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LEgnaro NeutrOn Source P.F.Mas(nu1,J.Praena1,3,G.Mar2nHernández2
1LaboratoriNazionalidiLegnaro,INFN,Italia.2CEADEN,LaHabana,Cuba.
3UniversidaddeSevilla,CNA,Spain.
WhatwouldbeLenos?
• FacilityforNeutronAc(va(on(NA)• PossiblefutureupgradewithaTOFline.• MeasurementsofshortmeanlifeisotopestargetsimplantedwithSPESTheIdea:shapetheprotonbeamtoshapethe
neutronbeamtoadesireddistribu(on
• NuclearAstrophysics.• Valida(onofEvaluatedDataforenergyandnon‐energyapplica(ons
Lenos collaboration is completly open to new applications and collaborations
Mo(va(ons
Mo(va(ons:Astrophysics(1/3)
Nucleosynthesis of elements beyond Fe (B=8.8 MeV/A) are produced in stars (mainly AGB and Massive star) by (n,γ). Stellar neutron distribution is Maxwell Boltzmann. Depending on the stellar site and shell the most important kT are 8, 30 or 90keV.
MACS (Maxwellian Averaged Cross Section)
r‐process• Short(mescale.• Highneutronflux:1020cm‐3.• relatedtoexplosivescenarios.Wai(ngpoint
Mo(va(ons:Astrophysics(2/3)
s‐process
Branchingpointsareunstable(SPESRIB)andcanbeusedtodeterminetheenviromentalquan(ty(density,neutronfluxandtemperature).
THE PROBLEM • The uncertainties in the MACS of several
stable and most of the unstable elements are higher than the requested accuracy.
• Required uncertainties for s-process: 3-5%
Mo(va(ons:Astrophysics(3/3)
Main library
for MACS
Most of the MACS at kT=30keV were not measured directly. It has been extrapolated from 25kT=keV
First application of Lenos could be the measurement of the most important isotopes at kT=30 keV.
Long list of branching points for which the MACS has not jet been measured: 63Ni, 79Se, 85Kr, 95Zr, 147Nd, 147,148Pm, 154,155Eu, 153Gd, 160Tb, 163Ho, 170,171Tm, 179Ta, 185W, 204Tl…
Some actinides for AFC and Gen-IV: Pu-239 fission in 1 keV – 1 MeV Pu-241 fission in 1 keV – 1 MeV U-238 capture in 2 – 200 keV Am-243 capture in fast and thermal energy range Am-241fission in fast energy range
P. Oblozinsky, NNDC
Mo(va(ons:Valida(onofEvaluated
NuclearData
Often large discrepances between data bases (ENDF,JENDL,JEFF,BRONDL) for many already mesured isotopes. No mesurements for some important isotopes (mainly radioactive)
Mo(va(ons:Valida(onofEvaluated
NuclearData
• Awellcaractherizedneutronspectrumitisneededforvalida(onofEvaluatedData(integralmeasurements),mainlyonepithermalrange.
• Asitwillbeshowninthispresenta(onshouldbepossibletohaveaquasiperfectneutronmaxwellianspectrum.AtleastatkT=30keV.
• Withthesametechniquea
1/Ebehaviourshouldbepossible
SPES @ LNL
• RFQ:
• Cyclotron:
Previous…
PRC 21 2 (1980) 7Li(p,n),kT=25keV.Ep=1.912MeV,Ι=110μA
Φn=3⋅109n/son0.36cm2
Imax=200µA
Correc(ons
5MeV protons
Ι=30-50mA
70MeV protons, Ι=1.2mA
high intensity low-energy RIB by 238U(p,f)
TheLenosidea…
• Shaping the proton beam of the RFQ in order to obtain a desired neutron spectrum avoiding neutron moderaEon.
Firstapplica(on• MaxwellianneutronspectrumatkT=30keVwithhighspecificneutronflux
OVERVIEW
Multilayer Li target
Multilayer Energy Shaper
Sample
SPES RIB
RFQ
beam Chopper +
Wien Filter
DESIRED
NEUTRON
SPECRA
Beam Dump and Faraday Cup
P=164 kw P≈5 kw
Thefacility:(1/6)Mul(layerCarbonEnergyShaper
Conceptualdesign
Targetsurfacedividedintomanyareas,eachofthemwithadifferent(ckness.minimiza(onproceduretofitthenumber,(cknessandareaofeachlayerTicknessmeanprotonenergyofGaussian‐likedistribu(onAreaweightofthecorrespondingprotonenergydistribu(on
Thefinalshapeoftheprotonbeamisgivenbytheconvolu(onofthedifferentgaussian‐likedistribu(onweightedbytheocuupaiedarea.Thesametechiniquecanbeusedforapar(allythickLithiumtarget
Thefacility:(2/6)Mul(layerCarbonEnergyShaper
• With a rota(ng mul(layer carbon shaper is possible to obtain a neutron distribu(on with R2=0.999 respect to a Maxwelliandistribu(onatkT=30keV.
• IncaseofMaxwellianatkT=30keVispossibletoobtainadistribu(onwithR2=0.998usingamonolayercarbonshaperof152µmthickness.
• ItisacompromisebetweenR2,neutronyieldandcomplexity.
NIM
B 1
52 1
999
P=164kW for 50mA
ANSYS, Inc
• Deflec(onofprotonswithenergyunderthe7Li(p,n)7Bereac(onthreshold(1.88MeV).
• ReducedpowerdissipatedonLitarget.• Only5%ofprotonsontheLitarget.• BeamdumponCopperbacking
SRIM
Thefacility:(3/6)WienFilter
• ∼3kW/cm2couldbedissipated.Tli<152°C.Mel(ngpointat182°C.
• Li(30µm)onabackingofCu(1.5mm).• Microchannels,flowingHgliquidascoolantatT=‐20°CorGaSnI
alloyatT=15°C
Proton beam profile
Temperature of Li surface
ANSYS, Inc
Thefacility:(4/6)Lithiumtarget
RIB
1013 f/s
109-11 ion/s
• NeutronyieldsNIMB 152 (1999).
• AllsecondaryeffectsaccountwithMCNPXsimula(on.
Neutron Flux = 5⋅1010 n/s⋅cm2
NEUTRONS
SAMPLE • RIB implantation • Neutron irradiation
Thefacility:(5/6)Theresults…
Cyclotron Protons
70MeV, 1mA
238U target ALPI
Beam Selection
Li target Energy Shaper
Sample
SPES RIB RFQ
beam Wien Filter
• Tcarbon << Melting point. Radiation heat removing.
• 5 % proton beam, but no neutron moderation needed.
• It should be possible to dissipate P=3 kW/cm2 on Li.
• ANSYS calculation, Maximum Temperature (Li) ≈152ºC <TMelting = 180ºC
Thefacility:(5/6)Resume
NEUTRON
SPECRA
Thankyou