4/21/2015 www.hngn.com/home/news/services/print.php?article_id=86269

http://www.hngn.com/home/news/services/print.php?article_id=86269 1/1

Print

ByRebekahMarcarelli | r.marcarelli@hngn.com | 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.