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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 ®ionalsystematics
[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.
Disclaimer:This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor anyagency thereof, nor any of their employees, makes any warranty, express or limited, or assumes any legal liability or responsibility for the accuracy,completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately ownedrights. Reference herein to any specific commercial product, process, or service by trade name, Page 3 of 3 trademark, manufacturer, or otherwise doesnot necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views andopinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.