简介:基于粒子输运蒙特卡罗模拟程序PHEN,建立了一种用于模拟γ射线入射闪烁晶体全响应过程的耦合输运计算方法。利用此方法对γ射线入射锗酸铋(BGO)晶体的响应过程进行了模拟计算,得到了能量为0.5-10.0MeV的γ射线在BGO晶体上的沉积能量、BGO晶体的相对灵敏度以及1MeVγ射线产生的可见光光子数分布,并将计算结果与用MCNP程序计算的结果及BGO晶体的发射光谱进行了对比分析。结果表明,用两种程序计算的沉积能量的差异小于1%,PHEN程序中经过耦合输运得到的可见光光子数分布与BGO晶体的相对发光特性符合较好,验证了本文方法的合理性和可靠性,为闪烁体探测器参数设计及优化提供了一种有效的数值模拟方法。
简介:Wehavedevelopedanewradiographysetupwithashort-pulselaser-drivenx-raysource.Usingaradiographyaxisperpendiculartobothlong-andshort-pulselasersallowedoptimizingtheincidentangleoftheshort-pulselaseronthex-raysourcetarget.Thesetuphasbeentestedwithvariousx-raysourcetargetmaterialsanddifferentlaserwavelengths.Signaltonoiseratiosarepresentedaswellasachievedspatialresolutions.ThehighqualityofourtechniqueisillustratedonaplasmaflowradiographobtainedduringalaboratoryastrophysicsexperimentonPOLARs.
简介:Itisimpossibletodirectlyanalyzethemicrostructureofspin-valvemultilayersbasedonNi,F,CuandMnbyaconventionalX-raydiffractiontechniquebecausethelatticeparameterandatomicsatteringfactorsofthemareveryclose.Tosolvethisproblem,weuseanx-rayanomalousdiffractiontechniquetocharacterizethemicrostructuresofthe[Ni80Fe20/Fe50Mn50]15and[Ni80Fe20/Cu]15superlatticesystems.Theresultsshowthatmorediffractionpeaksandhigherinternsityinthereflectivetyprofileareobservedwhentheincidentenergyisclosetotheabsorptionedgeofthelighterelement(Mn)in[Ni80Fe20/Fe50Mn50]15multilayersystemsandtotheabsorptionedgeoftheheavierelement(Cu)inthe[Ni80Fe20/Cu]15multilayersystems.Theinterfaceandperiodicstructureof[Ni80F20/Fe50Mn50]15aremoreperfectthanthatofthe[Ni80Fe20/Cu]15superlattices.Theaboveresultsaredisussedinthispaper.
简介:Small-angleX-rayscattering(SAXS)usingsynchrotronradiationasX-raysourcehasbeenemployedtocharactcizcthemicroscopicstructrureoforgano-modifiedmesoporousmolecularsieves(organo-MSU-X)preparedbyaone-pottemplate-directedsynthesis.ItisshownthattheSAXSprofileishardlyconstantwithPorod’slawshowinganegativeslope,i.e.,negativedeviation.Thissuggeststhatthereisdiffuseinterfaciallayerlocatedbetweentheporesandthematrix.Thissuggeststhattheorganicgroupsremaincovalentlylinkedtothematrix,asindicatedby^29SiCPMASNMRandFT-IR.Theaveragethicknessoftheinterfaciallayerwasfoundtobeabout1nmforeachofthethreesampleswithdifferentkindsandthesameamounts(20?oforganicgroups.Thiskindofmaterialhasalsobeenprovedtopossessbothsurfaceandmassfractalstructureoftheamophousporoussilicamaterials.2001ElsevierScienceB.V.Allrightsreserved.
简介:ThispaperprovidesareviewonsampleinjectorswhichareprovidedatSPring-8AngstromCompactfreeelectronLAser(SACLA)forconductingserialmeasurementina‘diffract-before-destroy'schemeusinganx-rayfreeelectronlaser(XFEL).VersatileexperimentalplatformsatSACLAareabletoacceptvarioustypesofinjectors,amongwhichliquidjet,dropletandviscouscarrierinjectorsarefrequentlyutilized.Theseinjectorsproducedifferentformsoffluidtargetssuchasaliquidfilamentwithadiameterintheorderofmicrometer,micro-dropletsynchronizedtoXFELpulses,andslowlyflowingcolumnofhighlyviscousfluidwitharatebelow1μLmin-1.Characteristicsandapplicationsoftheinjectorsaredescribed.
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简介:最近,Brutman和Passow认为Newman类型合理插值是to|x|由对称的节点的任意的集合导致了在[-1,1]并且给了近似错误的一般评价。由他们的方法,一个人能为一些特殊节点建立近似的准确顺序。在我们考虑插值节点是第二种类型的零个Chebyshev多项式并且在这种情况中证明那的特殊情况的现在的纸,近似的准确顺序是O(1/(nlnn))。
简介:Amorerelaxedsufficientconditionfortheconvergenceoffiltered-XLMS(FXLMS)algorithmispresented.Itispointedoutthatifsomepositiverealconditionforsecondarypathtransferfunctionanditsestimatesissatisfiedwithinallthefrequencybands,FXLMSalgorithmconvergeswhateverthereferencesignalislike.Butiftheabovepositiverealconditionissatisfiedonlywithinsomefrequencybands,theconvergenceofFXLMSalgorithmisdependentonthedistributionofpowerspectraldensityofthereferencesignal,andtheconvergencestepsizeisdeterminedbythedistributionofsomespecificcorrelationmatrixeigenvalues.ApplyingtheconclusionabovetotheDelayedLMS(DLMS)algorithm,itisshownthatDLMSalgorithmwithsomeerroroftimedelayestimationconvergesincertaindiscretefrequencybands,andthewidthofwhicharedeterminedonlybythe"time-delayestimationerrorfrequency"whichisequaltoonefourthoftheinverseofestimatederrorofthetimedelay.
简介:ThefabricationofX-raymasksisacriticalandchallengingprocessinLIGAtechnique.Asinductivelycoupledplasma(ICP)deepetchingappearstobethemostsuitablesourcefordeepsiliconetching,wefabricatedanewtypeX-raymaskusingthistechnique.IncomparisonwithothertypesofX-raymasks,themaskwefabricatedhastheadvantagesofitslowcostanditssimplefabricationprocess.BesiredmicrostructureshavealsobeenfabricatedusingthisnewtypeX-raymaskinLIGAtechnique.