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RecentresultsinNuclearAstrophysics@n_TOF,CERN
TaglienteGiuseppeIs#tutoNazionaleFisicaNucleare,Sez.diBari
(onbehalfofthen_TOFcollabora#on)
O. Aberle, J. Andrzejewski, L. Audouin, V. Becares, M. Bacak, J. Balibrea-Correa,M. Barbagallo, S. Barros, F. Becvar, C. Beinrucker, F. Belloni, E. Berthoumieux,J. Billowes, D. Bosnar, M. Brugger, M. Caamano, F. Calvino, M. Calviani, D. Cano-Ott , D. M. Castelluccio, F. Cerutti, Y. Chen, E. Chiaveri, N. Colonna, M. A. Cortes-Giraldo, G. Cortes, L. Cosentino, L. Damone, K. Deo, M. Diakaki, C. Domingo-Pardo,R. Dressler, E. Dupont, I. Duran, B. Fernandez-Domınguez, A. Ferrari, P. Ferreira,P. Finocchiaro, R. J. W. Frost, V. Furman, S. Ganesan, A. Gawlik, I. Gheorghe,T. Glodariu, I. F. Goncalves, E. Gonzalez, A. Goverdovski, E. Griesmayer, C. Guerrero,F. Gunsing, K. Gobel, H. Harada, T. Heftrich, S. Heinitz, A. Hernandez-Prieto, J. Heyse,G. Jenkins, E. Jericha, F. Kappeler, Y. Kadi, T. Katabuchi, P. Kavrigin, V. Ketlerov,V. Khryachkov, A. Kimura, N. Kivel, M. Kokkoris, M. Krticka, E. Leal-Cidoncha,C. Lederer, H. Leeb, J. Lerendegui, M. Licata, S. Lo Meo, R. Losito, D. Macina,J. Marganiec, T. Martınez, C. Massimi, P. Mastinu, M. Mastromarco, F. Matteucci,E. A. Maugeri, E. Mendoza, A. Mengoni, P. M. Milazzo, F. Mingrone, M. Mirea,S. Montesano, A. Musumarra, R. Nolte, A. Oprea, F. R. Palomo Pinto, C. Paradela,N. Patronis, A. Pavlik, J. Perkowski, J. I. Porras, J. Praena, J. M. Quesada, T. Rauscher,R. Reifarth, A. Riego-Perez, M. Robles, C. Rubbia, J. A. Ryan, M. Sabate-Gilarte,A. Saxena, P. Schillebeeckx, S. Schmidt, D. Schumann, P. Sedyshev, A. G. Smith,A. Stamatopoulos, S. V. Suryanarayana, G. Tagliente, J. L. Tain, A. Tarifeno-Saldivia,L. Tassan-Got, A. Tsinganis, S. Valenta, G. Vannini, V. Variale, P. Vaz, A. Ventura,V. Vlachoudis, R. Vlastou, A. Wallner, S. Warren, M. Weigand, C. Weiß, C. Wolf,P. J. Woods, T. Wright, P. Zugec
The n TOF Collaboration (http://www.cern.ch/ntof)
1
Then_TOFCollabora<on
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
(~100Researchersfrom30Ins2tutes)
CERN
TechnischeUniversitatWien Austria
IRMMEC-JointResearchCenter,Geel Belgium
CharlesUniv.(Prague) CzechRepublic
IN2P3-Orsay,CEA-Saclay France
KIT–Karlsruhe,GoetheUniversity,Frankfurt Germany
Univ.ofAthens,Ioannina,Demokritos Greece
INFNBari,Bologna,LNL,LNS,Trieste,ENEA–Bologna Italy
Univ.ofTokio Japan
Univ.ofLodz Poland
ITNLisbon Portugal
IFIN–Bucarest Rumania
CIEMAT,Univ.ofValencia,SanUagodeCompostela,UniversityofCataluna,Sevilla Spain
UniversityofBasel,PSI Switzerland
Univ.ofManchester,Univ.ofYork UK
Then_TOFCollabora<on
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
– Neutron cross sections relevant for Nuclear
Astrophysics
– Measurements of neutron cross sections relevant for Nuclear Waste Transmutation and related Nuclear Technologies (ADS)
– Neutrons as probes for fundamental Nuclear
Physics
n_TOFScien<ficMo<va<ons
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
n_TOF Goal
*** cross section uncertainties <5% *** safe control of systematic uncertainties
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
n_TOF Goal
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
PS 20GeV Linac 50 MeV
Booster 1.4 GeV
n_TOF 200m Tunnel
Proton Beam
20GeV/c
7x1012 ppp
Pb Spallation Target
Neutron Beam
10o prod. angle
Sample
The CERN n_TOF Facility
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
EAR-1:Horizontalflightpathof184.2m
Bothbeamlineshave:• 1stcollimatorforhalocleaningandfirstbeamshaping• Filtersta<on• Magnettominimizethechargedpar<clebackground• 2ndcollimatorforbeamshaping
EAR-2:Ver<calflightpathof18.2m
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
The n_TOF Facility: Beam lines
EAR-1 EAR-2
Wideenergyrange 25meV<En<1GeV 25meV<En<300MeV
Extremelyhighinstantaneousneutronflux 105n/cm2/pulse 106n/cm2/pulse
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
The n_TOF Facility: Main features
EAR-1 EAR-2
Wideenergyrange 25meV<En<1GeV 25meV<En<300MeV
Extremelyhighinstantaneousneutronflux 105n/cm2/pulse 106n/cm2/pulse
Lowrepe<<onrate <0.8Hz(1pulse/2.4smaximum)
Highresolu<oninenergy ΔE/E=10-4(En<10keV) ΔE/E=10-3(En<10keV)
UniquefacilityformeasurementsofradioacUveisotopesandlowcross-secUons:
• Branchpointisotopes(astrophysics)
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
The n_TOF Facility: Main features
ConceptbyC.RubbiaCERN/ET/Int.Note97-1919
97
ProposalsubmihedAu
g19
98
PhaseIIIsotopesCapture:14Fission:3(n,cp):2
2009
-20
12
Upgrades:Borated-H2OClass-ASecondLine
2010
ConstrucUonstarted19
99
2001-2004
PhaseIIsotopesCapture:25Fission:11
10 100 1000 10000 10000010-1
100
101
102
Res
pons
e (c
ount
s / n
s)
Neutron Energy / eV
n-TOF 232Th (0.0041 at/b) 208Pb
GELINA 232Th (0.0016 at/b) 208Pb
1995-1997 TARC
experiment
FeasibilityCERN/LHC/98-02+Add
May199
8
2000
CommissioningProblemInves<ga<on
2004-2007
NewTargetconstruc<on20
08
Commissioning
May2009
July2014
Commissioning
EAR2DesignandConstruc<on
2011
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
2015
Phase-3
n_TOFTimeline
151Sm204,206,207,208Pb,209Bi24,25,26Mg90,91,92,94,96Zr,93Zr139La186,187,188Os
n Crosssec<onsrelevantinNuclearAstrophysics
n s-process:branchingsn abundanciesinpresolargrainsn Magicnuclein Isotopesofpar<cularinteress
• In the period 2002-2004 measured long-needed capture and fission cross-sections for 36 isotopes, 18 of which radioactive.
• The unprecedented combination of excellent resolution, unique brightness and low background has allowed to collect high-accuracy data, in some cases for the first time ever.
TheexperimentalacUvityatn_TOF:PhI
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
54,56,57Fe58,60,62Ni,63Ni25Mg93Zr
n Crosssec<onsrelevantinNuclearAstrophysicsn s-process:seedsisotopes
In the period 2009-2012 measured long-needed capture and fission cross-sections for 22 isotopes, 14 of which radioactive.
TheexperimentalacUvity@n_TOF:PhII
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
Isot. R Comments
147Pm (n,γ) Branchingpoint26Al (n,p/α) 26Algalac<cabundance
7Be (n,p/α) ncaptureinlightnuclei
Isot. R Comments70,72,73Ge (n,γ) s-processflow171Tm,204Tl (n,γ) Branchingpoints88Sr,89Y (n,γ) NeutronMagic,1sts-
processpeek
AstroPhysicsprogram@EARI&EARII:PhaseIII
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
• There is need of accurate new data on neutron cross-sec<on forastrophysics.
• Since 2001, n_TOF@CERN has provided an important contribu<on to thefield,withanintenseac<vityoncaptureandfissionmeasurements.
• Severalresultsof interestforstellarnucleosynthesis (Sm,Ni,Os,Zr,Fe,Mgetc…).
• High resolu<on measurements performed in EAR1 in op<mal condi<ons(boratedwatermoderator,Class-Aexperimentalarea,etc…).
• TheEAR2hasopenednewperspecUvesforfron<ermeasurementsonshort-livedradionuclides.
Conclusions
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
Nucleus Nʘ
Normalized to
N(Si)=106 atoms
Ns/ Nʘ %
Old
Ns/ Nʘ %
n_TOF
90Zr 5.546 0.789 0.84491Zr 1.21 1.066 1.02492Zr 1.848 1.052 0.98194Zr 1.873 1.217 1.15296Zr 0.302 0.842 0.321
Thes-abundances,Ns,arecalculatedusingtheTPstellarmodelforlowmassAGBstar(1.5-3M¤).
Solarabundances,N¤,fromLodders2009,accuracy10%
CourtesyofR.GallinoandS.Bisterzio
Theexperimentalresults:Zrisotopes
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
Os)187()186(OsOs 186187
c187
σσ
−=
02.042.0)187()186(
±=σσ
Theexperimentalresults:186,187Os
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.
Tagliente–INFNBari
• Cosmological way
• Astronomical way
•
• Nuclear way: Re/Os clock Th/U clock
13.7±0.2Gyr
14±2Gyr
14.9±2Gyr(*)
(*)0.4Gyruncertaintyduetocross-sec<ons
14.5±2.5Gyr
Theexperimentalresults:186,187Os
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
s-Process150Sm 152Sm
151Eu 153Eu
152Gd 154Gd
Thebranchingra<ofor151Smdependson:• TermodynamicalcondiUonofthestellarsite(temperature,neutrondensity,etc…)
• Cross-sec<onof151Sm(n,γ)
151Smusedasstellarthermometer!!
151Sm
152Eu 154Eu
153Sm
Theexperimentalresults:151Sm
Laboratoryt1/2=93yrreducedtot1/2=3yr@s-processsite
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
Measured for the first time at a time-of-flight facility Resonance analysis with SAMMY code.
Maxwellian averaged (n,γ) cross section of the 151Sm and previous calculation (symbol)
NO PREVIOUS MEASUREMENTS!
Maxwellian averaged cross-section experimentally determined for the first time
s-processinAGBstarsproduces77%of152Gd,
23%frompprocess
Theexperimentalresults:151Sm
background
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
Scenariosinmassivestars
Theexperimentalresults:63Ni
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
63Ni (t1/2=100 y) represents the first branchingpoint in the s-process, and determines theabundanceof63,65Cu
Firsthigh-resoluUonmeasurementof63Ni(n,γ)intheastrophysicalenergyrange.
62Nisample(1g)irradiatedinthermalreactor(1984and1992),leadingtoenrichmentin63Niof~13%(131mg)
In 2011 ~15.4mg 63Cu in thesample(from63Nidecay).Aser chemical separa<on atPSI, 63Cu contamina<on <0.01mg
Theexperimentalresults:63Ni
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
IsotopeproducUon@ILL171Tm:170Er(n,γ)171Er(β-,7.5h)171Tm(enrichment1.8%)3.6mgof171Tm(1.9y)[1.3x1019atoms]ChemicalseparaUonandsamplepreparaUon@PSI171Tm(97.9%)+169Tm(2.1%)+170Tm(0.07%)
171Tmdeposit(20mmdiameter)
Frame(50mmdiameter)Mylar(5µm)
Aluminum(7µm)backing
1975
1980
1985
1990
1995
2000
2005
200
400
600
800
1000
1200
1400
637
1332
399
309 243
KADoNiS = 486
MACS@30keV(mb)
YEAR
Theexperimentalresults:171Tm(n,γ)
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
VERYPREL
IMINARYRES
ULTSFirst
experimentalmeasurement
Theexperimentalresults:171Tm(n,γ)
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
data:J.Lerendegui
Theneutroncapturecrosssec<ononGeaffectstheabundancesforanumberofheavierisotopesuptoamassnumberofA=90.
Theexperimentalresults:Ge(n,γ)
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
Theexperimentalresults:73Ge(n,γ)
ENDF/B-VIIn_TOF
ENDF/B-VIIn_TOF
VERYPREL
IMINARYRES
ULTS
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
data:C.Lederer
Theexperimentalresults:70Ge(n,γ)Co
unts
ENDF/B-VIIn_TOF
VERYPREL
IMINARYRES
ULTS
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
data:C.Lederer
Observa2onofthecosmicrayemi;er26Alisproofthatnucleosynthesisisongoinginourgalaxy.Theneutrondestruc2onreac2ons26Al(n,p)and26Al(n,α)arethemainuncertain2estopredictthegalac2c26Alabundance.Thereareonlyfewexperimentaldataonthesereac2onsandtheyexhibitseverediscrepancies.
26Al(n,p),(n,α)
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
26Al(n,p),(n,α)
ThepandαwillbedetectedbydoublesidedsiliconstripdetectorsarrangedasE–ΔEtelescope
ThesamplewasproducedbyIRMMincollabora<onwithLANCSE
Theneutronfluencewillbemonitoredbya10Bsample
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
BBNsuccessfullypredictstheabundancesofprimordialelementssuchas4He,Dand3He
Aseriousdiscrepancy(factor2-4)betweenthepredictedabundanceof7Liandthevalueinferredbymeasurements
CosmologicalLithiumProblem
7Be(n,p),(n,α)
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
Approximately95%ofprimordial7Liisproducedfromtheelectroncapturedecayof7Be(T1/2=53.2d)
7Beisdestroyedvia(n,p)(≈97%)and(n,α)(≈2.5%)reac<ons
Ahigherdestruc<onrateof7Becansolveoratleastpar<allyexplaintheCosmologicalLithiumProblem
7Be(n,p)
7Be(n,α)
Onlyonedirectmeasurement(P.Bassietal.,1963,@0.025eV)
7Be(n,p),(n,α)
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
neutrons
Silicon 1
Silicon 2
sample
SandwichofsilicondetectorsdirectlyinsertedinthebeamDetec<onofbothalphapar<cles(E≈9MeV)
Coincidence technique: Strong rejection of background
Sample: 1.4 µg of 7Be from water cooling of SINQ spallation target. (activity of 478 keV γ-rays)
Isotopic composition: 1:1 7Be-10Be 1:5 7Be-9Be
7Be(n,α)
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
IntrinsicdifficultyofthemeasurementlowcrosssecUonextremelyhighspecificacUvity:13GBq/µgavailableinsmallquanUtyshorthalf-life:53.3days
7Be(n,α)cross-secUon
§ 1/vbehaviourofthe7Be(n,α)4HereacUoncross-secUon.§ Theonlypreviousmeasurement(@0.025eV)isingoodagreementwithnewdata
CourtesyofM.Barbagallo
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
Acceptedb
yPRL
Telescopeofsilicondetectors(E–DE)Detectedproton(E≈1.6MeV)
7Be(n,p)
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
p
𝐸 ∆𝐸 NeutronbeamHighpuritysampleneeded:
PSI+ISOLDE1.1GBqacUvityofthesample
protondiffusion
13C(α,n)16O
22Ne(α,n)25Mg-C
10-4
neutronde
nsity
<me
neutronde
nsity
<me
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari
Spinassignmentandconstraintsfor22Ne(α,n)25Mg
ThisworkER=72keV,Jπ=2+ER=79keV,Jπ=3-
LibraryER=72keV,Jπ=2+ER=79keV,Jπ=3+
The25Mgisoneofthemostimportantneutronpoisoninthes-processpath.
ResonanceAnalysis:simultaneousanalysisoftransmission(GELINA)andcapturedata(n_TOF)
Theexperimentalresults:25Mg(n,γ)
The22Ne(α,n)isoneofthemainsourceofneutronsforthes-process.Extremelydifficulttomeasure(verylowcrosssec<on).ReacUonrateveryuncertainbecauseofthepoorlyknownpropertyofthestatesin26Mg.
Interna<onalNuclearPhysicsConference–Adelaide,September11-16,2016G.Tagliente–INFNBari