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Production of Electron Neutrinos from Reactor and the Physics Potentials

This study explores electron neutrino production from reactors, with emphasis on M-C simulations and data analysis. It investigates physics potentials regarding neutrino magnetic moments and radiative decay lifetimes. The research involves detailed modeling of reactor structures, fission products, and isotopes. The simulation results show contributions from specific isotopes like Cr-50 in control rods. Potential enhancements in neutrino flux are suggested by replacing fuel rods with Cr-50 rods, highlighting implications for reactor performance. Data analysis focuses on electron neutrino magnetic moment fitting and neutrino decay modeling, with applications in neutrino event rate measurements and solar neutrino detector calibration. The study aims to enhance our understanding of reactor physics and neutrino properties.

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Production of Electron Neutrinos from Reactor and the Physics Potentials

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  1. Production of Electron Neutrinos from Reactor and the Physics Potentials • M-C simulation of reactor e flux; • Data analysis for the limits of electron neutrino magnetic moment and the 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 2004.07@Osaka

  2. 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

  3. 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

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

  5. 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 ?

  6. Total flux of electron neutrinoemitted 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

  7. 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;

  8. 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

  9. SIMULATION RESULT

  10. Simulation result Preliminary Electron neutrino are mainly contributed by Cr-50 in control rods; Neutrino flux at detector position due to Cr-50 is: 1.2×109 cm-2s-1

  11. Cross check & constraints • Leakage neutrons out of the reactor core < 1%; • K-eff: =1 for a critical system • Relative U-238 fission fraction: ~5% • U-239 production rates: ~0.6 • Reference neutron spectrum

  12. Cross check—— K-eff calculation; Cross check and constraints Fission neutrons are mostly absorbed by fuel rods, control rodsand water;

  13. Comments of cross check Based on the simulation • The U239 production rate per fission is 0.7; • Φn=0.28*1014 for thermal neutron flux; • A control rod assembly fraction of ξ=0.1 contains 13 kg Cr-50 or N=1.6*1026; • The Cr-51 production rate per fission at K-eff=1(ξ=0.1) is 0.0012; • For 3 GW thermal power output, the Cr-51 production rate is Rnγ = 7.2*1016 s-1; • Only less than 1% neutrons leave the reactor pressure vessel enclosing the core.

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

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

  16. Data analysis——fitting of the e

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

  18. 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 …

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

  20. Isotope IA(%) σnγ(barns) Τ1/2 QEC(MeV) BR(%) Physics potential Cr-50(n) 4.345 15.9 27.7d 0.753 100 Cr-50(p) 100 Cu63(n) 69.17 4.5 12.7h 1.675 61 Cu63(p) 100 Ge70(n) 21.23 3.15 11.43d 0.232 100 Ge70(p) 100 Eu151(n) 47.8 5900 13.516y 9.3116h* 1.874 1.92* 72.1 28* Eu151(p) 100 Candidate isotopes to enhance theνe flux

  21. Physics potential CC event rate e.g 71Ga(ne, e－)71Ge • At neutrino flux: ~1012cm-2s-1 ; • 10 tons target materials in nature; Applications (under studies) : s(nNCC) measurements; solar-n detector calibration ; oscillation studies … e.g. q13 (?)

  22. To complete list • Get more correct U-238 production rate  0.6; • Get correct relative U-238 fission rate  ~5% • Goal: accuracy- 20~30% natural core ; 5-10% loaded core ; • Complete radiative decay analysis; • Select the loaded candidate isotope with best FOM. • Study potential neutrino physics applications.

  23. Conclusion • Power plant can emit electron neutrino, we perform the M-C simulation for the neutrino flux； • The simulation result has been applied for TEXONO experiment data analysis to deduce the limits of magnetic moment and radiative decay lifetime of electron neutrino; • The physics potential of the reactor neutrino experiment has been discussed.

  24. Thanks !

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