正电子湮没多参数测量系统研制

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1、中国科学技术大学博士学位论文正电子湮没多参数测量系统研制姓名：孔伟申请学位级别：博士专业：粒子物理与原子核物理指导教师：周先意;叶邦角20040501lFIUr湮没多参数测量系统Ⅲ制中闰科学技术人学悻箪l-学世论之作为研究缺陷类型的例子。第四章主要介纠了寿命-动量关联测姑系统，井详细讨论了计数率对能谱谱形的影响以及对麻的改进上作，测量的实例是碳纳米管材料。互I!￡塑鲨兰茎塑型墅墨竺业型!旦型兰丝查苎兰堡!：兰丝笙墨AbstractThePAS(PositronAnnihilationSpectroscopy)，asaco

2、mmonmethodtostudythestructureofmaterials．hasitsinbornadvantageinthestudyofdefectsinsolids．‘Originally，thePASincludesPAL(positronannihilationlifetimespectroscopy)，DEBS(Dopplerbroadeningenergyspectrum，orDBAR，DopplerBroadeningAnnihilationRadiation)，ACAR(Angularcorre

3、lationofannihilationradiation)．AfterthegreatadvancingofPASin1960s’，researchersdon’tfeelthesetechniquesareenough，andtheybegintofindothermethodstostudythematerialswithpositron．Aftertheireffort，newtechniquesappeared，suchas2D·DBAR(2-DetectorDopplerBroadeningAnnihilat

4、ionRadiation)，AMOC(Age—MomentumCoincide，AMOC)，PAES(PositronAnnihilationinducedAugerElectronSpectroscopy)，etc．Becauseofthedifficultytorealizethesesystems，thereislittleattentiononthesetechniquesintheirfirstyears．In1990’s，aftertheinprovementoftheelectronictechnique，

5、manysystemsarerealized，andplayimportantrolesinstudyofdefectandthestructureofmaterials．Inthesemethods，themulti—parametermeasurementsystem，suchas2D·DBARandAMOC，cangetabundantinformationinmaterials．The2D—DBARisusedinthefieldofelementalspecificityandstudyofthechemica

6、lenvironmentintheannihilationsite，andAMOCcanbeusedtostudytheformationandannihilationofpositronium，thetranslationofdifferentstate．Thesetwomethodscanhelpustodiscovermoredetailsinmaterials．DigitaltechnologyisbeWidelyusedinnuclearphysicsandpaticlephysics．Today,weCall

7、processdigitalpulsedirectlyowetotheimprovementofdigitaltechnology．Thesedigitalmethods，especiallythedCFD，areusedinPALandTOFspectrometersuccessfully．ItwillbenefitPAStousemulti—parametermeasurementanddigitaltechnology．Anew2D·DBARsystemissetupforadvancedstudyindefect

8、sofmaterialsandanoriginalmodelofAMOCissetupdependingontheexperienceofbuilding2D—DBARsystemThedifferencebetweenthesetwosystemsandsomeother2D·DBARandAMOCsystemsi