recent results in nuclear astrophysics @ n tof, cern · recent results in nuclear astrophysics @...

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


–  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


n_TOF Goal

*** cross section uncertainties <5% *** safe control of systematic uncertainties


n_TOF Goal


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


EAR-1:Horizontalflightpathof184.2m

Bothbeamlineshave:•  1stcollimatorforhalocleaningandfirstbeamshaping•  Filtersta<on•  Magnettominimizethechargedpar<clebackground•  2ndcollimatorforbeamshaping

EAR-2:Ver<calflightpathof18.2m


The n_TOF Facility: Beam lines

EAR-1 EAR-2

Wideenergyrange 25meV<En<1GeV 25meV<En<300MeV

Extremelyhighinstantaneousneutronflux 105n/cm2/pulse 106n/cm2/pulse


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)


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


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


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


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


•  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


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


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


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


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


Scenariosinmassivestars

Theexperimentalresults:63Ni


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


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)


VERYPREL

IMINARYRES

ULTSFirst

experimentalmeasurement

Theexperimentalresults:171Tm(n,γ)


data:J.Lerendegui

Theneutroncapturecrosssec<ononGeaffectstheabundancesforanumberofheavierisotopesuptoamassnumberofA=90.

Theexperimentalresults:Ge(n,γ)


Theexperimentalresults:73Ge(n,γ)

ENDF/B-VIIn_TOF

ENDF/B-VIIn_TOF

VERYPREL

IMINARYRES

ULTS


data:C.Lederer

Theexperimentalresults:70Ge(n,γ)Co

unts

ENDF/B-VIIn_TOF

VERYPREL

IMINARYRES

ULTS


data:C.Lederer

Observa2onofthecosmicrayemi;er26Alisproofthatnucleosynthesisisongoinginourgalaxy.Theneutrondestruc2onreac2ons26Al(n,p)and26Al(n,α)arethemainuncertain2estopredictthegalac2c26Alabundance.Thereareonlyfewexperimentaldataonthesereac2onsandtheyexhibitseverediscrepancies.

26Al(n,p),(n,α)


26Al(n,p),(n,α)

ThepandαwillbedetectedbydoublesidedsiliconstripdetectorsarrangedasE–ΔEtelescope

ThesamplewasproducedbyIRMMincollabora<onwithLANCSE

Theneutronfluencewillbemonitoredbya10Bsample


BBNsuccessfullypredictstheabundancesofprimordialelementssuchas4He,Dand3He

Aseriousdiscrepancy(factor2-4)betweenthepredictedabundanceof7Liandthevalueinferredbymeasurements

CosmologicalLithiumProblem

7Be(n,p),(n,α)


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)


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)


IntrinsicdifficultyofthemeasurementlowcrosssecUonextremelyhighspecificacUvity:13GBq/µgavailableinsmallquanUtyshorthalf-life:53.3days

7Be(n,α)cross-secUon

§  1/vbehaviourofthe7Be(n,α)4HereacUoncross-secUon.§  Theonlypreviousmeasurement(@0.025eV)isingoodagreementwithnewdata

CourtesyofM.Barbagallo


Acceptedb

yPRL

Telescopeofsilicondetectors(E–DE)Detectedproton(E≈1.6MeV)

7Be(n,p)


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


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.


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