The Korea Invisible Mass Search (KIMS; ), is a South Korean experiment searching for

weakly interacting massive particles Weakly interacting massive particles (WIMPs) are hypothetical particles that are one of the proposed candidates for dark matter. There exists no formal definition of a WIMP, but broadly, it is an elementary particle which interacts via gravity an ...

(WIMPs), one of the candidates for

dark matter In astronomy, dark matter is an invisible and hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravity, gravitational effects that cannot be explained by general relat ...

. The KIMS project was also named such as the three founders all have the surname

Kim Kim may refer to: People and fictional characters * Kim (given name), a list of people and fictional characters * Kim (surname), a list of people and fictional characters ** Kim (Korean surname) *** Kim dynasty (disambiguation), several dynas ...

; Kim Sun-kee, Kim Hongjoo, and Kim Yeongduk. The experiments use CsI( Tl) crystals at Yangyang Underground Laboratory (Y2L), in tunnels from a preexisting underground power plant. KIMS is supported by the Creative Research Initiative program of the Korea Science and Engineering Foundation. It is the first physics experiment located, and largely built, in Korea. Other research topics include detector development for a

neutrino A neutrino ( ; denoted by the Greek letter ) is an elementary particle that interacts via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass is so small ('' -ino'') that i ...

less double beta decay search and the creation of an extreme low temperature diamond

calorimeter A calorimeter is a device used for calorimetry, or the process of measuring the heat of chemical reactions or physical changes as well as heat capacity. Differential scanning calorimeters, isothermal micro calorimeters, titration calorimeters ...

History

The KIMS experiment was funded in 2000 to search for WIMP dark matter. To avoid the cost of creating a new tunnel for testing, the Yangyang Pumped Storage Power Plant belonging to Korea Middleland Power Co. in

Yangyang Yangyang County () is in Gangwon Province, South Korea. The county is located in the northeast of the country in Gangwon-do. Its population is about 31,000 (2004). The Yangyang area is well known for its pine mushrooms (''song-i''), its fish ...

, Korea was used. Construction was completed in 2003. The CsI(Tl) scintillating crystal used has a high light yield and is affordable for large mass. After a substantial effort for the initial setup and crystal development, KIMS began recording data in 2004 with one full-size 6 kg crystal. A 4 crystal setup was run in 2005–2006 to optimize the WIMP search. In 2008, the 12 crystal array with 103.4 kg mass was completed and ran until December 2012 for a detector upgrade replacing the PMTs.

Results

The first WIMP cross section search was published in 2006 using the one crystal data. New limits were presented in 2007 and 2012, inconsistent with the DAMA signal reports for masses above 20 GeV. Using 24,324.3 kg•days exposure, low-mass WIMP signals below 20 GeV were disfavored in 2014.

COSINE

The KIMS and DM-Ice groups collaborated to make a new detector consisting of an array of NaI(Tl) scintillating crystals to confirm or refute the

DAMA/LIBRA The DAMA/LIBRA experiment is a particle detector experiment designed to detect dark matter using the direct detection approach, by using a matrix of NaI(Tl) scintillation detectors to detect dark matter particles in the galactic halo. The ex ...

results. , the 100 kg COSINE-100 experiment had been installed at Y2L. In September 2016, physics data started to be collected. The next version of the COSINE detector, COSINE-200, will be constructed in

Yemilab Yemilab () is a subterranean dark matter research facility searching for weakly interacting massive particles and neutrinoless double beta decay and sterile neutrinos. The facility is 1,000 meters under the mountain Yemisan and encased in limesto ...

in Jeongseon County. The COSINE-100 published its first results on 5 December 2018 in ''

Nature Nature is an inherent character or constitution, particularly of the Ecosphere (planetary), ecosphere or the universe as a whole. In this general sense nature refers to the Scientific law, laws, elements and phenomenon, phenomena of the physic ...

''; they concluded that their result "rules out WIMP–nucleon interactions as the cause of the annual modulation observed by the DAMA collaboration". This rejection applies only to WIMPs with one of the 18 tested masses, exhibiting spin-independent interactions with sodium or iodine nucleons, within the context of a standard dark matter halo model. In November 2021, new results from COSINE-100 experiment from 1.7 years of data collection have also failed to replicate the signal of DAMA. In August 2022, COSINE-100 applied an analysis method similar to one used by DAMA/LIBRA and found a similar annual modulation suggesting the signal could be just an statistical artifact supporting an hypothesis first put forward on 2020.

References

External links

Official page (English)
{{Underground laboratories Experiments for dark matter search Science and technology in South Korea