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Neutron Activation Decay Data Richard B. Firestone Isotopes Project, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 DDEP Workshop 8-10 October.

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Presentation on theme: "Neutron Activation Decay Data Richard B. Firestone Isotopes Project, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 DDEP Workshop 8-10 October."— Presentation transcript:

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2 Neutron Activation Decay Data Richard B. Firestone Isotopes Project, Lawrence Berkeley National Laboratory, Berkeley, CA DDEP Workshop 8-10 October 2012

3 The Evaluated Gamma-ray Activation File (EGAF) The EGAF database was developed to manage the first measurements of prompt and delayed  -ray cross sections at the Budapest Reactor. These data were compiled under an IAEA CRP and are available in Database of Prompt Gamma Rays from Slow Neutron Capture for Elemental Analysis, R.B. Firestone, et al, IAEA STI/PUB/1263, 251 pp (2007). Handbook of Prompt Gamma Activation Analysis with Neutron Beams, edited by G.L. Molnar (Kluwer Publishers, 2004). EGAF Contents E ,   for prompt  -rays from thermal (n,  ) on all isotopic targets E ,  , t 1/2, for  -rays from all thermal (n,  ) activation products   derived from   data and other measurements Adopted Levels, Gammas, S n for all (n,  ) product nuclei (RIPL)

4 Evaluation of Neutron Activation Products The Evaluated Gamma-ray Activation File (EGAF) contains adopted decay data for all activation products. I propose that these data be evaluated under DDEP guidelines. Important for reactor decay heat calculations Important for neutron transport calculations Important for neutron activation analysis (NAA) Important for national security and nonproliferation Important for nuclear medicine Special decay scheme normalization constraints 303 Isotopes, 81 isotopes evaluated by DDEP

5 Activation Product List DDEP evaluated

6 Data Resources Cross sections EGAF activation product  ,   IUPAC NAA k 0 compilation Mughabghab  , Atlas of Neutron Resonances Literature Radioactive decay data DDEP evaluations ENSDF evaluations XUNDL compilations Literature Decay energies Audi atomic mass evaluations

7 Decay Scheme Normalization   =   (GS)=   (CS)   =   /P  If   is determined from prompt   or other data and decay   is known, then P  is uniquely determined. Both   and   can be measured in the same experiment.

8 Determination of   1.Z<20 decay scheme complete   =   (GS)=   (CS) 2. Z≥20 must correct for continuum Continuum – calculated with statistical model code DICEBOX Below E crit – measured primary, secondary  -rays from EGAF. Level scheme from ENSDF, modified to RIPL standard and consistency with DICEBOX   =   (GS) expt +   (GS) calc

9 Population/Depopulation Plots Comparison of cross sections populating levels (DICEBOX) and depopulating them (EGAF) helps chose statistical model parameters.

10 Improved Adopted Level Properties J  =    based upon  (t) in 104 Ru(α,2n  ) is inconsistent with   from statistical model calculations. Further investigation indicates adopted J  is based on weak partially obscured  - rays and inconsistent with  -ray decay to   levels.

11 Determination of    P  : 24 Na 540.9(25) b 543.3(35) b 478(4) mb PGAA 540(4) mb S N g Na Author (year)  0 ±  (mb) Coltman (1946)0.47±0.04 Pomerance (1951)0.470±0.024 Meadows (1961)0.47±0.06 Brooksbank (1955)0.50±0.05 Koehler (1963)0.50±0.02 Yamamuro (1970)0.50±0.03 Harris (1953)0.503±0.005 Grimeland (1955)0.51±0.03 De Corte (2003)0.513±0.006 Kennedy (2003)0.515±0.021 Heft (1978)0.523±0.005 Ryves (1970)0.527±0.005 Szentmiklosi (2006)0.527±0.008 Bartholomew (1953)0.530±0.032 Wolf (1960)0.531±0.008 Cocking (1958)0.536±0.006 Jowitt (1959)0.536±0.008 Rose (1959)0.539±0.008 EGAF-PGAA0.540±0.004 EGAF-NAA0.542±0.003 Gleason (1975)0.54±0.02 Kaminishi (1963)0.577±0.008 Seren (1947)0.63±0.13 Atlas0.517±0.004 Summing problems May have affected previous values.

12 Determination of    P  : 41 K S N PGAA 1.62(3) b 0.269(5) b Author (Year)  0  (mb)   (1525) Seren (1947)1.0±0.2 Pomerance (1952)1.19±0.10 Koehler (1967)1.2±0.1 Gryntakis (1976)1.28±0.06 De Corte (2003)1.42± (2) Gleason (1975)1.43± (5) Heft (1978)1.43± (5) Lyon (1960)1.45 Ryves (1970)1.46±0.03 Kappe (1966)1.49± (8) Kaminishi (1982)*1.57±0.17 EGAF1.62± (5) Atlas1.46±0.03 Author (Year)P  (1566) Miyahara (1990)*0.1808(9) Simoes (2001)* (14) EGAF0.164(4) * 4  measurement not corrected for self-absorption in the target. A significant problem may exist with P  values measured by 4 . Many   values were measured this way * 4  Corrected for self-absorption

13 Determination of   /P  : 109 Pd E  (keV)   (IUPAC) P  (IUPAC)P  (DDEP) (1) (3) (21) (4) (18) (14) For   (EGAF)=8.6(6) b (   (Atlas)=7.6(5) b)

14 Conclusions EGAF database provides an opportunity to evaluate a complete thermal neutron activation database Evaluations should be consistent with DDEP standards Addition of   cross sections Improved P  measurements Move towards a common decay data evaluation standard for all databases (EGAF, ENSDF, DDEP) - discussion

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