Example of Evaluation: Decay of 177Lu 6.647 d

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Example of Evaluation Decay of 177Lu (6.647 d)

• Filip G. Kondev
• kondev_at_anl.gov

2nd Workshop for DDEP Evaluators, Bucharest,
Romania May 12-15,2008
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Outline

• Introduction
• nuclear structure properties of 177Lu
• the relevance to applications
• Nuclear Data Properties
• lifetime
• beta and gamma-ray emission probabilities
• Atomic Data
• Guidelines for Evaluators

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Nuclear Structure Properties of 177Lu

• deformed rare-earth nucleus with 71 protons and
  106 neutrons

Q(7/2) 3.39(2) eb m(7/2) 2.239(11) mN
Q(b-)500.6(7) keV
G.Audi et al, Nucl. Phys. A729 (2003) 337
Q(23/2-) 5.2(5) eb m(23/2-) 2 .337(13) mN
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Why of interest to applications

• 177Lu (6.647 d) is a therapeutic radionuclide
• used to cure the so-called metastatic bone
  disease when breast or prostate cancer spreads
  from their primary sites to the bone the cure
  is to use high-energy b- particles to the bone

• 177mLu (160.44 d) can be used as g-ray energy
  efficiency standards (high multiplicity) has a
  potential for energy related applications (e.g.
  energy storage device)
• gamma-ray tracking, where the efficiency depends
  on g-ray multiplicity

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Nuclear Data

• Q(b-)
• G. Audi et al, Nucl. Phys. A729 (2003) 337
• http//www.nndc.bnl.gov/qcalc/
• Lifetime
• need to be evaluated
• Emission energies probabilities (b- and g)
• need to know the decay scheme - adopted Ex, Jp,
  mult (ENSDF)
• aT use BRICC (see talk by T. Kibedi)
• evaluate Eg, Pg, d, Pb-
• calculate Eb-, max, log ft

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Production of 177Lu
s(n,g)3.02 (5) b

• no contaminants
• small production CS

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Lifetime measurements

• usually follow several T1/2
• statistical uncertainties are usually small
• systematic uncertainties (dead time, geometry,
  etc.) dominate, but often these are not reported

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Half-life of 177Lu

• not a trivial task depends on the main
  production mode all measurements used
  176Lu(n,g)177Lu production

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Half-life of 177Lu - cont
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T1/2 6.7479 (7) d
208.4
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(No Transcript)
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Half-life of 177Lu
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• What we want to know accurately
• T1/2, Eg, Ig, mult d aT

• Eg determines Ex and Eb
• Ig, mult., d aT determine Pb(g)

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Gamma-ray energies example
Lweight
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Gamma-ray intensities example
Lweight
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Gamma-ray mixing ratios example
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Itot(137)Itot(208)11.19 (7)
Itot(113)20.29 (7)
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log ft values

• ENSDF analysis program LOGFT both Windows
  Linux distribution

http//www.nndc.bnl.gov/nndcscr/ensdf_pgm/analysis
/logft/

• LOGFT Web interface at NNDC

http//www.nndc.bnl.gov/logft/
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7/2?13/2- DI3 pipf-1 3rd forbidden
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Using RADLST
Consistency 0.18
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Atomic Data
g-ray
K
L
X-ray
M
Energetics of CE-decay (iK, L, M,.)
Ei Ef Ece,i EBE,i Tr

• emission of X-rays
• emission of Auger electrons

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Where Data Come From?

• The X-ray energies J.A. Bearden, Rev. Mod.
  Phys. 39 (1967) 78 (also TOI)
• Fluorescence yields
• wK 1 (Zgt35) to 10 (Z5) -W. Bambynek et al.
  Rev. Mod. Phys. 44 (1972) 716
• wL lt 4 (Zgt29) - E. Schonfeld and H. Janssen,
  PTB-Report RA-37 (1995)
• wM J.H. Hubbell et al., J. Phys. Chem. Ref.
  Data 23 (1994) 339 (fit to expt. data)
• Relative Kb/Ka and Ka1/Ka2 emission rates (lt1
  assumed)
• from E. Schonfeld and H. Janssen, PTB-Report
  RA-37 (1995) and J.H. Scofield, Phys. Rev. A9
  (1974) 1041, respectively
• The K- and L-Shell Auger electron energies
• F.P. Larkins, ADNDT 20 (1977) 313
• Emission probabilities of K-shell Auger
  electrons
• deduced from X-ray ratios- E. Schonfeld and H.
  Janssen, PTB-Report RA-37 (1995)

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Guideline for evaluators

• Start with the examination of the known decay
  scheme
• use ENSDF for Jp, mult., etc. as a first
  approximation but check for latest references
  using the NSR database and be aware of potential
  differences create your own ENSDF file you
  can use some useful ENSDF programs (ALPHAD,
  BRICC, GABS, GTOL, LOGFT, RADLST)
• Use Q values from G. Audi et al. mass evaluation
  (2003Au03)
• Evaluate T1/2, Ig, mult., aT d following DDEP
  rules
• use LWEIGHT for statistical analysis of data
• Deduce level energies using evaluated transition
  energies, e.g. Eg /- DEg, etc. (using GTOL for
  example)
• Do the intensity balances of the decay scheme
  and deduce Pb, Pa, Pg, etc. for each level
  (transitions)

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Guideline for evaluators-cont.

• Calculated log ft and/or HFa values (using
  LOGFT and ALPHAD)
• Estimate possible week branches (or missing
  ones) using systematics of log ft and/or HFa
  values get Pb and/or Pa
• Check the decay scheme for consistency (using
  RADLST)

• Get the atomic data using the EMISSION program
• need to provide Eg/-DEg, Pg/-DPg and aK, aL,
  aM, aN etc (and their uncertainties)
• compare with experimental data, if any, for
  consistency
• Get Ebmax and Eb av. using LOGFT program

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Some personal notes

• Be critical to the experimental data you are
  dealing with!
• as all nuclei are different, so are the
  experiments

• A good evaluation is not just simply averaging
  numbers!
• sometime the most accurate value quoted in the
  literature is not the best one!

• Enjoy what you have been doing!