In experiments at the Brookhaven National Lab in the U.S. , an outside team of physicist has detected the heavy “ anti - nuclei ” ever seen . The tiny , short - lived objects are composed of exotic antimatter particle .
The mensuration of how often these entity are produced and their prop corroborate our current reason of the nature of antimatter , and will help the search for another mysterious form of particle — dark matter — in deep space . The results werepublished earlier this month inNature .
A missing mirror world
The idea of antimatter is less than a century old . In 1928 , British physicist Paul Dirac make grow a very exact theory for the behaviour of electrons that made a distressful prediction : the existence of electrons with electronegative energy , which would have made the stable creation we know in impossible .
as luck would have it , scientists found an alternative explanation for these “ electronegative energy ” commonwealth : antielectrons , or twin of the negatron with the paired electric charge . Antielectrons were punctually discovered in experiment in 1932 , and since then scientist have establish that all fundamental particles have their own antimatter combining weight .
However , this upgrade another question . antielectron , antiprotons and antineutron should be able to combine to make whole antiatoms , and indeed antiplanets and antigalaxies . What ’s more , our hypothesis of the Big Bang suggest equal amount of matter and antimatter must have been create at the beginning of the universe .
The relativistic heavy ion collider at Brookhaven National Laboratory.Image: Brookhaven National Laboratory
But everywhere we count , we see matter — and only insignificant amounts of antimatter . Where did the antimatter go ? That is a question that has vexed scientists for nearly a C .
Fragments of smashed atoms
Today ’s resultant come from theSTAR experiment , site at theRelativistic Heavy Ion Colliderat Brookhaven National Lab in the U.S. The experiment works by smashing the core of heavy component such as atomic number 92 into one another at extremely high-pitched speed . These collisions produce tiny , acute fireballs which briefly repeat the conditions of the cosmos in the first few msec after the Big Bang .
Each collision produces hundreds of newfangled speck , and the STAR experimentation can detect them all . Most of those atom are abruptly - lived , unstable entities holler pions , but ever so occasionally something more interesting turns up .
In the STAR detector , particles zoom through a orotund container full of gas inside a magnetic field — and give visible trails in their Wake Island . By measuring the “ heaviness ” of the trails and how much they turn away in the magnetic field , scientists can work out what variety of particle give rise it . Matter and antimatter have an opposite mission , so their route will bend in opposite directions in the magnetic field .
‘Antihyperhydrogen’
In nature , the nuclei of corpuscle are made of protons and neutrons . However , we can also make something called a “ hypernucleus ” , in which one of the neutrons is replaced by a hyperon — a slightly sound version of the neutron .
What they detected at the STAR experiment was a hypernucleus made of antimatter , or an antihypernucleus . In fact , it was the heaviest and most exotic antimatter nucleus ever seen .
To be specific , it lie of one antiproton , two antineutron and an antihyperon , and has the name of antihyperhydrogen-4 . Among the billions of pi-meson produce , the STAR researchers identified just 16 antihyperhydrogen-4 core group .
Results confirm predictions
The new paper compare these Modern and heavy antinuclei as well as a host of other wakeful antinuclei to their vis-a-vis in normal matter . The hypernuclei are all unstable and decay after about a one-tenth of a nanosecond .
Comparing the hypernuclei with their corresponding antihypernuclei , we see that they have identical lifetimes and masses — which is exactly what we would expect from Dirac ’s theory . Existing theories also do a dear job of predicting how scant antihypernuclei are produced more often , and heavier ones more rarely .
A shadow world as well?
Antimatter also has fascinating links to another alien inwardness , dark matter . From reflection , we roll in the hay blue matter sink in the universe and is five times more dominant than normal thing , but we have never been able to detect it directly .
Some theories of dark matter predict that if two dingy matter particles collide , they will carry off each other and produce a burst of subject and antimatter particles . This would then produce antihydrogen and antihelium , and an experiment call theAlpha Magnetic Spectrometeraboard the International Space Station is looking out for it .
If we did watch over antihelium in space , how would we know if it had been produced by dark subject or normal matter ? Well , measurements like this new one from STAR allow us calibrate our theoretical models for how much antimatter is produced in collision of normal subject . This a la mode theme furnish a wealth of data point for that type of standardisation .
Basic questions remain
We have learn a lot about antimatter over the preceding century . However , we are still no closer to answering the interrogation of why we see so little of it in the universe .
The STAR experiment is far from alone in the seeking to understand the nature of antimatter and where it all went . cultivate at experiment such asLHCbandAliceat theLarge Hadron Colliderin Switzerland will raise our apprehension by take care for signs of difference in behaviour between matter and antimatter .
Perhaps by 2032 , when the centenary of the initial find of antimatter rolls around , we will have made some strides in interpret the position of this curious mirror matter in the macrocosm — and even eff how it is connect the enigma of dark matter .
Ulrik Egede is ais a professor of physics atMonash University . This clause is republish fromThe Conversationunder a Creative Commons permission . Read theoriginal article .
AntimatterDark matterParticle physics
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