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382Vol.38,No.220043AtomicEnergyScienceandTechnologyMar.2004(,102413):,DTL100kVD(d,p)T,,,,:;S(E);:O57114:A:100026931(2004)0220097208ElectronScreeningEffectsinFusionReactionsatLowEnergiesLIANGang(ChinaInstituteofAtomicEnergy,P.O.Box275246,Beijing102413,China)Abstract:Theexperimentalandtheoreticalstudiesoftheelectronscreeningeffectsincharged2particleinducedreactionsatenergiesofastrophysicalinterestaresummarizedbriefly.Foradeepunderstandingofelectronscreeningeffects,theD(d,p)Treactionhasbeenstudiedinaseriesofdeuteratedmetal2,insulator2andsemiconductortargetsusingthe100kVacceleratoroftheDynamitron2Tandem2LaboratoriumattheRuhr2University2Bochum.AscomparedtomeasurementsperformedwithagaseousD2target,alargeeffecthasbeenobservedinmostmetals,whileacomparativelysmalleffectisfoundintheinsula2torsandsemiconductors.AreasonableexplanationofthelargeeffectinmetalsispossiblyprovidedbytheclassicalplasmascreeningofDebyeappliedtothequasi2freemetallicelec2trons.Thesubsequentexperimentsarealreadyinprogresstoprovethisexplanation.Theda2taalsoprovidedsomeinformationonthesolubilityofhydrogeninthesamples.Keywords:electronscreeningeffects;astrophysicalS(E)factor;Debyemodel:2003207214;:2003210210:(19935030);(G2000077400);(10025524):(1975),,,,©1994-2006ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.[1],[24],[57],,,,,(pycnonuclearreaction),;,,,1111,(E),,(E)S(E),:(E)=S(E)E-1exp(-2)(1):,2=2Z1Z2e2/Ü=31.29Z1Z2(/E)1/2,Z1Z2,E()(keV);S(E),;E-1;Gamowexp(-2),,(),,1[5]1()Fig.1EffectoftheelectroncloudoftargetnucleusuponCoulombpotentialbetweenthetargetnucleusandprojectileRnRaRc;Ec,,s(E)b(E)EEeff=E+Ue,Gamow,Ss(E)[8]:flab(E)=s(E)/b(E)=Ss(E)/Sb(E)8938©1994-2006ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.(E+Ue)exp(Ue/E)(2):Ue;Ss(E)Sb(E)S(E)(2),112(2):1),Sb(E);2)Sb(E);3)Ue,Sb(E)(2)Ss(E)2Fig.2Approachformeasuringelectronscreeningeffect113,Ra,,Z1e/Ra,,Ue=Z1Z2e2/R[6]R,[8],,,,,,,1,,1UeTable1ComparisonsbetweentheoreticandexperimentalUevaluesforsomelightnucleusfusionreactionsUe/eVD(d,p)T14255Greifeetal.[9]3He(d,p)4He12018612Pratietal.[10]D(3He,p)4He651239Pratietal.[10]7Li(p,)4He182300280Engstleretal.[11]11B(p,)8Be+34843080Anguloetal.[12]2D(d,p)TAlZrTaD(d,p)T,[13],(19015)(2978)(32215)eV,,100kVTaD(d,p)T,[14],[15]2113100kVD+1D3+,Ed=4100keV,15mm,41cm5cm1304600mm2992:©1994-2006ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.,pT0175mNi,Tp4T,,,D(d,p)T[9],3Fig.3Schematicdiagramoftheexperimentalsetup4TaD(d,p)TFig.4EnergyspectrumoftheD(d,p)TreactionindeuteratedTatargetatEd=48keV2121)D(d,p)T()(5)5,1C,,5TaD(d,t)TFig.5ProtonyieldofD(d,p)TasfunctionofdeuteronimplantationchargeinTafoil,(ERDA):,MxDM,x,M2)D(d,p)TD+31290keV(Ed=430keV)(3090keV)3keV,(1230keV)115keV66TaD(d,p)TFig.6EnergydependenceoftheyieldfromD(d,p)TreactioninthickdeuteratedTatarget2131)00138©1994-2006ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.:Yrel(Ed,)=Np/N(3):Np;N4K(Ed,)D(d,p)TW(Ed,)[9],,:Y(Ed,)=R0K(Ed,)W(Ed,)(Ed)dx=0EdK(Ed,)W(Ed,)(Ed)dxdEdE=Ed0K(Ed,)W(Ed,)(Ed)eff(Ed)-1dE(4):R;eff(Ed)2),K(Ed,)W(Ed,)eff(Ed)-1,Ed2eff[5](Ed2eff),,Ed2eff:Y(Ed2eff,)=-1EE-K(Ed,)W(Ed,)eff(Ed)-1(Ed)dE=eff(Ed2eff)-1(Ed2eff)(5):=K(Ed,)W(Ed,)eff(Ed)-1,:Y(Ed2eff,)=(Y(Ed,)-Y(Ed-Ed,))/Ed(6)(6),(5)S3)UeSs(Ed)Sb(Ed),(2),Ue214TaD(d,p)T,S,Sb(E)=Sb(0)+mE,UeSb(0)m2(7)Ue=(30912)eV,Sb(0)=(431)keV,m=(0.540.05)b(1b=10-28m2)7TaD(d,p)TS(E)Fig.722fitofastrophysicalS(E)factorofD(d,p)TreactionwithadeuteratedTafoilforatomic(D+1)andmolecular(D+3)deuteronbeamsD+3;D+1,40(),Sb(0)m7,Ue2(8):,,343D(d,p)T,,1012:©1994-2006ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.,2Table2Summaryofresults1)ZUe3)/eVxneff3)neff(Hall)4)Be2,6)41804012.30.180.080.210.04Mg2,6)12440408.73.00.51.80.4Al2,6)13520503.83.00.63.10.6V233503016.01.00.21.10.2Cr24220207.80.350.070.200.04Mn25350403.70.900.190.810.16Fe2,6)264606016.01.70.43.00.6Co2,6)27640606.91.20.30.520.10Ni284508026.01.30.31.10.2Cu294705011.11.80.41.50.3Zn2,6)30480507.72.40.52.90.6Nb41400408.71.70.41.20.2Mo42220207.00.460.090.770.16Ru2)44220305.60.440.120.390.08Rn2,6)452304011.00.490.171.70.4Pd6)468009035.05.31.21.20.2Ag47330407.11.30.31.20.3Cd2)48390606.22.20.72.20.4Sn502002036.00.680.15865)Ta73340149.11.30.11.10.2W74220203.30.470.090.840.17Re2,6)75420457.11.70.40.290.06Ir2,6)77200404.40.380.192.80.6Pt784405014.01.80.53.90.8Au79280505.60.90.31.50.3Tl2,6)815509070.05.81.27.41.5Pb824405018.03.60.9215)BeO2)304B5302.6Al2O3303.7C2)652203.1Si2)1445204.3Ge2)3260201.8Sc21300.7Ti22300.75Y39700.56Zr4083200.42Hf7287200.55Eu63501.7Dy66300.9Er68501Yb70400.77:1)t=-102)t=203)4)t=20,20%5),6)35keVKr20138©1994-2006ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.,,[15],[14],,[14],:Bragg,;S,,:RDebye=0kTnae21/2(8):0;n;a:Ue=Z1Z2e240RDebye(9)T=293Kneff=1a=61022cm-3(8)(9),(Ue=300eV)(neff),Ueneff,(2),,(8)(9),,:[1]1[J]1,2002,19(1):7121[2]KraussA,BeckerH