用羊八井宇宙线观测实验寻找甚高能γ暴

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1、话南交通必学硕士研究熊掌位谂文黧11I孤AbstractGamma-RayBursts(G黼s)havebeenstudiedbyspaceexperimentsandground-basedexperirne囊tssincetheirdiscoveryin{9皤了．U嫩鲑now,Wehavegotrichinfonnationsonthepropeties(timeprofile、energyspectrumandspatialdistribution)of潲s,b激㈣s嚣绻stillthemostmysteriousastronomicalphenomenon溉origino

2、fGRBsremainsunclear,eventhedistanceiSunsolved．Uptonov,．aboutthreethousandsofGR嚣shavebeenobservedbysatelliteexperimentsandsomeofthemhavebeenobservedafterglows．TheresultsconfirmedthatthespatialdistributionofGRBsishighlyisotropyicalandthecosmologicalmodelWaScommonlyconsidered。裂艟energyofthe好RBsob

3、servedalla描lessthan30GeVforthesmalleffectiveareaofsatelliteexperiments，SearchingforV娃E任》100GeV)GRBsiSveryimportantandhelpdeterminewhetherornottheGRBsai"edistributedcosmologically．Becausethesegammaraysarestronglyattenuatedbyinfraredbaekgroundphotonsand2+7Kmierowavebackgroundradiationphotonsdur

4、ingtheirtraveltowardstheearth．isV}差鏊GRBsexist?Manytheoreticalmodelspredictor毒主leastallowVHEgamma-raysemissionintll2processofGitBs；InGeVenergyregion羞GRETexperimentonCGltohaddetected基怨谨GRBswhichcoincidentwiththeBATSEbursts；TheresultsofBATSEburstsshowmanyburstshaveveryhardspectraandthereisllOcut

5、exist蘸巍ighenergy．Soitispossibleto毽辩ground．basedex'perlmentwithlargeareaandhi曲triggerratetosearchtbrVHEGRBs。Manyground-basedexperimemswerestudyingonTeVGRBs,such鑫sMilagro．HEGRA。TibetASyarray．ButnopositiveVHEGRBsareobservedbynow．Ccmparewith曩袷鞠撼尊甄

6、遗ofotherinsmmaentintheworld,theTibetcosmicmyobser

7、vationexperiment(10catedatYangbajinginTibet,4，310ma，s、1．)hasthelowestthresholdenergyandthehighesttriggerrate。Especial跨fortheTibetlliA寒￥arraywiththethresholdenergyabout1．5TeVandtriggerrateabout680Hz,ithasmanyadvantagesinsearchingfor戮G瑟S。Searchingfor再WGRBsWasmadebyusingtheASn／(TibetIII)data．whi

8、chweretakenfromNov．t999toJuly2002．Inthisanalysis，twomethodshavebeenapplied．FirstissearchingforTeVGRB’ssignalsindependentlyandgotthelowest西南交通大学硕士研究生学位论文第1V页chanceprobability(whichisduetothefluctuationofbackground)about7．2x10”‘：SecondiSsearchi