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Ho Ling Li Mentor: Karsten Heeger Department of Physics December 3, 2008

Neutrino spectral calculations at the Daya Bay detectors and Relations between neutrinos and CPT violations. Ho Ling Li Mentor: Karsten Heeger Department of Physics December 3, 2008. What is neutrino oscillation?.

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Ho Ling Li Mentor: Karsten Heeger Department of Physics December 3, 2008

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  1. Neutrino spectral calculations at the Daya Bay detectorsandRelations between neutrinos and CPT violations Ho Ling Li Mentor: Karsten Heeger Department of Physics December 3, 2008

  2. What is neutrino oscillation? • Neutrinos have three different types (flavors): νe, νμ, ντ, and different masses • Quantum mechanics predicts change of flavors when neutrinos travel in space • Oscillation equation (probability of appearance): parameter that we want to measure (GOAL!) (difference of mass)2 Units: [Δm2] = eV2; [L] = m; [E] = MeV distance (L) energy Ho Ling Li Univ. Wisconsin Dec 3, 2008

  3. The Daya Bay Reactor Neutrino Experiment – an introduction • Located in Guangdong province of China • Study neutrino oscillation by using the electron antineutrinos released during the fission process at Daya Bay Nuclear Power Plant and Lingao Nuclear Power Plant • Aim to make a precise measurement of the neutrino mixing angle θ13 with a sensitivity of 0.01 in sin2(2θ13) by measuring the flux and spectrum of electron antineutrinos Ho Ling Li Univ. Wisconsin Dec 3, 2008

  4. Goals of my research • Calculate the predicted spectrum of antineutrinos at the three detector sites of the Daya Bay experiment • Study and compare the spectral distortions due to fuel compositions and neutrino oscillation Ho Ling Li Univ. Wisconsin Dec 3, 2008

  5. Step 1: fuel composition and variation of Daya Bay Reactors • Fresh fuel composed of 3.2% 235U and 96.8% 238U • Fuel composition changes throughout the fission process and Pu isotopes are produced • 235U, 238U, 239Pu, 241Pu are the four main isotopes that undergo fissions and produce anti-νe http://whyfiles.org/186ed_teller/images/fission_anim.gif Ho Ling Li Univ. Wisconsin Dec 3, 2008

  6. Step 2: the antineutrino spectra from fuel isotopes • data obtained from: Vogel, P., G.K. Schenter, F.M. Mann, R.E. Schenter. Reactor antineutrino spectra and their application to antineutrino-induced reactions II. Physical Review C, 24, 1543 (1981). Pu-241 U-238 U-235 # of antineutrinos / cm2 / s Pu-239 antineutrino energy (MeV) Ho Ling Li Univ. Wisconsin Dec 3, 2008

  7. Step 3: calculate the antineutrino spectra at a reactor capacity × (3.125 × 1016 fissions/second/Mwatt) The ratios of electron antineutrinos produced by the isotopes concerned The capacities of the reactors at Daya Bay The number of fissions of each isotope per second in different reactor cores Ho Ling Li Univ. Wisconsin Dec 3, 2008

  8. Step 4 & 5: calculate predicted spectra at detectors # of neutrinos antineutrino energy (MeV) 2.5 x 10-3eV2 assume sin2(2θ13) = 0.1 Units: [Δm2] = eV2; [L] = m; [E] = MeV the only variable in the spectra Ho Ling Li Univ. Wisconsin Dec 3, 2008

  9. Step 4 & 5: calculate predicted spectra at detectors • at Daya Bay Near Detectors spent (with oscillation) fresh (without oscillation) fresh (with oscillation) spent (without oscillation) Ho Ling Li Univ. Wisconsin Dec 3, 2008

  10. spent (without oscillation) spent (with oscillation) fresh (with oscillation) fresh (without oscillation) Step 4 & 5: calculate predicted spectra at detectors • at Far Detectors Ho Ling Li Univ. Wisconsin Dec 3, 2008

  11. Comparison of the Spent Fuel and Oscillation Spectra Effect of Spent Fuel Effect of Neutrino Oscillation The difference between the normalized fresh fuel spectra with and without the signature of neutrino oscillation over the normalized fresh fuel spectra without the signature of neutrino oscillation at the Far Detector The difference between the normalized spectra of the fresh fuel and the spent fuel over the normalized spectra of the fresh fuel ratio ratio antineutrino energy (MeV) antineutrino energy (MeV) Ho Ling Li Univ. Wisconsin Dec 3, 2008

  12. Conclusions • Both the variation of the fuel compositions and neutrino oscillation effects lead to spectral distortions • The way they change the spectral shapes is distinct • The neutrino oscillation angle can be measured independent of the fuel compositions Ho Ling Li Univ. Wisconsin Dec 3, 2008

  13. Relations between neutrinos and CPT violations

  14. Relations between CPT violations and ν • When there is CPT violation… • Mixing angles and the mass difference ∆m of ν and νcan be different • 12≠ 12, 13 ≠ 13, 23 ≠ 23 • ∆m12 ≠ ∆m12, ∆m13 ≠ ∆m13 Univ. Wisconsin Dec 3, 2008

  15. Past and Present Bounds • S. Antusch, E. Fernandez-Martinez (2004) get: • | sin212–sin212| < 0.3 • Neutrino 08 • | sin212 – sin212| < 0.3 • No improvement… Univ. Wisconsin Dec 3, 2008

  16. Comparison with best CPT bounds from K0, K0 • |mK - mK| < 0.44 x 10-18 GeV • |mK - mK| / maverage< 10-18 • 493 MeV < mK < 498 MeV • => |mK - mK| < 0.5 x 10-18 GeV • No improvement neither… Barger, Pakvasa, Weiler, and Whisnant. (2000) PDG. (2007) Univ. Wisconsin Dec 3, 2008

  17. Requirements for CPT symmetry to hold • Lorentz invariance • Locality • If extra dimension exists, interactions that are local in extra dimension “look” non-local in our world brane • Therefore, Lorentz invariance holds, but there is CPT violation 5D 4D brane Univ. Wisconsin Dec 3, 2008

  18. Lorentz violation in neutrinos? • P = 1 - 0.92 sin2(17.29 x / L0 + k*L0 / x), x = L0/E • tan2(12) = 0.56, ∆m2 = 7.58 x 10-5 eV2 • k = 0.005, k = 0.01, k = 0.02, k = 0.04, k = 0.08 Univ. Wisconsin July 1, 2008

  19. Consequence of Lorentz invariance violation • mwill be frame dependent • However, if the Lorentz invariance is broken at very high energy scale (e.g. Planck scale), the corrections will be extremely small (mc2)2 = E2 - (pc)2 Univ. Wisconsin Dec 3, 2008

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