1. Neutron inelastic scattering measurements at the GELINA facility of EC-JRC-IRMM A. Negret 1, C. Borcea 1, A. Plompen 2 1 NIPNE-HH, Romania 2 EC-JRC-IRMM, Belgium

2. A. Negret - Neutron inelastic scattering measurements at GELINA Summary Introduction Experimental setup Experimental results: 56 Fe(n,n’  ) Data analysis Conclusions

3. A. Negret - Neutron inelastic scattering measurements at GELINA Summary Introduction Experimental setup Experimental results: 56 Fe(n,n’  ) Data analysis Conclusions

4. A. Negret - Neutron inelastic scattering measurements at GELINAIntroduction HH-NIPNE, Romania & EC-JRC-IRMM, Belgium

5. A. Negret - Neutron inelastic scattering measurements at GELINAIntroduction What do we measure v n (N,Z) n n  (N+1,Z-1) p (N 2,Z 2 ) (N 1,Z 1 ) n n Elastic scattering Inelastic scattering Nuclear reactions Fission Cross section (  )

6. A. Negret - Neutron inelastic scattering measurements at GELINAIntroduction Neutron inelastic scattering Gamma production cross section Level cross section Total cross section

7. A. Negret - Neutron inelastic scattering measurements at GELINAIntroduction Why do we measure inelastic cross sections

8. A. Negret - Neutron inelastic scattering measurements at GELINAIntroduction Sensitivity studies

9. How do we measure A. Negret - Neutron inelastic scattering measurements at GELINAIntroduction A(n, n’  ) A(n, 2n  ) Primary experimental result: Gamma production cross section Databases: Level scheme Level cross section Total inelastic cross section Uncertainty ~5% for the strongest transitions

10. Summary Introduction Experimental setup Experimental results: 56 Fe(n,n’  ) Data analysis Conclusions A. Negret - Neutron inelastic scattering measurements at GELINA

11. Experimental setup Electron linac (150 MeV) + 238 U target Pulse width ~1 ns Repetition rate: 800 Hz Energy range: 0 – 25 MeV Gamma flash from bremsstrahlung Flight path: 200m (~20 neutrons/burst) Neutron source: GEel LINear Accelerator (GELINA)

12. A. Negret - Neutron inelastic scattering measurements at GELINAExperimental setup 8 HPGe detectors @ 110° & 150° (Accurate integration of angular distribution up to the sixth order of Legendre polynomials) TOF technique: Amplitude  gamma energy Time  neutron energy Digitizer-based acquisition (Acqiris DC440, 420 MS/s, 12 bits) Beam monitoring: 235 U Fission chamber Gamma Array for Inelastic Neutron Scattering (GAINS)

13. Acquisition Electronics A. Negret - Neutron inelastic scattering measurements at GELINAExperimental setup DC440 Acqiris digitizers: 420 MS/s (2.38 ns/sample) 12 bits (4096 amplitude channels)

14. Summary Introduction Experimental setup Experimental results: 56 Fe(n,n’  ) Data analysis Conclusions A. Negret - Neutron inelastic scattering measurements at GELINA

15. Results: 56 Fe(n,n’  ) 56 Fe(n,n’  ) Sample: nat Fe ( 56 Fe / nat Fe = 91.75%) Thickness: 3mm, 1mm, 4mm Purity 99.5% Beam time: 3 mm sample: 6 weeks 4 mm sample: 3 weeks 1 mm sample: 2 weeks additional checks: 5 weeks

16. A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56 Fe(n,n’  ) 56 Fe(n,n’  ): gamma spectrum

17. A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56 Fe(n,n’  ) 846.8 keV gamma production cross section

18. A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56 Fe(n,n’  ) 1238.3 keV gamma production cross section

19. A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56 Fe(n,n’  ) 1810.8 keV gamma production cross section

20. 846.8 keV level cross section A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56 Fe(n,n’  )

21. A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56 Fe(n,n’  ) 2085.1 keV level cross section

22. A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56 Fe(n,n’  ) Total inelastic level cross section

23. A. Negret - Neutron inelastic scattering measurements at GELINA Summary Introduction Experimental setup Experimental results: 56 Fe(n,n’  ) Data analysis Conclusions

24. A. Negret - Neutron inelastic scattering measurements at GELINAData analysis Sensible points of the analysis: background of the 846.8 keV transition The strongest gamma transition (846.8 keV) may overlap with: 72 Ge(n,n’  ): 834 keV + Ge recoil energy 27 Al(n,n’  ): 844 keV

25. A. Negret - Neutron inelastic scattering measurements at GELINAData analysis 206 Pb(n,n’  ) check

26. A. Negret - Neutron inelastic scattering measurements at GELINAData analysis 56 Fe(n,n’  ) with various sample thicknesses

27. A. Negret - Neutron inelastic scattering measurements at GELINA Summary Introduction Experimental setup Experimental results: 56 Fe(n,n’  ) Data analysis Conclusions

28. A. Negret - Neutron inelastic scattering measurements at GELINAConclusions We measured 56 Fe(n,n’  ) cross sections using the GELINA neutron source and the GAINS gamma spectrometer of EC- JRC-IRMM: gamma production cross sections level cross sections total inelastic cross section Very detailed consistency checks were performed to make sure that the data are reliable. Significant differences from the previous measurements persist and remain unexplained.