1. Precise neutron inelastic cross section measurements A.Negret 1 1 “Horia Hulubei” National Institute for Physics and Nuclear Engineering, Bucharest, ROMANIA Carpathian Summer School of Physics 2012, Sinaia

2. A. Negret - Neutron inelastic cross section measurements Summary Introduction Experimental setup & Analysis Results for 28 Si(n,n’  ) 28 Si Comparison with 25 Mg( ,n  ) 28 Si Conclusion Carpathian Summer School of Physics 2012, Sinaia

3. Introduction Experimental setup & Analysis Results for 28 Si(n,n’  ) 28 Si Comparison with 25 Mg( ,n  ) 28 Si Conclusion Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

4. Neutron data Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

5. NEA High priority list 28 Si – Gas Cooled Fast Reactors (GFT) 56 Fe, 206,207,208 Pb – structural materials Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

6. (N,Z)  n What do we measure v n (N,Z) Elastic scattering Inelastic scattering Nuclear reactions Fission (N 2,Z 2 ) (N 1,Z 1 ) n n Cross section (  ) n (N,Z) (N+1,Z-1) p Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

7. Neutron inelastic scattering Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

8. Experimental setup & Analysis Introduction Experimental setup & Analysis Results for 28 Si(n,n’  ) 28 Si Comparison with 25 Mg( ,n  ) 28 Si Conclusion Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

9. Overview of the experimental procedure Neutron source 200 m flight path FP3/200 cabin; GAINS + FC Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

10. GELINA neutron source Electron linac (150 MeV) + 238 U target Pulse width ~1 ns Repetition rate: 800 Hz Energy range: 0 – 20 MeV Gamma flash from bremsstrahlung Flight path: 200m (~550 neutrons/cm 2 s) Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

11. GAINS 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 Inelasic Neutron Scattering Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

12. Experimental problems The gamma flash Time resolution Long time measurements Distance from the neutron source : FP = 200m Small neutron flux Stability of the electronics Simplification of the acquisition system The digitizer-based acquisition Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

13. Overview of the data analysis 8 x HPGE yieldFC yield Efficiency: Monte-Carlo simulation Multiple scattering correction: Monte-Carlo simulation Gamma Production cross sections NDS: level scheme Total inelastic cross section Level cross sections Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

14. Results Introduction Experimental setup & Analysis Results for 28 Si(n,n’  ) 28 Si Comparison with 25 Mg( ,n  ) 28 Si Conclusion Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

15. What did we see? 28 Si + n 29 Si Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

16. Gamma production cross sections in 28 Si Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

17. Total inelastic cross section Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

18. Level production cross sections Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

19. Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements Comparison with 25 Mg( ,n  ) 28 Si Introduction Experimental setup & Analysis Results for 28 Si(n,n’  ) 28 Si Comparison with 25 Mg( ,n  ) 28 Si Conclusion

20. Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements 28 Si + n 29 Si 28 Si(n,n’  ) 28 Si vs 25 Mg( ,n  ) 28 Si 25 Mg +  25 Mg( ,n  ) 28 Si measurement performed at the Tandem accelerator of IFIN-HH, Bucharest: The same Compound nucleus, 29 Si The same exit channel We measured the production cross sections for the same gamma rays:

21. Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements 28 Si(n,n’  ) 28 Si vs 25 Mg( ,n  ) 28 Si

22. Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements 28 Si(n,n’  ) 28 Si vs 25 Mg( ,n  ) 28 Si

23. Conclusions Introduction Experimental setup & Analysis Results for 28 Si(n,n’  ) 28 Si Comparison with 25 Mg( ,n  ) 28 Si Conclusion Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

24. Conclusions The GAINS spectrometer installed at the neutron source GELINA represents a powerful tool for producing neutron inelastic cross sections On-going experiments and analysis for many data sets: 206 Pb, nat Fe, 28 Si, 24 Mg, 23 Na, 12 C, 90 Zr, 57 Fe, nat Cu. Current attempts aim to the development of alternative methods to the direct measurement of neutron-induced cross sections. Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements

25. Advertisement Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements The ERINDA consortium groups 13 partners, equipped with nuclear data research infrastructures. The project sponsors the transnational access for experiments performed at any of the 13 facilities. The TANDEM accelerator of IFIN-HH is part of ERINDA. The next (and last) deadline for proposals: September 30, 2012 www.erinda.org

26. Thank you! Carpathian Summer School of Physics 2012, Sinaia A. Negret - Neutron inelastic cross section measurements