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4/21/2015 www.hngn.com/home/news/services/print.php?article_id=86269
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ByRebekahMarcarelli | [email protected] | Apr21,201503:31PMEDT
TabletopParticleDetectorCouldLeadToCovetedNeutrinoMassMeasurement
Scientistsdevelopedanewtabletopparticledetectorthatcanidentifysingleelectronsinradioactivegas.
Asthisgasdecaysitemitselectronsthatcanbetrappedbyamagneticbottle,andaradioantennacanpickoffsignalsgivenoffbythesecaptiveelectrons,MITreported.Thistechniquecanallowresearcherstomaptheelectrons'preciseactivityoverseveralmilliseconds.
Thenovelmethodallowedaresearchteamtorecordtheactivityof100,000individualelectronsinkryptongas.Mostoftheseobservedelectronsbehavedinacharacteristicpatternasthegasdecaysitemitsvibratingelectronsthatslowlycalmdownbeforespikingagaininfrequencywhenhitwithmoregasatoms.Astheelectrons"pingpong"againstatomsinthedetector,theirenergyprogressesinasteplikepattern.
"Wecanliterallyimagethefrequencyoftheelectron,andweseethiselectronsuddenlypopintoourradioantenna,"saidJoeFormaggio,anassociateprofessorofphysicsatMIT."Overtime,thefrequencychanges,andactuallychirpsup.Sotheseelectronsarechirpinginradiowaves."
Themethodcouldhelpscientistsaccomplishanevengreaterfeatmeasuringthemassoftheelusiveneutrino.These"ghostly"passthroughthebodyingroupsofbillionseverysecond,butareyettobeconcretelydetected.Scientistshavesettheoreticallimitsonaneutrino'smass,butarestillfindingdifficultygainingmoreinsightintotheseparticles.
"Wehave[themass]cornered,buthaven'tmeasuredityet,"Formaggiosaid."Thenameofthegameistomeasuretheenergyofanelectronthat'syoursignaturethattellsyouabouttheneutrino."
Whenaradioactiveatomdecays,itturnsintoanisotopeofheliumandreleasesanelectronandaneutrinotheenergyofallparticlesaddsuptothetotalenergyoftheparentneutrino.Thismeansthatmeasuringtheenergyoftheelectroncanrevealthemassoftheneutrino.
ResearchershopemeasureelectronsintheradioactiveatomtritiumusingamassivespectrometeraspartofanexperimentnamedKATRIN(KarlsruheTritiumNeutrinoExperiment).
"InKATRIN,theelectronsaredetectedinasilicondetector,whichmeanstheelectronssmashintothecrystal,andalotofrandomthingshappen,essentiallydestroyingtheelectrons,"saidDanielFurse,agraduatestudentinphysics,andacoauthoronthepaper."Westillwanttomeasuretheenergyofelectrons,butwedoitinanondestructiveway."
Thisnewsetupgivestheresearchersavaluableadvantagebecauseofitstinytabletopsize'incontrast,KATRIN'sspectrometercouldbarelyfitthroughacitystreet.Basedontheprecisionofmeasurementthedevicedemonstratedwithkryptongas,thesamecouldbeachievedwithtritiumwithinthenexttwoyears,potentiallyresultinginanaccuratemeasurementofthemassofaneutrino.
ThefindingswerepublishedinarecenteditionofthejournalPhysicalReviewLetters.