physicist have been judge for several years to twofold - contain a sign from an experiment buried in an Italian mountain — a signaling that looked an awful lot like a dark issue suspect known as a crybaby . former attempts to see that signal with other projects had fallen matte , and now , the experiment most similar to the original one has published its results : It , too , find nothing .
No one knows what dark thing is — it ’s a procurator term used to report the invisible stuff we can only detect via its gravity — but one candidate to explain dark matter is call WIMPs , or Weakly Interacting Massive Particles . The idea is that some subatomic particles do have mass but interact so weakly with average matter that we ’ve yet to notice them . the great unwashed mostly search for WIMPs by put passing sensitive detector deep in the ground , where they are harbour from many of the influence that might produce misleading signaling .
The experiment that purportedlydetected a WIMP signal in 2017is the DAMA / Balance experiment . DAMA / LIBRA apply sodium iodide lechatelierite as targets for dark subject ; the idea is that if gloomy matter pass through the lechatelierite , they ’ll get emotional and become a little bright . Other experimentation that search for WIMP by other mean , like the XENON1 T in Italy and XMASS - I in Japan , havenot been able to findthe signal that DAMA / LIBRA is seeing .
Crystal detectors in the COSINE-100 experiment.Illustration: COSINE-100 Collaboration
accede theCOSINE-100 experimentation , which is based in a laboratory 2,300 feet underground in South Korea . COSINE-100 utilise over 200 pounds of the same sodium iodide aim , making it a near mimic of DAMA / LIBRA . COSINE-100 has been looking for a WIMP signal since 2016 . Its first search change state up zilch . Its next search , the results of which arepublishedtoday in Science Advances , run from October 2016 through July 2018 . The COSINE-100 team reported that they establish just as little as they did last time , which could entail the end of the route for the controversial DAMA / LIBRA results .
“ Our squad found that what DAMA observed could not be the dark matter under most canonical assumptions of how we cerebrate WIMPs should interact with ordinary topic , ” Reina Maruyama , a physicist at Yale University and a co - author of the recent paper , told Gizmodo in an electronic mail . “ We have not yet strongly try DAMA ’s observation of annual inflection , which DAMA argue is due to dark matter . That is our next focus . ”
DAMA / LIBRA apply a different overture to test to detect glum thing than most experiments . While other setups either look for dark matter particles by colliding known particles or looking for a background signal , DAMA / LIBRA has maintain the even intonation of some unexplained sign that Earth has received in different amounts , depending on how it ’s oriented , since the experimentbegan operation in 2003 . Other task have bomb to see the same signal , which is in the X - ray band of the electromagnetic spectrum . But , perhaps due to the agency the experimentation get by its noise , as reported by Ethan Siegel in Forbes , the DAMA / LIBRA folks may have been seeing a signaling where there was n’t one to start with .
An artist’s mock-up of a WIMP being detected in the experiment.Illustration: COSINE-100 Collaboration
The COSINE-100 newspaper “ does not exchange at all the sorry issue probe , ” sound out DAMA / LIBRA spokesperson Rita Bernabei , a physicist at Italy ’s National Institute for Nuclear Physics and the University of Rome Tor Vergata . “ view that so many model are possible about related astrophysical , atomic and particle natural philosophy aspects and the many exist uncertainties on related parameters and assumptions , a serious comparison is quite a complicated and unsettled job both from experimental and theoretical points . ”
Bernabei emphasized that the two detectors are not the same and that the COSINE-100 team ’s method can produce “ gravid uncertainties and prejudice . ”
“ Although our results do not prefer the morose matter rendition of DAMA assuming the most wide used dark matter model , we could not say DAMA is nothing , ” said Hyun Su Lee , a co - author of the recent paper and a physicist at the Center for Underground Physics at the Institute for Basic Science in South Korea , in an email to Gizmodo . In other Christian Bible , DAMA has some sort of signal , but COSINE-100 results suggest it was not dark matter .
Crystal detectors in the COSINE-100 set-up.Photo: COSINE-100 Collaboration
Some physicists , like Dan Hooper at the University of Chicago , do experience that the newer experiment has done a good job of showing that the DAMA / LIBRA experiment is not the style we ’ll find wimp , if they exist .
“ My perspective is that over the past 10 to 15 years , it has steady become more and more unmanageable to think that the sign being account by the DAMA collaboration was really the consequence of dark matter particles . One after the other , experiment came out with results that failed to sustain the claim of DAMA , ” Hooper said in an email . “ Most of the physicist I know ( including myself ) essentially give up on this possible action years ago . ”
“ That being allege , we all harmonize that it would be most convincing if an experiment could be carried out that used exactly the same kind of object textile that DAMA used , ” Hooper added . “ The COSINE experiment is on the button that , and the fact that they did not see anything is really a big nail in the casket of dark matter version of DAMA . I still do n’t make out what it is that DAMA is realise — maybe it ’s some weird background , or just some mistake they ’ve somehow made . But whatever is going on , it does n’t seem to have anything to do with dismal subject . ”
WIMPs have been lose steamas the forerunning dark matter campaigner . Axions — much smaller particles — have become a hotter topic in late year , and even huge objective like primaeval black holes remain a possibility in some roundabout . No one has been able to attest any direct sleuthing of dark matter yet , but heap of experiments are looking in different blank .
“ I am excited to see what we regain with the large WIMP experiments like XENONnT , LZ , and SuperCDMS , ” Maruyama say . “ I also find axions compelling and am excited to be run on HAYSTAC and its extension . With COSINE , we can proceed to search for weakly interacting massive particle and of course , the next steps are to carry out the ultimate mental test of DAMA — annual transition . ” The annual modulations are that unearthly signal itself , which ebbs and flows over the form of each twelvemonth . Just because it ’s not dark issue does n’t mean it ’s not intriguing .
In purgative , find nothing can be just as illuminating as finding something ; in the case of blue affair , it can order scientists that they need to expect elsewhere .
More : If We exist in a Sea of Dark Matter , This Tiny Mirror Might Be Able to find It
Dark matterParticle physicsPhysical sciencesPhysicstheoretical physics
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