1. Anti-neutrinos Spectra from Nuclear Reactors Alejandro Sonzogni National Nuclear Data Center

2. Anti-neutrinos #2 - Alejandro Sonzogni ENDF/B VII.1 Decay Data Sub-Library Most recent … Q values -- Audi 2011 mass update ENSDF data (when complete) else Wallet Cards (2011) Atomic data -- Evaluated Atomic Data Library (LLNL) – includes X-rays and Auger electrons TAGS data Electron conversion -- BrIcc Theoretical calculations for neutron-rich nuclei using beta-strength functions (Moller) and CGM (Kawano) More details in Nuclear Data Sheets 112, 2887 (2011).

3. ENDF VII.I Decay Data Sub Library A transformation of all relevant data into computer “friendly” files

4. What’s in there… Wallet Cards Theory (CGM) ENSDF New ENSDF 3817 “materials” g.s. and isomers

5. What’s it good for … Decay heat Antineutrino spectra Delayed nu-bars (reactor operation) Astrophysics ? ????

6. Antineutrino Experiments

7. Decay of fission fragments More than 800 nuclides produced in the fission of 235 U Antineutrino Spectrum: S (E) =  Y i x S i (E) Y i : cumulative fission yields S i (E): individual  spectrum

8. Anti-neutrinos #8 - Alejandro Sonzogni JiiJii Z,N Nucleus JkkJkk EkEk IkIk Z+1,N-1Nucleus  - decay from Level i to level k a: normalization, d: shape factor, F: Fermi function. The sum spectrum is obtained as: b: branching ratios All nuclear decay data from ENDF/B-VII.1 (December 2011)

9. Anti-neutrinos #9 - Alejandro Sonzogni Example, 137Cs

10. Anti-neutrinos #10 - Alejandro Sonzogni How to calculate anti-neutrino rates -- -- (n,  ) The nuclei in the core form a decay/processing network: Neglect processing as  n  << and consider an equilibrium situation: Then the anti-neutrino rate per fission is: Used by Vogel et al, 1981, ENDF/B-V We’ll repeat the calculations using the fission yields from ENDF/B-VII.1

11. Anti-neutrinos #11 - Alejandro Sonzogni 235 U at thermal energies

12. Detection through inverse  decay on proton Anti-neutrinos from reactors Reaction threshold : ~1.8 MeV Flux Principal Contributors 235 U, 238 U, 239 Pu, 241 Pu

13. Anti-neutrinos #13 - Alejandro Sonzogni NNDC calculations on the Daya signal shape

14. Anti-neutrinos #14 - Alejandro Sonzogni Nucleus% at 3 MeV 54-Xe-1373.519 55-Cs-1393.259 39-Y - 943.120 40-Zr- 993.010 41-Nb-1002.916 41-Nb- 982.830 39-Y - 922.812 41-Nb-1012.654 Nucleus% at 4 MeV 41-Nb-1004.872 37-Rb- 923.694 39-Y - 963.545 52-Te-1352.994 39-Y - 942.897 55-CS-1402.780 39-Y - 952.646 54-Xe-1392.606 Nucleus% at 5 MeV 37-Rb- 929.171 39-Y - 967.475 41-Nb-1006.592 55-Cs-1424.585 55-Cs-1404.153 52-Te-1353.636 39-Y - 993.460 38-Sr- 953.435 With TAGS: 140Cs. 96Y seems is good shape. We’ll look at some of the other nuclides and if available, compare it to Rudstam data. 235 U(thermal n,f) main contributors to anti- neutrino spectra

15. 51(18) % a) 2000 ENSDF 95(5) % b) Update with new data g.s. One small nucleus, one big effect 92 Rb

16. Anti-neutrinos #16 - Alejandro Sonzogni Effects of Valencia TAGS data

17. Anti-neutrinos #17 - Alejandro Sonzogni Anti-neutrinos for Applied Purposes 235,238 U and 239 Pu produce a different signal, in shape, maxima and multiplicity

18. Anti-neutrinos #18 - Alejandro Sonzogni 100 Nb, CFY=5.89E-2,  CFY=16.883 % The GS to GS transition is not well determined. It could be up to 75%. BNL plans to submit a proposal to CARIBU. Would include other Nb nuclides

19. Anti-neutrinos #19 - Alejandro Sonzogni 142 Cs, CFY=2.71E-2,  CFY=2.803 %

20. Anti-neutrinos #20 - Alejandro Sonzogni 92 Rb, CFY=4.82E-2,  CFY=1.398 %

21. Anti-neutrinos #21 - Alejandro Sonzogni 92 Rb, comparison to Rudstam data

22. Anti-neutrinos #22 - Alejandro Sonzogni 92 Rb, comparison to Rudstam data

23. Anti-neutrinos #23 - Alejandro Sonzogni Summary The next generation of experiments using anti-neutrinos from nuclear reactors have just published their first results. More to come in the next few years. There is a close link between basic nuclear structure research and the calculation of anti-neutrino spectra.

24. Anti-neutrinos #24 - Alejandro Sonzogni Why nuclear reactors? Nearly 1,000 different fission fragments (materials) are produced in the fission of an actinide nuclide. Most of them are neutron rich, undergoing beta- minus decay: Nucleus(Z,A)  Nucleus(Z+1,A) + e- + anti-neutrino In an equilibrium situation, we obtain about 6 anti- neutrinos/second per fission, or ~10 20 anti-neutrinos per reactor. Anti-neutrinos interact through weak interaction, very small cross sections,  ~ 5x10 -19 barns

25. Anti-neutrinos #25 - Alejandro Sonzogni Some history In  - decay, the electron energy is a continuum distribution linking two nuclear levels (quantum). Another particle must be involved n  p + e- + anti-neutrino (Fermi, 1934) First detection in 1956 by Cowan and Reines (LANL) using neutrinos from a nuclear reactor in SRS: anti-neutrino + p  n +e+ The positron created two 511 keV gammas and the neutron was captured in Cd, releasing a gamma cascade

26. Anti-neutrinos #26 - Alejandro Sonzogni More history In 1962, Leon Lederman and collaborators (BNL) discovered the muon neutrinos: Finally, in 1975 the Tau lepton and in 2000 the Tau neutrino were discovered. In the late 1960’s Ray Davies (BNL) measured the flux of neutrinos coming from the Sun, observing a deficit. Neutrino oscillations were formalized to explain this problem.

27. Anti-neutrinos #27 - Alejandro Sonzogni 239 Pu at thermal energies

28. Anti-neutrinos #28 - Alejandro Sonzogni 238 U at fast energies

29. Anti-neutrinos #29 - Alejandro Sonzogni 252 Cf spontaneous fission

30. Anti-neutrinos #30 - Alejandro Sonzogni 235 U  - spectra ratios The published ILL data is binned at 250 keV. Could we get the 50 keV data?

31. Anti-neutrinos #31 - Alejandro Sonzogni 239 Pu  - spectra ratios

32. Anti-neutrinos #32 - Alejandro Sonzogni 238 U  - spectra ratios

33. Anti-neutrinos #33 - Alejandro Sonzogni 252 Cf  - spectra ratios More theory needed, but better agreement with higher statistics, cleaner data

34. Anti-neutrinos #34 - Alejandro Sonzogni anti-neutrino + proton (water) positron + neutron Two 511 keV gammas Captured in Gd High energy gamma signal 3 near neutrino detectors and 3 far neutrino detectors

35. Anti-neutrinos #35 - Alejandro Sonzogni Anti-neutrino Signal Use the anti-neutrino capture on proton: Reaction has a 1.8 MeV threshold

36. Anti-neutrinos #36 - Alejandro Sonzogni Daya Bay Results

37. Anti-neutrinos #37 - Alejandro Sonzogni Some recent experiments Daya Bay Experiment in China, 6 nuclear power reactors. Ref: F.P. An et al, Physical Rev. Lett. 108, 171803 (2012)