Institute for Reference Materials and Measurements (IRMM) Geel, Belgium CRP Th - U, Vienna December 2004 Evaluation of the 232 Th Resonance Parameters in the RRR and URR A. Brusegan †, F. Corvi, P. Schillebeeckx, P. Siegler, K. Volev, EC-JRC-IRMM, B-2440 Geel, Belgium N. Koyumdjieva, N. Janeva, A. Lukyanov INRNE, Sofia, Bulgaria L. Leal ORNL, Oak Ridge, USA M.C. Moxon Hyde Copse, Marcham, United Kingdom

CRP Th - U, Vienna December 2004 Th - U Cycle 232 Th(n,tot) and (n,  ) collaboration withINRNE Sofia (BG) CEA Saclay (F) M. Moxon & L. Leal 234 U(n,f) & 236 Th(n,f) collaboration withGhent University (B) 233 Pa(n,f) & 231 Pa(n,f) collaboration withUniv. Örebro and Uppsala (S) Bucharest University (RO)

CRP Th - U, Vienna December 2004 Thorium Produce resonance parameters in RRR & URR Old capture data suffer from systematic uncertainty due to normalisation and weighting function Simultaneous analysis of new capture data and transmission data: –GELINA (capture + transmission + Doppler) –ORELA (transmission) –n – TOF (capture) Unified description of RRR and URR URR ( keV) (submitted Nucl. Sci. Eng.)

CRP Th - U, Vienna December Th(n,tot) and (n,  ) RRR & URR URR Statistical Models Res. Par. E oj,  n,j,  ,j, J j, R High Energy Optical Models Thermal RRR R-Matrix Level Statistics D 0, S o, Average Par. D o,1, S o,1,, R

CRP Th - U, Vienna December 2004 Improved Normalisation Procedure N = 6.92 (0.02)N = 7.16 (0.03) 3.5 % difference, Influence of sample thickness (ND2004, Borella et al.) Similar problem for n – TOF data with 1 mm sample in URR Neutron Energy / eV 59.0 Capture Yield n c = at/b

CRP Th - U, Vienna December 2004 Unresolved Resonance Region Study of Systematic Effects

CRP Th - U, Vienna December 2004 Evaluation with FITACS Internal Normalisation

CRP Th - U, Vienna December 2004 Result of the Evaluation Total Capture

CRP Th - U, Vienna December 2004 Result of Evaluation

CRP Th - U, Vienna December 2004 Matching RRR & URR

CRP Th - U, Vienna December Th(n,tot) and (n,  ) in RRR Resonance parameters  (E 0,  n,  , g) for  n <   transmission and capture are not complementary since:

CRP Th - U, Vienna December Th Resolved Resonance Region Simultaneous analysis of transmission and capture DetermineR’ Determine   Determine  n Verifyg  Examples

CRP Th - U, Vienna December 2004 Scattering Radius from Transmission Measurements With Thick Sample R’ = 8.9 fm R’ = 9.5 fm from URR ! Neutron Energy / eV Transmission

CRP Th - U, Vienna December 2004 Spin & Parity Assignment Mainly based on statistical analysis Parity of some resonances verified by Corvi based on gamma cascade

CRP Th - U, Vienna December 2004 Statistical factor from Simultaneous Analysis of Capture and Transmission Data Neutron Energy / eV Capture Yield Transmission g = 2g = 1

CRP Th - U, Vienna December 2004 Radiation Width from Simultaneous Analysis of Capture and Transmission  n = 8.76 meV   = meV parameters only from data of Olsen et al.  n = meV   = meV simultaneous analysis capture + transmission Neutron Energy / eV Transmission Capture Yield

CRP Th - U, Vienna December 2004 Average Radiation Width from Capture data REFIT RRR ORELA (Transmission) : = 25.1 (0.4) meV IRMM (Capture) : = (0.06) meV URR = 24.0 (0.4) meV

CRP Th - U, Vienna December 2004 Fission Cross Sections 234 U(n,f) at GELINA & ILL (Thermal) 236 U(n,f) at GELINA & ILL (Thermal) 233 Pa at VdG 231 Pa at VDG

CRP Th - U, Vienna December 2004 The fast-neutron induced fission cross-section of 233 Pa The present result is lower than all previous evaluations and experiments. Model independent. Reasonable agreement with JENDL-3.3 below second- chance fission. Cross section values extracted from fission probability data are model dependent. They are in reasonable agreement with the present result, but seem to overestimate the cross section.  n,f = P f ·  cn 232 Th( 3 He,pf) 234 Pa Model calculation

CRP Th - U, Vienna December 2004 The fast-neutron induced fission cross-section of 233 Pa Present calculation

CRP Th - U, Vienna December Pa fission cross section

CRP Th - U, Vienna December Pa(n,f) calculation compared to scaled experimental data

CRP Th - U, Vienna December Pa(n,f) at VdG Measurements from 0.5 to 3.5 MeV at VdG Preliminary cross section shape agrees with other available data sets, but absolute value about 10% lower then data from Plattard et al. and in better agreement to the surrogate data from Petit et al. Measurements from 15 to 21 MeV at VdG accelerator Preliminary cross sections much lower then data from Plattard et al. and in good agreement to the only point from Birgul et al at 14.8 MeV. 231 Pa fission cross section calculations performed based on the measurements below 4 MeV In agreement with the shape of available experimental data, but lower due to the fact that the VdG data are lower by 10%. At the higher fission chances, the calculation follows more to the surrogate data of Petit et al. The new experimental data above 15 MeV do not fit yet in the calculations.

CRP Th - U, Vienna December U & 236 U n th 1eV – 150 keV 234 U(n,f) Published Nucl.Sci.Eng. 141, 171 (2002) To be published 236 U(n,f) Published Nucl.Sci.Eng. 136, 415 (2000) Ongoing

CRP Th - U, Vienna December 2004 Resonance at 5.16 eV 234 U(n,f)