StatisticalPropertiesofNucleiFarfromStabilityforNational

SecurityApplicationsAdrianaUreche

DepartmentofNuclearEngineeringUniversityofCalifornia,Berkeley,

May10,2017

6th OsloWorkshopofNuclearLevelDensity&GammaStrength

A.Ureche

Fissionproductsinafissionenvironment

Meeting Isotope Needs and Capturing Opportunities for the Future: The 2015 Long Range Planfor the DOE-NP Isotope Program, NSAC Isotopes Subcommittee, July 20, 2015

Future:DevelopedapproacheswillbeimplementedattheFacilityforRareIsotopeBeam(FRIB)toexplorethelimitsoftheknownnuclides.

A.Ureche

Fissionproductsinafissionenvironment

Meeting Isotope Needs and Capturing Opportunities for the Future: The 2015 Long Range Planfor the DOE-NP Isotope Program, NSAC Isotopes Subcommittee, July 20, 2015

Future:DevelopedapproacheswillbeimplementedattheFacilityforRareIsotopeBeam(FRIB)toexplorethelimitsoftheknownnuclides.

A.Ureche

Fissionproductsinafissionenvironment

Meeting Isotope Needs and Capturing Opportunities for the Future: The 2015 Long Range Planfor the DOE-NP Isotope Program, NSAC Isotopes Subcommittee, July 20, 2015

92Sr2.66h

n,γ

Future:DevelopedapproacheswillbeimplementedattheFacilityforRareIsotopeBeam(FRIB)toexplorethelimitsoftheknownnuclides.

A.Ureche

Determiningthe92Sr(n,γ)CrossSection

93Sr7.43m

93Rb5.84s

93Y10.18h

92Sr2.66h

β

β

n,γ

93Zr1.6E6y

β

Challenges:• Compound nucleus 93Sr can not

be formed through neutroncapture due to the short half lifeof 92Sr

• β-decay is a very selective decay,populating levels with spin of0 ≤ ∆J ≤ 1 and no change inparity

Experiment Spring 2018:• NSCL – National Superconducting

Cyclotron Lab – will provide athermal beam of 93Rb

• Coincidence measurements withthe Summing NaI (SuN) detector& a plastic β-particle scintillator

A.Ureche

Determiningthe92Sr(n,γ)CrossSection

93Sr7.43m

93Rb5.84s

93Y10.18h

92Sr2.66h

β

β

n,γ

93Zr1.6E6y

β

Challenges:• Compound nucleus 93Sr can not

be formed through neutroncapture due to the short half lifeof 92Sr

• β-decay is a very selective decay,populating levels with spin of0 ≤ ∆J ≤ 1 and no change inparity

Experiment Spring 2018:• NSCL – National Superconducting

Cyclotron Lab – will provide athermal beam of 93Rb

• Coincidence measurements withthe Summing NaI (SuN) detector& a plastic β-particle scintillator

A.Ureche

β-OsloMethod

1.Unfoldthedetectorresponse

2.Firstgenerationextracted

3.NLD&γSF

extracted

4.NormalizeNLD&γSF

SummingNaI(Tl)(SuN)DetectorMichiganStateUniversity[A.Simon,S.J.Quinn,A.Spyrou,etal.,NIMA703(2013)16-21]

CACTUSUniversityofOslo[M.Guttormsen,B.Bjerke,J.Kownacki,S.Messelt,E.A.Olsen,T.Ramsøy,J.Rekstad,T.S.Tveter andJ.C.Wikne1989CACTUS- Amultidetector set-upattheOslocyclotron DepartmentofPhysicsReport (Univ.ofOslo,Oslo)89-14]

A.Ureche

β-OsloMethod1.Unfold

thedetectorresponse

2.Firstgenerationextracted

3.NLD&γSF

extracted

4.NormalizeNLD&γSF

β-Decay of 76Ga resulting themeasured γ-rays emitted by 76Ge[A.Spyrou etal.,Phys.Rev.Lett.113,232502

(2014)]

76Ge

E x(keV

)

Eγ (keV) Eγ (MeV)

E x(M

eV)

12

10

8

6

4

2

89Y

Charged particle reaction:89Y(p,p’γ)

[A.C.Larsenetal.,Phys.Rev.C93,045810(2016)]

SpinDistribution

A.Ureche

J

RelativeIntensity

β-decayof93Rb92Sr(d,p)–5MeVdeuteron

β-decay: probability isdescribed by Gamow-Teller Allowed DecaysΔJ =0,1 Δ π =no

92Sr(d,p)- 5MeVdeuteron: dependsonthespincutoffparameter

Themethodofexcitinganucleusbyβ-decaycoversasimilarspinrangecomparedtoachargesparticlereaction,butitmissesthehighspinstates.

RadioactiveBeam:93Rb

A.Ureche

• Countrateseenbydetectorsystem:R=2s-1• ~10%oftheβ-decayswillpopulatehighly-

excitedstatesof93Srwithin1MeVoftheneutronseparationenergy,Sn =5.29MeV

93Rb

SuN

β-particledetector

tape

Tape &MotorBox

93Rb

93Sr

93Y

β-

β-

t1/2=5.84(2)s

t1/2=7.43(3)m

t1/2=10.18(8)h

RemovalTime(s)

Contamina-tion (%)

EventRate(s-1)

300 16.39 1.94120 7.61 1.8660 3.85 1.7230 1.84 1.4520 1.18 1.2410 0.56 0.83

ExperimentalSet-up

A.Ureche

Summing Sodium Iodine (NaI) Detector• 85% efficiency for a 137Cs source

(Eγ = 661 keV)• High efficiency for γ rays• 16-in diameter x 16-in length• 8 optically isolated NaI segments• Photomultipliertubes

(3perNaI segment)• Bore hole (45 mm in diameter)

Plastic β-particle scintillator• 30% total efficiency• Length of 8-in• Located at center of SuN

ExperimentalSet-up

A.Ureche

Summing Sodium Iodine (NaI) Detector• 85% efficiency for a 137Cs source

(Eγ = 661 keV)• High efficiency for γ rays• 16-in diameter x 16-in length• 8 optically isolated NaI segments• Photomultipliertubes

(3perNaI segment)• Bore hole (45 mm in diameter)

Plastic β-particle scintillator• 30% total efficiency• Length of 8-in• Located at center of SuN

ExperimentalSet-up

A.Ureche

Summing Sodium Iodine (NaI) Detector• 85% efficiency for a 137Cs source

(Eγ = 661 keV)• High efficiency for γ rays• 16-in diameter x 16-in length• 8 optically isolated NaI segments• Photomultipliertubes

(3perNaI segment)• Bore hole (45 mm in diameter)

Plastic β-particle scintillator• 30% total efficiency• Length of 8-in• Located at center of SuN

ExperimentalSet-up

A.Ureche

Summing Sodium Iodine (NaI) Detector• 85% efficiency for a 137Cs source

(Eγ = 661 keV)• High efficiency for γ rays• 16-in diameter x 16-in length• 8 optically isolated NaI segments• Photomultipliertubes

(3perNaI segment)• Bore hole (45 mm in diameter)

Plastic β-particle scintillator• 30% total efficiency• Length of 8-in• Located at center of SuN

A.Ureche

DICEBOXsimulated93Sr

Nuclear data libraries contain no experimentally determined:• Nuclear Level Density• Giant Dipole Resonance• Neutron Resonance parameters

Emittedγ-rays

(DICEBOX)

Detectorresponse(GEANT4)

ExtractNLDandγSF(β-Oslo)

ConstantTemperature(CT)Formula

RIPL-3LeveldensityatSn &regionalsystematics

[MeV]xE0 1 2 3 4 5 6 7

)-1

(MeV

ρ

1−10

1

10

210

310

Level Density

A.Ureche

InvestigatingNuclearLevelDensityEvaluatedNuclearStructureDataFile(ENSDF)reports91measuredlevels,74%arefromβ-Decaymeasurements

AdoptedLevelsCTFvonEgidy &Bucurescu[PRC80,054310(2009)]

Sn =5.290(8)MeVρ(Sn)=2665.8 MeV-1

𝜌"# =𝑒('()'*)/#

𝑇

DICEBOX

A.Ureche

Summary&FutureWork• Analyzed a simulated data set of γ rays emitted by 93Sr to predict the

experimentally-observed behavior

• Investigating the contribution of different initial Jπ to the Nuclear Level Density

• Fold in the response function of the SuN detector to the simulated emitted γ rays

• Motor and tape box is completed, but needs more testing of moving parts and

detectors (MSU)

• Experiment: SPRING 2018!

GasStoppingCell

SuN

A.Ureche

UCBerkeley- B.L.Goldblum,J.Vujic

LBNL- L.A.Bernstein

LLNL- D.L.Bleuel,N.D.Scielzo

MSU&NSCL- A.Spyrou,M.K.Smith,F.Naqvi,S.N.Liddick,K.Leslie,D.Lawton,A.Dombos,C.Harris,A.Palmisano,D.Richman

UniversityofOslo- A.C.Larsen,M.Guttormsen

Acknowledgement

This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344and Lawrence Berkeley National Laboratory under Contract No. DE-AC02-05CH11231. This material is based upon work supported by the Department ofEnergy National Nuclear Security Administration through the Nuclear Science and Security Consortium under Award Number DE-NA0003180.

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