Precise measurement of cross section of 3He(3He,2p)4He by using He-3 doubly charged beam23-第4页
上亿文档资料，等你来发现
Precise measurement of cross section of 3He(3He,2p)4He by using He-3 doubly charged beam23-4
plotisdividedinto16000pa；Experimentalresultsareas；η(x)=16000??i=xNa(i),(7)；wherei=xto16000,Na(i)ist；A(x)=16000??i=x{Nd(i)?Nb；where,A(x)referstoaccept；3He(3He,2p)4Hereactionca；V.EXP
plotisdividedinto16000partsof100keV×100keVpartsasshowninFig.17.ThesignaltonoiseratiowhichshouldbederivedfromtheMonteCarloMC(3He+3He)dividedbyMC(3He+D)andmeasuredbackgroundwasallottedfor16000parts.AllpartsareorderedasafunctionoftheirS/N;partshavingabetterS/Narelocatedattherighthandsidewhileworsepartsarelocatedtotheleft,asshowninFig.18.Fig18(a)showsthedistributionofthesimulatedeventsfromthe3He+3HereactionasafunctionofS/Nratio.Manyeventsarelocatedintherighthandsideinthe?gure,thatshouldcorrespondtothebetterS/N.Also,Figs.18(b)and(c)showthedistributionofthesimulatedeventsfor3He+dreactioneventsandtheobservedbackgroundeventsasdiscussedabove.Itisusualthatthesebackgroundeventsshouldbelocatedinthelefthandsideofeach?gure.Fig.18(d)showsthedistributionoftheobservedeventfor3He+3HereactionatEcm=45keV,asafunctionofS/N.Thecontributionfromthebackgroundeventsisapparentlyverysmall.ThereforetheobserveddistributionasshowninFig.18(d)isparticularlysimilartothesimulatedone,shownninFig.18(a),withoutsubtractionofanybackgroundeventsasshowninFig.18(d).Since,mostofthebackgroundeventsexistinchannelslessthan13000(Fig.18)theacceptableareaforthe3He+3Hereactioncouldbeassignedtochannelslargerthan13000channel.TheregionofthatisshowninFig.19.Experimenta3344countsareobservedintheacceptableregion,whilethecontributionfromthe3He+Deventstotheregionis20.9counts,andthatfromtheotherbackgroundcomponentis2.46counts.Aftersubtractingthenumberofthesebackgroundeventsfromthenumberofobservedeventsintheacceptableregion,thenumberoftrueeventsforthe3He+3Hereactionis3337.4,withastatisticalerrorof1.8%.Accordingtothisprocedure,thedetectionef?ciencyη(x)canbewrittenasη(x)=16000??i=xNa(i),(7)wherei=xto16000,Na(i)isthenumberofcountsforthesimulateddistribution,andxistheparameteroftheboundarycutpointfortheacceptedevents.TheacceptedeventhavebeenderivedasA(x)=16000??i=x{Nd(i)?Nb(i)?Nc(i)},(8)where,A(x)referstoacceptedeventsforthe3He(3He,2p)4Hereaction,Nd(i),Nb(i),Nc(i)arethenumberofcountsfortheobservedevents,forthed(3He,p)4Heandforotherbackgroundevents,respectively.FinallytheratioofA(x)/y(x)correspondingtothecrosssectionofthe3He(3He,2p)4Hereactioncanbeobtained.TheratioslightlydependsontheboundaryparameterxasshowninFig.20.Thus,theaccuracyofthesimulatedenergydistributioninascatterplotshouldbederivedfromthe?uctuationofthisratio.Whenweincludethegeometricaluncertaintyofthecountertelescope,i.e.,0.5%uncertaintyofthedetectionef?ciencysimulatedwithMonteCarloprogram,thesystematicalerrorofthedetectionef?ciencyisevaluatedtobe3%.V.EXPERIMENTALRESULTSANDDISCUSSIONTheexperimentalresultsforthecrosssectionandS-factorsobtainedforthe?rstseriesofOCEANexperimentsasfromtheyear2000,togetherwiththeexperimentalconditionssuchasthelivetime,beamcurrent,thetargetgaspressure,andthetargettemperatureareshownintableIII.Theobservedeventsforthe3He(3He,2p)4HereactionandthebackgroundeventsfromvarioussourcesarealsoshowninthesametableIII.Thecrosssectionforthe3He(3He,2p)4Hereactionhasbeenderivedfromthefollowingequa-tion,N=Nt?Nb?σ(Ee?)???η(E)??(E)?1?dE.(9)whereNisthenumberofcountsfor3He(3He,2p)Hereaction,Ntisthe3Hetargetdensity,Nbisthe3Hebeamintensity,Ee?istheeffectivereactionenergy,η(E)istheabsolutedetectionef?ciency,and?(E)isthestoppingpower.TheastrophysicalS-factorswerededucedfromtheequationσ(E)=S(E)L4E)1/2(11)whereZ1andZ2arethenuclearchargesoftheinteractingparticlesintheentrancechannel,μisreducedmass(inunitsofamu)andEisthecenterofmassenergy(inunitsofkeV).OurpresentdatabetweenEcm=45keVto31keVofS(E)areingoodagreementwiththeresultsofexistingdataofKraussetal[2].Theaccuracyofbothstatisticalandthesystematicaldataofthepresentmeasurementisbetterthanthatinref.[2].Forthelasttwodecades,studiesofthe3He(3He,2p)4Hereactionhavebeencarriedoutoverawiderangeofenergies(BacherandTombrello[13],DwarakanathandWinkler[14],Kraussetal[2],andLUNA[1]).Ofthepreviousstudies,experimentsbetween17.9to342.5keVcenterofmassenergybyKraussetalcoverawiderenergyrangethanotherssincetheyusedtwoaccel-eratorsof350kVacceleratorinMunsterUniversityand100kVfacilityatBochumUniversity.RecentlytheLUNAgroupintheLNGShaspresenteddatadownto16.50keVcenterofmassenergy,althoughthedatawasobtainedwithtwoseparateexperimentalset-ups,namelyatthe450kVacceleratoratBochumandalso50kVatLNGS.Thereremainsunaccesibleregionofenergybetween45.82keVand24.80keV.ThedatainthisenergyregionhasbeensuppliedbyKraussetal.Inthesepreviousexperimentsthereweremanyeffortstoobtainthetruescarceeventsfromthecontaminatedbackgroundevents,suchasdeuteriumcontaminationbothintheincidentbeamandinthetargetgas,cosmicrays(mainlymuon)orheavyparticles,andelectricnoise.Therehavebeenseveralsolutionsforthesedif?Kraussetal.,pointedoutin1987thepurityoftheionbeamandofthetargetwereofspecialinterestandtheyestimatedthatat350keVthemass-3beamcontaminationHD+wasoftheorderof10?5[2].Alsotheyappliedproton-protoncoincidencestodiscriminatetherealeventsfromintrudedeventsfortheD(3He,p)4Hereaction.TheysurroundedthetargetchamberwithNE102Aplasticscintillatorinordertoidentifyforcosmicevents.Inthiswaytheunidenti?edcosmicbackgroundcoincidenceeventratewasestimatedtobelessthan1event/200hinthemeasurementsatEcm&50keV.Anothersourceofbackgroundeventsduetooccasionaldischargesoftheacceleratorhighvoltagecouldbeavoidedbyampli?er?lterornoise?lter.Inspiteoftheseefforts,theystillconsiderthecontributionoftheeventscausedbythehighenergyprotonsfromthe3He(d,p)4Hereaction(e.g.2.5%contributionatEcm=25keV).Theyalsoevaluatedthatthebackgroundcontributiontothe3He+3Heregionis0.40%oftheobservedcountsofthed-3Heevents.ThemeasurementsattheDTLshowedthatcosmicraysproducedeventswithinthedE-Eregionofthe3He(3He,2p)4Hereactionamountsto3.5×10?4events/s,whileinthelatterplaceatLNGSthisratewasobservedtobereducedbyatleastafactor200,thatis,1.8×10?6.Itwillbenegligiblysmallforthelowenergymeasurementlessthan30keVcenterofmassenergy.WenowarguethattheOCEANfacilitycouldovercomethesedif?cultiesbyapplyingthefol-lowing,whiletherestillexistthepossibilitiesofbackgroundduetothetargetgas:1)OnlyOCEANexploitsdoublychargedHe-3ionsproducedwithanECRionsourceanditcouldavoidthebackgroundeventsduetoD(beam)+3He.Kraussetalperformedap-pcoinci-denceexperimenttodiscriminatethetrueevent,butitcouldnotbeappliedforthecenterofmassenergylessthan25keV.2)OurfacilityOCEANhasbeenlocatedinanexperimentalareaofthecyclotronandshieldedwith5mofthickconcrete.Wehaveobservedthebackgroundeventsarisingfromcosmicraysin38daysandalsoobservedtheeffectfromtheinducedeventsduetothehighenergyparticlesbyusingVeto-counterscomposedofplasticscintillatorslocatedupanddownthetargetchamber.BythisconditionoftheOCEANsightwestillhaveasuf?cientsignaltonoiseratioof10timeslargerthanunknownfakeeventsaslistedintableIII.Generally,therearestillmanydiscussionsforthescreeningpotentialwhichenhancethecrosssectionremarkablyforlowenergyfusionreactions.Arecentresultofthe3He(3He,2p)4HereactiondataassumedforelectronscreeningwithUe=330eVandadoptedapolynomialfunctionforS(E)factor,namelyS(E)=5.18+2.22E+0.804E2.TheS(0)valueisclosetotherecommendedvalueofAD98(5.4+0.4MeVb).Inareviewarticleconcerningsynthesisoftheelementsinstars[15],itcitedLUNAdataasS(E0)=5.3±0.05(stat.)±0.30(syst.)+0.30(Ue)MeVb.ItstillincludesaUevaluewhichsuggeststhattheeffectivevalueofUemaybelargerthantheadiabaticlimit.Furthermore,itismentionedthatimproveddatashouldbeobtainedatenergiesfromE=25keVto60keVtocon?rmorrejectthepossibilityofarelativelylargersystematicerrorintheS(E)dataaroundtheseenergies.VI.CONCLUSIONANDPERSPECTIVESThepresentexperimentwithOCEANhasprovedtoreinforcethecompilationdatafornuclearastrophysicsinsolarfusionrates.Highcurrentandlowbackgroundsystemcouldmeasurethecrosssectioninthecenterofmassenergyrangefrom50to30keV.Asasecondseriesofexperi-ments,wehavestartedtomeasureatenergieslessthan30keV,andtheseresultswillbereportedinthenearfuture.Betterresultswithrespecttoreducedstematicandstatisticalerrorscomparedtoexistingdataareexpected.Whenweapplyabeamintensityof1mAforthe3He2+beamatEcm=20to30keVandatargetgaspressureof0.1Torr,wecanexpect70～2eventsperdayforrealevents,whilethefakeeventwillbe6～1.8eventsperday.Hence,weexpectameasurementwithastatisticalerrorofabout10%inthisenergyrange.AcknowledgmentsTheauthorsgratefullyacknowledgeProfessorClausRolfsforthedesignoftheOCEANaccel-eratorfacility.WeacknowledgeProfessorT.HasegawaforintroducingECRionsourceasabright3Heparticlesource.WethankDr.UweGreifeandDr.MathiasJunkerformanysuggestionstomeasurethereactioncrosssectionofrareeventsfromtheirexperience.WethankProf.H.Ejiri,Prof.Y.NagaiandProf.H.Tokiforvarioussuggestionsanddiscussions.WealsothankProf.G.Hillhouseforreadingcriticalmanuscript.ThisworkwassupportedbytheGrant-in-AidofScienti?cResearch,MinistryofEducation,Science,CultureandSports,No.,andNo.0041120.[1]U.Grief,C.Ascella,C.A.Barnes,F.Bartok’s,E.Ballot,C.Bragging,P.Crosier,et.al,,Nucl.Instr.andMeth.inPhys.ResearchA350,327(1994);U.Griefe,F.Gorris,M.Junker,C.Rolfs,D.Zahnow,Z.Phys.A351,107((1995);M.Junker,A.D’Alessandro,S.Zavaterelli,etal.,Phys.Rev.C57,);R.Bonetti,C.Broggini,L.Campajola,P.Corvisiero,A.D’Alessandroetal,Phys.Rev.Lett.82,);H.Constantini,A.Formicola,M.Junker,R.Bonetti,C.Broggini,etal.,Phys.Lett.B482,43(2000).[2]A.Krauss,H.W.Becker,H.P.TrautvetterandC.Rolfs,Nucl.Phys.A467,273(1987).[3]P.Sortais,C.Bieth,P.Foury,N.Lecesne,R.Leroy,J.Mandin,C.Marry,J.Y.Pacquet,E.RobertandA.C.C.Villari,Proc.ofthe12thIntern.WorkshoponECRionsources,RIKEN,Japan(1995)pp.45;R.Leroy,J.C.Angelique,P.Bertand,G.B.Blank,M.Ducourtieux,P.Foury,N.Lecesne,A.Lepine,M.Lewitowicz,C.F.Liang,J.Mandin,C.Marry,L.Maunoury,J.Mercier,J.Obert,N.A.Orr,J.Y.Pacquet,P.Paris,J.C.Potier,J.C.Putaux,E.Robert,M.G.Saint-Laurent,P.SortaisandA.C.C.Villari,Proc.ofthe12thIntern.WorkshoponECRionsources,RIKEN,Japan(1995)pp.57.[4]T.Itahashi,K.Takahisa,N.Kudomi,etal.,Rev.ofScienti?cInstruments69,);TItahashi,N.Kudomi,K.Kumeetal.,Rev.ofScienti?cInstruments71,).[5]A.Wollnik,WINGIOS(IONTECH),version2.0[6]K.Langanke,etal.,Phys.Lett.B369,211(1996).[7]C.H.ThomannandJ.E.Benn,Nucl.Instr.andMeth.293,138(1976);A.E.Vlieks,M.HilgemeierandC.Rolfs,A.E.Vlieks,etal.,Nucl.Instr.andMeth.213,291(1983);J.M.Nitschke,Nucl.Instr.包含各类专业文献、文学作品欣赏、行业资料、生活休闲娱乐、专业论文、中学教育、应用写作文书、高等教育、外语学习资料、Precise measurement of cross section of 3He(3He,2p)4He by using He-3 doubly charged beam23等内容。 Financial Intermediaries and the Cross-Section of Asset ：金融资产的横..
扫扫二维码，随身浏览文档
手机或平板扫扫即可继续访问
Financial Intermediaries and the Cross-Section of Asset ：金融资产的横截面
举报该文档为侵权文档。
举报该文档含有违规或不良信息。
反馈该文档无法正常浏览。
举报该文档为重复文档。
推荐理由：
将文档分享至：
分享完整地址
文档地址：
粘贴到BBS或博客
flash地址：
支持嵌入FLASH地址的网站使用
html代码：
&embed src='/DocinViewer-4.swf' width='100%' height='600' type=application/x-shockwave-flash ALLOWFULLSCREEN='true' ALLOWSCRIPTACCESS='always'&&/embed&
450px*300px480px*400px650px*490px
支持嵌入HTML代码的网站使用
您的内容已经提交成功
您所提交的内容需要审核后才能发布，请您等待！
3秒自动关闭窗口cross-section of conductor的意思
沪江词库精选cross-section of conductor是什么意思、中英文句子翻译、英语短语。
cross-section of conductor是什么意思： 导线截面
This shows that the resistance of an electric
conductor is inversely proportional to its cross-sectional area.
这表明，导体电阻的大小与导体横截面的大小成反比。
英语短语推荐
2015cross-section of conductor是什么意思由沪江网提供。This paper studies cross-sectional variations in trading activity for a..
扫扫二维码，随身浏览文档
手机或平板扫扫即可继续访问
The Cross-Section of Expected Trading Activity
举报该文档为侵权文档。
举报该文档含有违规或不良信息。
反馈该文档无法正常浏览。
举报该文档为重复文档。
推荐理由：
将文档分享至：
分享完整地址
文档地址：
粘贴到BBS或博客
flash地址：
支持嵌入FLASH地址的网站使用
html代码：
&embed src='/DocinViewer-.swf' width='100%' height='600' type=application/x-shockwave-flash ALLOWFULLSCREEN='true' ALLOWSCRIPTACCESS='always'&&/embed&
450px*300px480px*400px650px*490px
支持嵌入HTML代码的网站使用
您的内容已经提交成功
您所提交的内容需要审核后才能发布，请您等待！
3秒自动关闭窗口Absorption Cross Section of Smeared D3-Brane on a Circle_百度文库
两大类热门资源免费畅读
续费一年阅读会员，立省24元！
评价文档：
38页免费94页免费57页免费42页免费29页免费20页免费18页免费13页免费12页免费11页免费
Absorption Cross Section of Smeared D3-Brane on a Circle|T​h​e​ ​e​v​a​l​u​a​t​i​o​n​ ​o​f​ ​t​h​e​ ​a​b​s​o​r​p​t​i​o​n​ ​c​r​o​s​s​ ​s​e​c​t​i​o​n​ ​o​f​ ​a​ ​m​a​s​s​l​e​s​s​ ​s​c​a​l​a​r​ ​f​i​e​l​d​ ​p​r​o​p​a​g​a​t​i​n​g​ ​o​n​ ​a​ ​n​o​n​-​e​x​t​r​e​m​a​l​ ​b​l​a​c​k​ ​D-​b​r​a​n​e​ ​s​m​e​a​r​e​d​ ​o​n​ ​a​ ​c​i​r​c​l​e​ ​i​s​ ​c​o​n​s​i​d​e​r​e​d​.​ ​T​h​e​ ​s​o​l​u​t​i​o​n​ ​t​o​ ​t​h​e​ ​s​c​a​l​a​r​ ​f​i​e​l​d​ ​e​q​u​a​t​i​o​n​ ​o​f​ ​m​o​t​i​o​n​ ​a​t​ ​h​i​g​h​ ​t​e​m​p​e​r​a​t​u​r​e​ ​i​s​ ​o​b​t​a​i​n​e​d​ ​i​n​ ​t​e​r​m​s​ ​o​f​ ​t​h​e​ ​p​a
把文档贴到Blog、BBS或个人站等：
普通尺寸(450*500pix)
较大尺寸(630*500pix)
你可能喜欢
