Minor actinide fission induced by multi-nucleon transfer reactions in

23 Pages·2012·6.53 MB·English

Minoractinidefissioninducedbymulti-nucleontransferreactionsininversekinematics
5thASRCInternationalWorkshop: "PerspectiveinNuclearFission"-JAEA,To¯kai
Minor actinide fission induced by multi-nucleon
transfer reactions in inverse kinematics
XavierDerkx12∗etal.
1GANIL,CEA/DSM-CNRS/IN2P3,Caen,France
2LPCCaen,ENSICAEN,UniversitédeCaen,CNRS/IN2P3,Caen,France
∗Presentaddress:
NuclearPhysicsResearchGroup,UniversityoftheWestofScotland,Paisley,UK
March,the16th2012
XavierDerkx 5thASRCInternationalWorkshop:"PerspectiveinNuclearFission"-JAEA,To¯kai March,the16th2012 1/20
Minoractinidefissioninducedbymulti-nucleontransferreactionsininversekinematics
Outline
1 Somemotivationsfor(still)studyingActinidefission
2 Methods&Technics
Actinideproductionandfission
Usingthekinematics
3 FissionProgrammeatGANIL
Description&set-up
Technicallimitations
Results
4 Improvements(since2010)
Upgradeddetectionsystem: SPIDER1.5
Latestnews: SPIDER2.0
5 Conclusions&Perspectives
XavierDerkx 5thASRCInternationalWorkshop:"PerspectiveinNuclearFission"-JAEA,To¯kai March,the16th2012 2/20
Minoractinidefissioninducedbymulti-nucleontransferreactionsininversekinematics
Motivations
Deeperfissioninvestigationrequiredfor:
Nuclearastrophysics(r-process)
HeavyRIB(e.g.SPIRAL2@GANIL)
FuelcycleforGENIVreactors(Th)
Wasteincinerations(Np,Am,Cm)
Mainobservablesofinterest:
Fissioncrosssections/probabilities
Fissionfragementisotopicyields
Fission,atoolfor:
testingshellmodelsandnucleardynamics
⇒Lowenergyfissionisasymmetricinactinideregion
dataevaluation(IAEA/ENDF,OECD/JEFF,etc.)
⇒Improvingsafetyandallowingdesignstudiesfornewfacilities
XavierDerkx 5thASRCInternationalWorkshop:"PerspectiveinNuclearFission"-JAEA,To¯kai March,the16th2012 3/20
Minoractinidefissioninducedbymulti-nucleontransferreactionsininversekinematics
Neutron irradiation
Historicalmethodtoinducefission(O.Hahn,F.Strassmann&L.Meitner,1939)
Directresultsforapplications(nuclearenergy,militarypurpose,etc.)
Butlimitedtolonghalf-life/lowactivityactindes
Twotechnicallimits:
highenergyneutronbeams→lowintensity
⇒thicktarget⇒highactivity
highfluxreactors→thermalneutronsonly
⇒fissibleisotopesonly(e.g.235Uand239Pu)
⇒Lackofsystematicsintheactinideregion
XavierDerkx 5thASRCInternationalWorkshop:"PerspectiveinNuclearFission"-JAEA,To¯kai March,the16th2012 4/20
Minoractinidefissioninducedbymulti-nucleontransferreactionsininversekinematics
Surrogate method: principle
Aim
Producingactinidesnotaccessiblebyneutron-capturebyalternativereactionstoenlargethe
systematics
Developpedinthe70’sbyCramerandBritt
atLosAlamos
Usualsurrogatereactions:
lighttransfer:(d,pf),(t,pf),(3He,αf)
inelasticscattering:(α,α’f)
gammacapture:(γ,f)
XavierDerkx 5thASRCInternationalWorkshop:"PerspectiveinNuclearFission"-JAEA,To¯kai March,the16th2012 5/20
Minoractinidefissioninducedbymulti-nucleontransferreactionsininversekinematics
Surrogate method: theory
Compoundnucleusapproach
σa→b(E∗)=(cid:80)J,πσaCN(E∗,J,π)×Pb(E∗,J,π)
Pbindependantoftheformationprocess
Surrogatemethodfor(n,f)
Neutron-capturecrosssectionfromopticalmodelcalculations
Fissionprobabilitymeasurementfromanalternativereactionto(n,f)
Obtentionofthe(n,f)crosssection
Validity
(J,π)populationofthecompoundnucleusdependantoftheformationprocess
Weisskopf-EwingapproximationofHauser-Feshbachstatisticalmodel:
ifE∗highenoughtoreachthecontinuumandJCN <J (6-7(cid:126)foractindes)
cut-off
⇒P (E∗,J,π)(cid:39)P (E∗)
fission fission
Limitsoftheapproximationisstillanopenquestion
XavierDerkx 5thASRCInternationalWorkshop:"PerspectiveinNuclearFission"-JAEA,To¯kai March,the16th2012 6/20
Minoractinidefissioninducedbymulti-nucleontransferreactionsininversekinematics
Direct kinematics
Limits
lab∼centreofmass⇒Ωlab =4π
lowEk forfissionfragments
245Am(nth,f)@ILL(Grenoble) 239Pu(nth,f)@ILL(Grenoble)
(Z,A)identificationuptoA<120and (Z,A)identificationforsomeheavyfragments
Z <48(D.Rochman,PhDthesis2001) withγspectroscopy(A.Bail,PhDthesis2009)
XavierDerkx 5thASRCInternationalWorkshop:"PerspectiveinNuclearFission"-JAEA,To¯kai March,the16th2012 7/20
Minoractinidefissioninducedbymulti-nucleontransferreactionsininversekinematics
Inverse kinematics
K.-H.Schmidtetal.,NPA665(2000),221-267-GSI
Advantages
Forwardfocusoffissionfragments
→betterdetectioneffiency
Higherkineticenergyforfissionfragments
→Higherresolutionforidentification,evenfortheheaviestfragments
Higherpuritywithlighttargets
→isotopiccontamination,O,N,Cl,Cbackinginactinidetargets
⇒Isotopicidentificationaccessibleforallthefissionfragments
XavierDerkx 5thASRCInternationalWorkshop:"PerspectiveinNuclearFission"-JAEA,To¯kai March,the16th2012 8/20
Minoractinidefissioninducedbymulti-nucleontransferreactionsininversekinematics
Original experiment (Spring 2008) - F. Farget
What?
Usingmulti-nucleontransfersassurrogatereactionsininversekinematicstostudypoorlyknown
actinidefissionandtheirfissionfragmentdistribution
How?
238Ubeamat6.09AMeVon12C(∼10%abovetheCoulombbarrier)
"Heavy"target:∼10channelsexpectedwithσ >1mb:U,Np,Pu,Am&Cmisotopes
transfer
Neutron-richisotopes((cid:54)=fragmentationatGSIbyK.-H.Schmidtin2000)
Requiredahighintensity238Ubeamandverylargeacceptancespectrometer⇒GANIL
Whatfor?
Explorativeexperimentfor:
Minoractinidesidentification
Fissionfragmentcompleteisotopicproductionrates(cf.nexttalkbyM.Caamaño)
Fissionprobabilitiesmeasurements
XavierDerkx 5thASRCInternationalWorkshop:"PerspectiveinNuclearFission"-JAEA,To¯kai March,the16th2012 9/20
Minoractinidefissioninducedbymulti-nucleontransferreactionsininversekinematics
Set-up
Actinideidentification⇒SPIDER
Fissionfragmentidentification⇒VAMOS
Fissionfragmentspectroscopy⇒EXOGAM
XavierDerkx 5thASRCInternationalWorkshop:"PerspectiveinNuclearFission"-JAEA,To¯kai March,the16th2012 10/20