neutrino 中微子调研

CompanyLOGOContentsThefindingofneutrino1Neutrinoproperties2Superluminality3Future4TaishancollegePhysicsmajorThefindingofneutrinoIn1930,Paulimadehisfamoussuggestion.Beforethatpeoplehadfoundenergynon-conservationinβ-decay.ButPaulistucktotheideathatenergyconservationwasviolatedeveninβdecay.Paulisuggestednewparticleexertedinβdecay.Andhenameditneutrino.PeoplecalleditasPauli’sneutrinohypothesis.（WolfgangE.Pauli，1900～1958）TaishancollegePhysicsmajorThefindingofneutrinoIn1933,FermibelievedPauli’sneutrinohypothesis.Heformulatedaquantitativetheory,whichhepublishedbrieflyinRicercaScientificalatein1933andinZeitsf.Physikearlyin1934.（EnricoFermi，1901-1954）TaishancollegePhysicsmajorThefindingofneutrino（JamesChadwick，1891～1974）MorecarefulExperimentsweredonetryingtodetectneutrinoseg.thatofChadwickandLeewhoconcludedtheneutrinomusthaveasmallmass.T.D.LeeTaishancollegePhysicsmajorThefindingofneutrinoIn1940-1941,WangGanchangpublishedanarticleaboutthesuggestionthatusingK-capturetomeasurerecoilenergytoprovetheexistenceofneutrinos.In1942.6,anAmericanphysicistAllenprovedtheexistenceofneutrinosusingthesuggestions.Buttheexperimentwasnotreallysuccessful.WangGanchangTaishancollegePhysicsmajorThefindingofneutrinoIn1956,AmericanphysicistsC.L.CowanandReinesFrederichfirstdetectedtheneutrinosdirectly.ReinesFrederichTaishancollegePhysicsmajorThefindingofneutrino1968RayDavisandcolleaguesgetfirstradiochemicalsolarneutrinoresultsusingcleaningfluidintheHomestakeMineinNorthDakota,leadingtotheobserveddeficitknownasthesolarneutrinoproblem.RayDavisTaishancollegePhysicsmajorTaishancollegePhysicsmajorThefindingofneutrinoWaystoemitneutrinosTaishancollegePhysicsmajoreeVAZAZeVeAZAZ),(),1(),1(),(VVAZAZe),(),1(VVeeVVeeWaystoemitneutrinosTaishancollegePhysicsmajorBetadecayInnuclearPhysics,betadecayisatypeofradioactivedecayinwhichabetaparticle(anelectronorapositron)isemittedfromanatom.Therearetwotypesofbetadecay:betaminusandbetaplus.Inthecaseofbetadecaythatproducesanelectronemission,itisreferredtoasbetaminus(β−),whileinthecaseofapositronemissionasbetaplus(β+).Inelectronemission,anelectronantineutrinoisalsoemitted,whilepositronemissionisaccompaniedbyanelectronneutrino.Betadecayismediatedbytheweakforce.TaishancollegePhysicsmajorBetadecayβ−decayInβ−decay,theweakinteractionconvertsaneutron(n)intoaproton(p)whileemittinganelectron(e−)andanelectronantineutrino(νe):evepnβ−decaygenerallyoccursinneutronrichnucleiTaishancollegePhysicsmajorBetadecayβ+decayInβ+decay,energyisusedtoconvertaprotonintoaneutron,whileemittingapositron(e+)andanelectronneutrino(νe):TaishancollegePhysicsmajorevenpenergySounlikeβ−,β+decaycannotoccurinisolationbecauseitrequiresenergy,themassoftheneutronbeinggreaterthanthemassoftheproton.β+decaycanonlyhappeninsidenucleiwhenthevalueofthebindingenergyofthemothernucleusislessthanthatofthedaughternucleus.Thedifferencebetweentheseenergiesgoesintothereactionofconvertingaprotonintoaneutron,apositronandaneutrinoandintothekineticenergyoftheseparticles.BetadecayDoublebetadecaySomenucleicanundergodoublebetadecay(ββdecay)wherethechargeofthenucleuschangesbytwounits.Doublebetadecayisdifficulttostudyinmostpracticallyinterestingcases,becausebothβdecayandββdecayarepossible,withprobabilityfavoringβdecay;therarerββdecayprocessismaskedbytheseevents.Thus,ββdecayisusuallystudiedonlyforbetastablenuclei.TaishancollegePhysicsmajorpropertiesSpinSuperluminalityNeutrinooscillationNeutrinoPropertiesTaishancollegePhysicsmajorPropertiesNeutrinosdonotcarryelectriccharge,whichmeansthattheyarenotaffectedbytheelectromagneticforcesthatactonchargedparticlessuchaselectronsandprotons.Neutrinosareaffectedonlybytheweaksub-atomicforce,ofmuchshorterrangethanelectromagnetism,andgravity,whichisrelativelyweakonthesubatomicscale,andarethereforeabletotravelgreatdistancesthroughmatterwithoutbeingaffectedbyit.TaishancollegePhysicsmajorPropertiesSpinNeutrino’sspinquantumnumberis1/2andhasnostronginteractionashadron.Asforspinquantumnumber,whensubstances’spinquantumnumberis1/2,thenwecansaythatallkindsofsubstancesconsistofthatkindofsubstance.Asneutrino’sinteractionisreallyfeeblewhichisthesameasDarkmatter,thenpeopleregardtheneutrinoasakindofDarkmatter.TaishancollegePhysicsmajorThreetypesofneutrinoeTheelectronneutrino(νe)isasubatomicleptonelementaryparticlewhichhasnonetelectricchargeμThemuonneutrinoisasubatomicleptonelementaryparticlewhichhasthesymbolνμandnonetelectricchargeThetauneutrinoortauonneutrinoisasubatomicelementaryparticlewhichhasthesymbolντandnonetelectriccharge.τTaishancollegePhysicsmajorPauseFindinghistoryBetadecayNeutrinooscillationTaishancollegePhysicsmajorNeutrinooscillationNeutrinooscillationSolarneutrinooscillationAtmosphericneutrinooscillationReactorneutrinooscillationBeamneutrinooscillationTaishancollegePhysicsmajorNeutrinooscillationTheoryNeutrinooscillationarisesfromamixturebetweentheflavorandmasseigenstatesofneutrinos.Thatis,thethreeneutrinostatesthatinteractwiththechargedleptonsinweakinteractionsareeachadifferentsuperpositionofthethreeneutrinos