1. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006 Fission cross section measurements with a coincidence method Measured isotopes : 233 U, 234 U, 232 Th, 237 Np, and 209 Bi, nat Pb References : 235 U and 238 U Focus on isotopes with several targets : 234 U (2 targets), 232 Th (5 targets), 237 Np (4 targets)

2. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006 Detection layout

3. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006 Solid angle acceptance 237 Np : 10 MeV < En < 15 MeV (2 targets) Target 1 Target 2

4. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006  f for 234 U

5. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006 238 U/ 235 U ratio

6. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006  f for 237 Np

7. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006 Corrected counting rate of 237 Np targets

8. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006 Raw counting rate of 237 Np targets

9. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006 Raw counting rate of 232 Th targets

10. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006  f for 237 Np (raw)

11. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006  f for 232 Th (raw)

12. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006 238 U/ 235 U ratio (raw)

13. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006 Conclusion The efficiency at 0° is lower than 1 when all localisation signals are requested (unexpected) The cross section based on anode signals is more reliable, and a good reproducibility is obtained for different targets Not protected against variations of angular distribution (between 0.5 MeV and 50 MeV), and need of a normalisation factor. A cross section accuracy better than 10% can probably be achieved

14. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006 Selection of fission Singles Coincidence

15. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006 Use of FADCs : pile up resolution Original signals - anode (black) - cathode right (red) - cathode left (green) Signals after filtered derivative (convolution) 50 channels 500Ms/s

16. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006 Use of FADCs : noise reduction Original signals Signals after filtered derivative (convolution)

17. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006 Energy resolution 235 U around 10eV ( scaled and compared to ENDF) 234 U around 570eV

18. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006 Targets 237 Np, 233 U, 234 U, 232 Th, 209 Bi, nat Pb Thin layer (0.3mg/cm 2 ) of 8cm in diameter Electrodeposition on Al backing (2  m thick) 234 U Measured isotopes Reference isotopes : 235 U, 238 U

19. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006 fission α activity 234 U 209 Bi nat Pb Targets with Ø=8cm Extended targets Emitting point distribution on the target

20. L. Tassan-Got Fission cross section measurements with coincidences CB n-TOF 5/12/2006 Flux from 235 U and 238 U (JENDL above 20 MeV)