Extension of integral validation tools

1. FENDL-3 Vienna December 6-9, 2011 Extension of integral validation tools J. KopeckyJUKO Research, the Netherlands

2. Scope of the presentation • Motivation • The status of integral validations • The novel use of 30 keV capture data • Conclusions

3. EAF special features • A compact database of integral activation experiments ranging from 0.0253 eV up to 30 MeV. Allows a detail comparison of the XS response against differential and integral experiments – integral experiments • The most complete database of capture cross sections, covering all 816 targets. A special approach has been applied for reactions with no experimental information. This includes the present and future use of 30 keV data - 30 keV averaged cross sections

4. Integral measurements

5. Integral measurements • The set of integral activation data was used for validation of EAF-2003, 2005 and2007 (see UKAEA FUS 547/2008/) and has been recently used to validate data from EAF-2010, TENDL-2009 and TENDL-2010 (see EAF-Doc-54,55 and JEF-Doc-1368) • The data set includes 484 reactions measured with 8 + 1 different neutron spectra, see next slide • Quasi mono-energetic data (e.g. 22.5 MeV of d-Be source) interpreted as integral measurements • C/E comparison is based on effective cross-sections formalism (R. Forrest)

6. Neutron spectra

7. Integral measurements observations • Important : The 14 MeV integral activation experiments validate only cross sections at < 14 MeV – relevant for 14 MeV applications (fusion). Sometimes only a small part of the excitation curve (close to the threshold) is covered • To validate the data above 14 MeV (for many reactions the major component of the excitation curve) a broader neutron spectrum is needed (e.g. d-Be, p-D etc.) • Some reactions have satisfactory (or good) agreement with differential and unsatisfactory agreement with integral data. The experience shows, that this indicates often a suspicious result of the integral experiment or the ‘local’ effect (see next) • Another observation is that the overall visual improvement of the data fit with differential data sometimes worsens the C/E value, especially if the neutron spectrum covers only a small part of the excitation curve. This explains that C/E(EAF-2005) value is sometimes better, however, with not a good overall agreement

8. The 30 keV capture Cross Sections • Three important cross sections for capture cross section components : 1/v (s(th)), statistical (s(30 keV) and PEQ (s(14 MeV)

9. Status of 30 keV capture Cross SectionsPresently used in EASY-2010 system • Karlsruhe - Compilations of Maxwellian averaged XS (MACS) for astrophysics – KfK (1987) and (2000) - recent (2007) KADoNiS data base – interpreted as quasi-monoenergetic value • EAF - MACS (2000) used in EAF for RN and C/E validation assuming MACS -> +s(30 keV) • Supporting tools: 1. XS(30 keV) systematic derived and used C/S 2. Isotopic MACS dependence used as additional check to identify suspiciously wrong values

10. Maxwellian Average Cross Section MACS The definition of MACS as velocity distribution used in astrophysics compilations

11. The MACS experimental input • The activation measurementin MB- like neutron spectrum from (p,Li-6) reaction • Theneutron spectrum correction is defined as F = sexp/seval and determined by folding the library s(eval) with the experimental 30 keV neutron spectrum Then s(En ) in <sv>/vT formula for MACS is replaced by seval(En) * F • TOF absolute data (in b) folded with theoretical Maxwellian and using <sv>/vT formula

12. Experimental energy distribution of Li-7(p,n) reaction

13. 30 keV capture XS systematic

14. s(30 keV)performence in EAF-2010

15. Isotopic dependence of 30 keV s(n,g) far from closed shell near closed shell

16. MCNPX calculation by L. Packerneutrons born in carbon (the scattering medium at kT = 30 keV) with r = 10m

17. Analytical MB velocity distribution calculated by R. Forrest

18. MB theory vs MCNPX

19. Folding procedure of 30 keV cross sections in Vitamin-J 175 groups 30keV

20. Point-wise vs averaged cross sections at 30 keV • A similar approach, as for 0.0253 eV cross sections, was applied comparing the cross section measured at thermal velocity vo = 2200m/sec to the Maxwellian cross section • It can be shown (e.g. BNL barn book and references there) that if the cross section is exactly proportional to 1/v behaviour, then the Maxwellian cross section is equivalent to the point-wise s (v) value at 0.0253 eV • In many cases, due to presence of nearby resonances, the cross section s (v) does not vary exactly as 1/v. An effective cross section introduced was by Westcott, where Westcott factors take care of the non-1/v behaviour

21. Point-wise vs averaged cross sections at 30 keVSupports previous use of MACS for RN

22. EAF-2010 vs MACS (KADoNiS)

23. Data outliers SRA RR

24. Ratio of MB averaged cross-sectionsEAF <Iav> vs MACS ratio

25. Outlier classes • Simplified (no RR) excitation curve – uncertainty in EV=EH • Shape vs MACS value

26. Outlier classes • New RR? Not in MACS? EAF-2007 vs EAF-2010

27. Test of resonance regions EAF-2010 = JENDL-4.0 <EAF>/KADoNiS = 1.06 C/E (Ires) = 1.08 ENDF/B-VII <ENDF>/KADoNiS = 2.54 C/E (Ires) = 1.06

28. Heil M et al. PRC77-015808 (2008) Li-7(p,n) source Ni-64 (n,g) <s(30 keV)> = 8.4(3) mb F = 0.38 JEFF-3.1 F = 0.38 ENDF-B.VII F = 0.36 JENDL/4.0 EAF/KADoNiS=2.28 ENDF/KADoNiS=2.51 C/E(Ires ) = 0.69 EAF C/E(Ires ) = 0.60 ENDF The normalization factor ???

29. Performance of calculationsMACS(cal) vs MACS(exp) Bao 2000 NON-SMOKER TALYS

30. EAF-2010

31. Uncertainties of statistical componentEnergy region EV – 8 MeV C/E values for EAF integral s(30 keV) against KADoNiS value <I(30 keV)> gives a sensitive check of the cross section fit just bellow EV and EH and of the statistical component above EH up to 1 MeV. We define • f(EH - 20 MeV) – 1 = SQRT ((1 - C/E(I30))2 + DI302)), with C/E(I30) representing the fit of EAF data with the recommended KADoNiS value and DI<30 keV> is the associated relative experimental error of KADoNiS

32. Conclusions • Integral experiments proved to be a very valuable validation tool, however, the need for broader neutron spectra to address the high energy components of excitation curves is recognized • 30 keV cross sections Observations: 1. Small sensitivity to maximum of the neutron spectrum with kT around 30 keV 2. KADoNiS can be used both as differential or integral data with about 10% uncertainty 3. (p,Li-6) - reaction data are the most reliable experimental information, no correction for capture needed

33. Conclusions 4. Both values (point-wise value as well as integral average), are an excellent tool to validate and/or improve the accuracy of the statistical component of the capture cross section. This can be especially applied for reactions with no resonance data and using the simplified modelling of combination of 1/v and statistical components, with EV=EH as a free parameter 5. Another possible application is the test of resolved resonance representation in MT102 in combination with resonance integral data for 1 keV < EV < 500 keV range

34. Conclusions 6. The comparison with NON-SMOKER predictions opens a possibility to use EAF-2010 and such future data for astrophysics applications 7. C/E of MB average cross section can be used to quantify the uncertainty factor of the dstatistical component above EH 8. A paper is in preparation describing this work