CIELO O-16
Date: 6 February 2014
Place: Phone conference
Time: 16:00 (Paris, GMT+1), 8:00 (Los Alamos, GMT-7), midnight (Tokyo, GMT+9)
Participants:
IRMM: A.Plompen
JAEA: S.Kunieda
KAPL: C.Lubitz
LANL: G.Hale
IAEA: S.Simakov
NEA: E.Dupont
The objective of this phone conference is to share progress and plans on the 16O evaluation for the
CIELO pilot project. A short-term milestone is to have a starter file by May 2014. For 16O, leading
actors are in the US, Europe and Japan with very different time zones. Hence, it was planned to split thediscussions. This first phone conference was scheduled during working hours in US and Europe andmainly focused on experimental data. A second phone conference will be scheduled during working
hours in US and Japan in order to further discuss data modelling.
A.Plompen summarized the experimental information available for the 17O system (see NEMEA/CIELO
presentations1). At low energy (up to a few keV), the status of the neutron scattering and total crosssection data was reviewed by S.Kopecky and the NEMEA/CIELO paper is being prepared. As noted byC.Lubitz during the workshop, the SiO2 measurements should be corrected using the latest Si data. At
higher energy, additional data are available for the (n,a) and (a,n) channels. G.Giorginis (now retired)recently proposed an update to the “drift velocity” correction that must be applied to the (n,a) crosssection measured at IRMM. Above En ~6 MeV, the latest corrected data are now consistent with the one
measured by V.Khryachkov at IPPE. After the meeting, G.Giorginis showed how the agreement among
IRMM, IPPE and Bair & Haas data at ~6.4 MeV may influence the re-normalisation below 6 MeV.
However, there is still a disagreement with the (a,n) data measured by Harissopulos that has to beclarified.
G.Hale said that this is very encouraging because the new IRMM correction is going in the right
direction to derive a set of resonance parameters consistent with experimental information from the (n,a)
and (a,n) channels, and from the total cross section. In addition, the other corrections discussed earlier(e.g. taking into account the amount of H(2O) in the Ohkubo and Johnson samples) are also going in theright direction and do not affect the unitary consistency as confirmed by S.kunieda. The R-Matrix
analysis should now be repeated after having done all required corrections.
A.Plompen noted the review performed by S.Simakov and illustrated in the plots given below. It showsthat the (a,n) data measured by Bair & Haas should be re-normalised, but also that there is another issue
in the energy scale that should be clarified (see the last plot with alpha energies between 2.5 MeV and2.9 MeV). S.Simakov commented that one can see a shift in the peak positions of different data sets, aswell as differences in peak amplitudes. He added that in the case of Bair & Haas and Harissopulos data
the quoted energy was the effective energy of the alpha particle at the center of the target. He also asked
if evaluators consider small shifts of resonances during fitting procedure why then the ENSDF
resonances, which are adopted from many reactions, cannot be used as reference values. A.Plompen
noted that corrections for target thickness effects are difficult and that a full analysis should be done.

1www.oecd-nea.org/science/wpec/nemea7/presentations.html

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C.Lubitz suggested using the total cross section measured by Cierjacks as a reference for the energy
scale. G.Hale commented that level energies are obviously the same for all reaction channels but this is
not necessarily true for the peak positions, which may be shifted. It was agreed to use the R-Matrix
theory to estimate the energy shift that one may reasonably expect between the (n,a) and the total crosssections.
E.Dupont inquired about the situation at higher energy (beyond En ~6 MeV). G.Hale commented that thenew IRMM data are now more consistent with ENDF/B-VI.8 as compared to ENDF/B-VII, which wasadjusted on preliminary results. A.Plompen noted that the R-Matrix analysis will be difficult as soon asadditional channel becomes significant. G.Hale said that he has done the analysis up to 7 MeV but
agreed that the “resonance region” should stop at the opening of the (n,a1) channel, i.e. En ~5.6 MeV. Of
course, the “resonance region” will be complemented with MF3 data at higher energy (up to 150 MeVin ENDF/B-VII.1).
C.Lubitz noted that there is no resonance parameter in the ENDF/B-VII.1 evaluation and recommended
to provide those parameters in the CIELO evaluation. He would also be interested to have access to theresonance parameters associated to the ENDF/B-VII.1 evaluation in order to test the integral
performances of slight (consistent) adjustments in the low energy cross sections. Actually, theavailability of resonance parameters was the main reason for using the SAYER 2000 evaluation forthese integral tests and similar tests using ENDF/B-VII.1 data would be useful.
G.Hale answered that the EDA code uses relativistic kinematics to adjust the resonance parameters andthis formalism is not available in the ENDF format. C.Lubitz thinks that feeding G.Hale’s File 3 totaland elastic and maybe (n,a) to SAMMY as experimental data with small uncertainties and cut off at
6.2 MeV would produce a non-relativistic fit good enough for what he needs. SAMMY would only needapproximate non-relativistic resonance energies and widths as starting values.
A.Plompen mentioned that L.Leal is updating the SAYER 2000 evaluation using recent experimental
data (see NEMEA/CIELO presentation). The simultaneous fit gives good result but no information wasprovided on the adjusted normalisations. G.Hale had concerns about possible unitary issues.
Adjourn2

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