A mystifying signal has appeared in an extremely raw drab matter - hunting experimentation . And after more than a year of test to convince themselves that they were attend at disturbance , scientists think they might have found something new .
Today , the scientists behind the XENON1 T dark topic experiment are reporting the answer of a hunt through its data for mote that interact with the electrons in its detecting medium . They ’ve spotted evidence of an excess , or more interaction with the detector than the Standard Model of particle aperient would predict . They do n’t know what ’s causing the signal yet ; it might be a rare but mundane issue , or it could be evidence of some other unknown purgative phenomenon .
“ We were wreck our encephalon around what it could be , ” Laura Baudis , University of Zurich particle astrophysicist , tell Gizmodo . She explained that University of Zurich researcher Michelle Galloway rest up late into the Nox in rescript to put to work alongside University of Chicago graduate pupil Evan Shockley and University of California , San Diego pupil Jingqiang Ye on completing the analysis .
The three-story XENON experiment and its service building (see humans for scale at bottom right).Photo: XENON collaboration
XENON1 T is an experimentation containing 3.2 metric tons of the element xenon , swallow up deep inside a wad at the INFN Laboratori Nazionali del Gran Sasso in Italy , which pull together data from 2016 to 2018 . The experimentation sits in wait for particles that barely interact with thing to cause a slight knock to the xenon core group or their electrons , releasing diminutive flashes of light detected by sensors in the wall of the experimentation . The XENON collaboration ’s scientists go for to reveal the truthful personal identity of glowering thing , the orphic stuff whose gravitational attraction seems to service as the macrocosm ’s staging but that our molecule physical science theoriesfail to explain . Up until now , the experiment ’s datahaven’trevealedany newfangled physical phenomena .
But XENON1 T data point ingest from February 2017 to February 2018 has revealed an unexpected overindulgence of miserable - Department of Energy interactions with the xenon ’s electrons—285 events instead of the await 232 event , according to the paper stake today on theXENON1 T website .
physicist have theorize various likely sources of the overabundance , essay their approximation against the data . They come at three most likely reservoir : Perhaps an unobserved , theoretical particle call an axion struck the detector after traveling from the Sun . Maybe a property of theneutrino particle , called its magnetized moment , is higher than previously forecast . Or , perhaps they ’d simply spotted an unaccounted - for screen background radioactive process , the decay of the atomic number 1 isotope called tritium . Just a few tritium atoms sprinkled into the two tons of otherwise ultra - arrant xenon could have farm the signal .
Axions are a theorized , low - mint particle imply to solve a physics trouble called the strong - CP problem , which asks why subatomic particles shout quarks keep up the same laws of natural philosophy when you replace them with their mirror range with the opposite thrill , when there ’s no reason that they have to . If axions did be , then scientists predict that the Sun would get them in its magnetic core , and we ’d be possibly be capable to detect them from Earth . Axions are also a proposed perpetrator to explain at least some of sullen matter .
Solar axions passing through the detector would search most like the signal that the research worker observe , with a 3.5 - sigma significance , meaning that there ’s a 99.98 % chance that the discovered signaling was n’t due to distinctive physics processes . However , introducing tritium decay as another background process minify the significance to 2 sigma , or a 95 % probability that typical physics interaction plus decaying tritium did n’t cause the signaling , Baudis said . More data could easy wipe out such a wavering andhas in the past . Particle physicists strive for a 5 - sigma signification in society to proclaim a discovery .
Other physicists were impressed with the amount of work and thought that went into the analyses and with the extreme sensitivity of the detector — but they inspire caution with rendition of the results . “ They ’ve done a hugely effective Book of Job of sympathize their background , ” Bob Jacobsen , University of California , Berkeley prof not take in this work , told Gizmodo . But he point out that there simply is n’t a flock of data to expect at here . “ It ’s just really interesting hints . ”
Javier Redondo , physicist at the University of Zargoza in Spain , told Gizmodo in an electronic mail that the signal looked just like solar axions were top through XENON1T. However , he said , if hypothetical axion particles produced by the Sun were to create this signal , then it imply a strong fundamental interaction between axions and electron than theory predict today .
“ Even our Sun would not agree with the best theoretical models and experiments as well as it does now , ” he order . The solar axion properties implied by the XENON1 thymine experiment would ensue in the Sun being hot than astronomers predict and producing far more neutrino than stargazer observe . He said that in order for the psychoanalysis to convince him that solar axions were causing the excess , he ’d want to see a smoke - throttle theme song , such as solar axions appear in dedicated experimentation calledsolar magnetized helioscopes . Perhaps some other , unidentified mote is causing the signal , he order .
Uncovering the true cause of the signal will take more work . A suite of standardized experiments , such as the LZ experiment at the Sanford Underground Research Facility in South Dakota and PandaX at the China Jinping Underground Laboratory in Sichuan , China , will likely follow with their own analysis to see if they find out the same signal . The XENON1 T experiment will soon get an upgrade to become XENONnT — now with even more melted xenon — after which physicists can repeat this analysis . XENONnT and solar magnetic helioscopes should be able to spot and explicate this sign more easily , if the signal holds , of line . “ There ’s a circumstances of ifs , ” Baudis said .
Such is the way of aperient ; sometimes , the most interesting sign lie down at the furthest reaches of an experiment ’s sensitivity and do n’t occur often enough for physicists to claim a breakthrough . While we all hope that these signals will flex out to be some unexplained feature film of the universe of discourse , sometimes , they ’re just the average decay of a distich of pesky radioactive atoms . At the mo , physicists do n’t know what they ’re looking at . All they can say is that it ’s definitely interesting .
sinister matterParticle physicsScience
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