简介：Inthescenariowherethedarkmatter(DM)particlesχχˉpairannihilatethrougharesonanceparticleR,theconstraintfromDMrelicdensitymakesthecorrespondingcrosssectionforDM-nucleielasticscatteringextremelysmall,andcanbebelowtheneutrinobackgroundinducedbythecoherentneutrino-nucleiscattering,whichmakestheDMparticlebeyondthereachoftheconventionalDMdirectdetectionexperiments.WepresentanimprovedanalyticalcalculationoftheDMrelicdensityinthecaseofresonantDMannihilationfors-andp-wavecasesandinvesitgatetheconditionfortheDM-nucleiscatteringcrosssectiontobeabovetheneutrinobackground.WeshowthatinHiggs-portaltypemodels,forDMparticleswiths-waveannihilation,thespin-independentDM-nucleusscatteringcrosssectionisproportionaltoΓR/mR,theratioofthedecaywidthandthemassofR.ForatypicalDMparticlemass～50GeV,theconditionleadstoΓR/mR≥O(10-4).Inp-waveannihilationcase,thespin-independentscatteringcrosssectionisinsensitivetoΓR/mR,andisalwaysabovetheneutrinobackground,aslongastheDMparticleislighterthanthetopquark.TherealsingletDMmodelisdiscussedasaconcreteexample.

简介：正电子歼灭一生光谱学(伙伴)是一种强大的技术在聚合物学习免费体积。ortho电子偶素(o-Ps)的一生，一个电子的一个界限状态和一个正电子，当紧张能被用来描绘毛孔的数字时，能被用来估计毛孔尺寸。(2,6-dimethyl-1,4-phenyleneoxide)(SPPO)根据在在sulfonated的一生系列，半径和部分免费体积的长寿o-Ps部件的价值，poly，有LiCl的不同数量的膜被计算。与LiCl的增加的数量，免费体积半径和部分免费体积第一增加了然后减少，这被发现。在在提取的水里沉浸膜以后，免费体积半径和部分免费体积在膜随着不同的水集中变化了。

简介：Ananalysisprogramforpositronannihilationlifetimespectraisonlyapplicabletoisolateddefects,butisofnouseinthepresenceofdefectivecorrelations.Suchlimitationshavelongcausedproblemsforpositronresearchersintheirstudiesofcomplicateddefectivesystems.Inordertosolvethisproblem,weaimtotakeasemiconductormaterial,forexample,toachieveacredibleaveragelifetimeofsinglecrystalsiliconunderplasticdeformationatdifferenttemperaturesusingpositronlifetimespectroscopy.Byestablishingreasonablepositrontrappingmodelswithdefectivecorrelationsandsortingoutfourlifetimecomponentswithmultipleparameters,aswellastheirrespectiveintensities,informationisobtainedonthepositrontrappingcenters,suchasthepositrontrappingratesofdefects,thedensityofthedislocationlinesandcorrelationbetweenthedislocationlines,andthevacancydefects,byfittingwiththeaveragelifetimewiththeaidofMatlabsoftware.Theseresultsgivestronggroundsfortheexistenceofdislocation-vacancycorrelationinplasticallydeformedsilicon,andlayatheoreticalfoundationfortheanalysisofpositronlifetimespectrawhenthepositrontrappingmodelinvolvesdislocation-relateddefects.

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简介：Inthepaper,theauthorsanalysetherela-tionshipbetweentheelectricalconductivityσofZrO2andthecontentofdopedstabilizingagentbythePositronAnnihilationTechnique,andexplainthechangetendencyofσwiththecontentofstabilizingagent.Theresearchshowsthat"numberofeffectivevacancy"inmaterialisadecisivefactorcausingchangeofσ.

简介：ByusingthegeneralizedDebyediffractionintegral,thispaperstudiesthespatialcorrelationpropertiesandphasesingularityannihilationofaperturedGaussianSchell-model(GSM)beamsinthefocalregion.Itisshownthatthewidthofthespectraldegreeofcoherencecanbelarger,lessthanorequaltothecorrespondingwidthofspectraldensity,whichdependsnotonlyonthescalarcoherencelengthofthebeams,butalsoonthetruncationparameter.Withagradualincreaseofthetruncationparameter,apairofphasesingularitiesofthespectraldegreeofcoherenceinthefocalplaneapproacheseachother,resultinginsubwavelengthstructures.Finally,theannihilationofpairsofphasesingularitiestakesplaceatacertainvalueofthetruncationparameter.Withincreasingscalarcoherencelength,theannihilationoccursatthelargertruncationparameter.However,thecreationprocessofphasesingularitiesoutsidethefocalplaneisnotfoundforGSMbeams.

简介：Amapoftheaverageatomicnumberoflunarrockandsoilcanbeusedtodifferentiatelithologyandsoiltypeonthelunarsurface.Thispaperestablishesalinearrelationshipbetweentheaverageatomicnumberoflunarrockorsoilandthefluxofpositionannihilationradiation(0.512-MeVgamma-ray)fromthelunarsurface.TherelationshipisconfirmedbyMonteCarlosimulationwithdatafromlunarrockorsoilsamplescollectedbyLuna(Russia)andApollo(USA)missions.AmapoftheaverageatomicnumberofthelunarrockandsoilonthelunarsurfacehasbeenderivedfromtheGamma-RaySpectrometerdatacollectedbyChang’e-1,anunmannedChineselunar-orbitingspacecraft.Inthemap,thehigheraverageatomicnumbers(ZA>12.5),whicharerelatedtodifferenttypesofbasalt,areinthemariaregion;thehighestZA(13.2)readingsareassociatedwithSinusAestuum.ThemiddleZA(~12.1)regions,intheshapeofirregularovalrings,areinWestOceanusProcellarumandMareFrigoris,whichseemstobeconsistentwiththedistributionofpotassium,rareearthelements,andphosphorusasauniquefeatureonthelunarsurface.Theloweraverageatomicnumbers(ZA<11.5)arefoundtobecorrelatedwiththeanorthositeonthefarsideoftheMoon.

简介：PositronannihilationtechniquewasusedtostudythemicellebehaviorsoftwoSBStriblockcopolymersinMEKsolventatdifferenttemperatures.Annihilationlifetimeτ3ofortho-positronium（o-Ps）exhibitedanobvioustransitionfromshorterlifetimetolongerlifetimewithtemperature.ItwasattributedtothechangeofmicellebehaviorofSBScopolymermoleculesinthesolution.Experimentalresultsofsedimentationvelocityofultracentrifugewerealsoreported.

简介：Withpositronannihilationradiationonedimensionangular-correlationdevice,itismeasuredthatpositronannihilationradiationonedimensionangular-correlationcurvesofpolycrystalsodiumionconductorNa5Y1-xCrxSi4O12（NYCS）system.Afterelectronmomentumdistributioncurvesarenormalized,linearparametersarecalculated.TheparametersH,WandSshowthechangeofNa+ionvacancyconcentrationinNYCSseriessamples.TheresultsshowthatparametersH,WandSofonedimensionangular-correlationcurvesofthosesamplesvarygreatlywithCr2O3contents.WithCr2O3contentincreasing,HandSparametersincrease,butWdecreases,andreachesextremesatx=0.05;thenwithCr203addingcontinually,parametersHandSdecreasegradually,parameterWincreasesgradually.Thisshowsthat,inaddtiontoCr2O3,theconductivityhascloserelation

简介：PositronannihilationbehaviorshavebeenstudiedinthesinglephaseNd2Fe14BmagnetandthenanocompositeNd2Fe14B/α-Femagnet,preparedbymeltspinning.Theresultsshowedthatthenumberofvacancy-clusteratgrainboundariesincreaseswithincreasingannealingtemperatureforthebothtypesofmagnets.Theincreaseofthiskindofdefectcanimprovethecoercivityof