Yale scientists are a part of a brand new worldwide experiment that challenges earlier claims concerning the detection of non-luminous darkish matter.
Astrophysical proof means that the universe accommodates a considerable amount of non-luminous darkish matter, but no particular sign of it has been noticed regardless of concerted efforts by many experimental teams. One exception to that is the long-debated declare by the DArk MAtter (DAMA) collaboration, which has reported optimistic observations of darkish matter in its sodium-iodide detector array.
The brand new COSINE-100 experiment, primarily based at an underground, dark-matter detector on the Yangyang Underground Laboratory in South Korea, has begun to discover DAMA’s declare. It’s the first experiment delicate sufficient to check DAMA and use the identical goal materials of sodium iodide.
COSINE-100 has been recording information since 2016 and now has preliminary outcomes that problem the DAMA findings. These findings are printed on-line this week within the journal Nature.
“For the primary time in 20 years, we’ve an opportunity to resolve the DAMA conundrum,” mentioned Yale physics professor Reina Maruyama, who’s co-spokesperson for COSINE-100 and co-author of the brand new research.
The primary part of COSINE-100’s work searches for darkish matter by searching for an extra of sign over the anticipated background within the detector, with the fitting power and traits. On this preliminary research, the researchers discovered no extra of sign in its information, placing DAMA’s annual modulation sign at odds with with outcomes from different experiments. COSINE-100 scientists famous that it’ll take a number of years of knowledge to completely verify or refute DAMA’s outcomes.
The COSINE-100 experiment makes use of eight low-background, thallium-doped sodium iodide crystals organized in a 4-by-2 array, giving a complete goal mass of 106 kg. Every crystal is coupled by two picture sensors to measure the quantity of power deposited within the crystal.
The sodium iodide crystal assemblies are immersed in 2,200 L of light-emitting liquid, which permits for the identification and subsequent discount of radioactive backgrounds noticed by the crystals. The detector is contained inside a nested association of copper, lead, and plastic shielding parts to cut back the background contribution from exterior radiation, in addition to cosmic ray muons.
The COSINE-100 collaboration consists of 50 scientists from the U.S., South Korea, the UK, Brazil, and Indonesia. The Yangyang Underground Laboratory, the place the experiment relies, is operated by the Middle for Underground Physics of the Institute for Fundamental Science (IBS) in South Korea.
“The preliminary outcomes carve out a good portion of the doable darkish matter search area drawn by the DAMA sign. In different phrases, there’s little room left for this declare to be from the darkish matter interplay until the darkish matter mannequin is considerably modified,” mentioned Hyun Su Lee, the opposite co-spokesperson for COSINE-100, and an affiliate director of the Middle for Underground Physics at IBS.
Members of the group from Yale’s Division of Physics and Wright Laboratory embody Maruyama, postdoctoral affiliate Jay Hyun Jo, graduate college students Estella Barbosa de Souza and William Thompson, and undergraduate college students Elizabeth Ruddy and Daniel Heimsoth.
The experiment is supported by IBS and the Nationwide Science Basis. Further assist comes from Yale College.
For extra details about COSINE-100, go to Yale’s COSINE-100 web site or the project website at the Institute for Basic Science.
Publication: The COSINE-100 Collaboration, “An experiment to seek for dark-matter interactions utilizing sodium iodide detectors,” Nature volume 564, pages 83–86 (2018)