Reactor Electron Neutrino Magnetic Moment and Radiative Decay Studies

1. STUDIES OF REACTOR ELECTRON NEUTRINO MAGNETIC MOMENT AND RADIATIVE DECAY • M-C simulation of reactor e flux; • Data analysis for the limits of electron neutrino magnetic moment ; • Data analysis for the limit of neutrino radiative decay lifetime; • Some physics potential of reactor neutrino experiment. XIN Biao / 辛 標 On behalf of TEXONO collaborator China Instituteof Atomic Energy/中國原子能科學研究院 2004.02 @新竹

2. M-C simulation of reactor e flux Theory calculation Magnetic moment M-C simulation Magnetic moment Experiment Measurement Radiative decay Experiment Measurement Radiative decay Reactor

3. Physical model Geometry description Neutron sampling Probability of EC decay Electron neutrino emission Electron neutrino flux Simulation of reactor electron neutrino flux Nuclear material Fission products Structure material n n rich nuclei －decay EC EC n rich nuclei － decay Stable isotope even-even Stable isotope electron anti-neutrino emission

4. M－C simulation ——source of reactor electron neutrino 104Pd stable － EC 103Rh stable 104Rh 42s n Direct fission product 103Ru 39d 104Ru stable Z 103Tc 50s 104Tc 18m QEC(MeV) PEC(%) Y(Z, N) (Per fission) Y(Z, N)×PEC (Per fission) N 235U 239Pu 235U 239Pu －decay of fission product 86Rb 0.53 0.005 1.4E-5 - 7E-10 - 87Sr 0.2 0.3 <1E-5 - <3E-8 - 104Rh 1.15 0.4 7E-8 - 3E-10 - 108Ag 1.9 1.7 - - - 1E-9 110Ag 0.88 0.3 - 1.3E-5 - 4E-8 Direct fission product 128I 1.26 6.0 1.2E-8 1.7E-6 7E-10 1E-7 Fission products Structure material

5. M－C simulation ——source of reactor electron neutrino Neutron activation fission products

6. isotopes Decay lifetime T1/2 enrichment of the nucleus (A-1 ) QEC (MeV) PEC(%) M－C simulation ——source of reactor electron neutrino 55Fe 2.7y 5.8 0.23 100 51Cr 27.7d 4.3 0.75 100 59Ni 7.6*104y 68.1 1.073 43 113Sn 115.09d 0.97 1.036 49 Structure material Contribution to electron neutrino ?

7. Total flux of electron neutrino emitted from reactor structure material： Contribution of different isotopes： Ratio of neutron capture probability of each isotope in the different cell： M-C simulation of reactor electron neutrino ——physical model 50Cr, 54Fe, 58Ni, 112Sn • 51Cr + e-51V + νe • 55Fe + e-55Mn + νe • 59Ni + e-59Co + νe • 113Sn + e-113In + νe activation isotopes in reactor structure material

8. M-C simulation of reactor electron neutrino ——geometry description • 50Cr in RC , SS & Zr-alloy; • 54Fe in RC , SS & Zr-alloy; • 58Ni in RC , SS& Zr-alloy; • 112Sn inZr-alloy; • Nuclear fuel material: UO2; • enrichment of 235U :3 %; • Height of the fuel rod:400cm; • Radius of the fuel rod: 0.45cm;

9. M-C simulation of reactor electron neutrino ——geometry description Reactor core: 624 lattices; Fuel rod: 72 rods in each lattice; Mass of UO2: 138 tons; Control rods And water Zr-alloy UO2

10. M-C simulation of reactor electron neutrino ——geometry description RC 4967tons、stainless steel 1040tons、Zr-alloy 63 tons • 50Cr --0.95%; • 54Fe --4.2%; • 58Ni --6.3%; • 112Sn --0%. • 50Cr --0.01%; • 54Fe --0.1%; • 58Ni --0.63%; • 112Sn --0%. • 50Cr --0.005%; • 54Fe –0.006%; • 58Ni --0.34%; • 112Sn –0.01%.

11. M-C simulation of reactor electron neutrino ——neutron transport • Source neutron sampling Watt fission spectrum ： Fired by thermal neutron : a＝0.988 b＝2.249 • Simulation of neutron flux • Tallies

12. Simulation result Fission neutrons are mostly absorbed by fuel rods and control rods; Electron neutrino are mainly contributed by Cr-50 in control rods;

13. Simulation result 94% of the captured neutrons are thermal neutrons. n-absorption: Thermal neutron capture cross-section

14. Simulation result Neutrino flux at detector position due to Cr-50 is: 5.0×108 cm-2s-1 Cross check—— K-eff calculation; • Uncertainty: • The SD of M-C simulation <0.1%; • System error < 15%;

15. Data analysis for reactor electron neutrino magnetic moment Scattering • Electron recoil spectrum • emagnetic moment fitting

16. Data analysis——magnetic moment Reactor on A0 Reactor on a) t0 t1 t2 t3 t4 Reactor on Aon Reactor on Reactor off b) Aoff Flux Time • Nsm(E)和Nmm(E) Average flux t0： 2001年9月8日； t1： 2001年10月8日； t2： 2001年11月14日； t3： 2001年12月18日； t4： 2002年1月15日；

17. Data analysis----neutrino magnetic moment • Nsm(E) and Nmm(E) Flux of e： flux： 5.0×108cm-2s-1 Energy ： 747keV detector： material：HPGe Mass ：1.054kg

18. date.rz Data analysis——program Spectrum adding ΣNi(E) Standard cut (PSD, cosmic-veto, anticompton) Read the real measurement time Ti Energy calibration Dead time correction (ai)、random correction (bi, ci) Single spectrum Ni(E) Next spectrum？ No Spectrum normalization n(E)=ΣNi(E)/ ΣTiai bici Yes Read the next *.rz file The end

19. Data analysis ——spectrum processing Normalized Non(E) and Nbkg(E) Non(E)－Nbkg(E)

20. Data analysis——fitting of the e

21. Data analysis——neutrino decay • Decay model • Decay lifetime (c.m./m) • Fitting of the experiment data

22. Data analysis ——neutrino decay Energy range：0～6MeV

23. Data analysis——neutrino decay Non(E)－Nbkg(E)

24. Data analysis——neutrino decay h＝－0.055±0.061 t/mn≥1.3 s·eV－1(C.L. 68%)

25. Physics potential Can we increase the flux of the electron neutrinos emitted from a reactor ? 1 fuel rod replaced by Cr-50 rods, …… 2 fuel rods replaced by Cr-50 rods … n fuel rods replaced by Cr-50 rods …

26. Physics potential The reactor still work well Neutrino flux can be enhanced up to 103times

27. Physics potential 71Ga(ne, e－)71Ge CC event rate • Neutrino flux: 2×1011cm-2s-1 ; • 10 tons target materials in nature;

28. Conclusion • We performed the simulation of the emissions of electron neutrinos from a nuclear reactor. At detector position, the electron neutrino flux due to 51Cr is : 5.0×108cm2s-1； • The limits of electron neutrino magnetic moment and radiative decay lifetime has been found based on a reactor neutrino experiment： • The physics potential of the reactor neutrino experiment has been discussed. t/mn≥1.3 s·eV－1(C.L. 68%)

29. Thanks !