Horizontal Evaluation
(Topical Review) on
K-Isomers in Deformed Nuclei
kondev@anl.gov
Filip G. Kondev
Nuclear Engineering Division
Outline
 Introduction & Motivation (very brief!)
 Present Status & Outlook
17th NSDD Network meeting, St. Petersburg, Russia, 2007
Introduction & Motivation
long-lived states due
to conservation of the
K quantum number
w Kf=0 j
2
j1
j
Ki
Probe various aspects of nuclear structure at extreme conditions:
 interplay between intrinsic & collective motion
 limits of conservation of K-quantum number (robustness of symmetry)
 seniority dependence of major residual interactions in deformed nuclei
Exotic nuclear structure studies:
 radioactive targets – high-spin/seniority – e.g. 178mHf, 177mLu
 radioactive beams – the future – physics at extreme conditions
Potential for many applications:
Astrophysics, Activation analysis; Medicine; Detector calibration
standards; Nuclear energy
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K Isomers: Where to find them?
 Deformed nuclei with axially-symmetric shape
Mass 180 region : Yb (Z=70)-Ir(Z=77)
w
j2
j1
j
K
 High-K orbitals near the Fermi surface
 5/2[402], 7/2[404], 9/2[514]
n 5/2[512], 7/2[514], 7/2[633], 9/2[624]
7-qp
K=49/2
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The Best Known Isomer …
Jag has been always in an
excited state!
and
he will have a
very long lifetime!
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Isomers Research at Argonne
 Availability of a variety of HI beams and a flexible beam pulsing system
 from 4He up to 238U/ time-range from ns up to years!
 Existence of high-efficiency detector systems, e.g. Gammasphere & FMA
Studying Isomers at extreme conditions:
Heavy nuclei/ Proton Drip Line/ Neutron Rich Nuclei/High-spin & Seniority
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K-Isomers Evaluation
 Aim – to evaluate properties of all K-isomers in deformed
nuclei – including Ex, K, J, T1/2, BR, ICC, B(XL) and fn - no
such systematic study exists, but it is very much needed!
 Why not using ENSDF directly?
 we (in ENSDF) don’t treat explicitly the K-quantum
number
 long updating time (6-8 years)
(I,K)i
(I,K)f
Eg(Xl)
for M1 and E2 decays
20< fn <100 - K-hindered decay
fn<10 - anomalous decay
fv>100 – perhaps something is wrong!
n=DK-l – degree of K-forbiddenness
F=tg(Xl)/tw(Xl) – hindrance factor
fn=(F)1/n – reduced hindrance per
degree of K-forbiddenness – gives
yardstick for “goodness” of the Kquantum number
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K-Isomers Evaluation-cont.
 The data are evaluated in ENSDF format
have agreed on general policies – tried to follow the ENSDF policies as
much as possible
specialized codes were developed
 The evaluation will be completed in the next 1-2 years and
it will be made available to all NSDD centers and published
 can easily be used to update ENSDF
will make specific recommendations to improve ENSDF – introduction
of the K-quantum number explicitly
 it will be continuously updated
 the need to include other classes of isomers – will depend on the needs
of the community
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K-Isomers Evaluation-cont.
 Prediction of energies, J – OK: WS (Nilsson) with pairing
 Prediction of T1/2? – not so good!
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Collaborators
T. Kibedi & G.D. Dracoulis
Australian National University, Canberra, Australia
Encouragement and advice from many colleagues:
R. Janssens (ANL), P. Chowdhury (UML), P. Walker (U. Surrey),
and others
Supported by the Office of Nuclear Physics, U.S. DOE
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