 10 keV are shown for two separate crystals, with (a) and without (b) PMT discharge. The events to the right and above the red dotted lines are scintillation events induced by real particle–crystal interactions. PMT noise events are to the left of the vertical dotted lines in both panels; PMT discharge events are below the horizontal dotted line in a.

Extended Data Fig. 4 A comparison between data and simulation.

a–d, Four categories of data are shown: single-hit low-energy (2–70 keV; a); single-hit high-energy (70–3,000 keV; b); multiple-hit low-energy (2–70 keV; c); and multiple-hit high-energy (70–3,000 keV; d). The black points (with errors bars indicating the 68% confidence interval) are data. The green (yellow) band shows the ±1σ (±2σ) uncertainty range of the model. The peak near 3 keV in the multiple-hit, low-energy spectrum (c) is due to the tagged 40K events. The inset in a shows a zoomed-in view in the region of interest after efficiency corrections are applied. The major contributors to the radioactive background are labelled.

Extended Data Fig. 5 Crystal-by-crystal fit results.

a–f, The points (with errors bars indicating the 68% confidence interval) show the measured energy spectra for each of the six crystals. The fit results are shown as blue histograms, with the ±1σ (±2σ) error bands shown in green (yellow). To compare the signal strength of the DAMA sodium region with our data, a 10 GeV c−2 WIMP signal at 2.35 × 10−40 cm2 (the centre of the DAMA sodium region) is indicated for each crystal as a red histogram. The fit residuals, together with the expectations for the 10 GeV c−2 WIMP signal are also shown (bottom panels).

Source data

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

The COSINE-100 Collaboration. An experiment to search for dark-matter interactions using sodium iodide detectors. Nature 564, 83–86 (2018). https://doi.org/10.1038/s41586-018-0739-1

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41586-018-0739-1

Keywords

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing