Proton decay and neutrino astrophysics with the future LENA detector

Transcription

1 Proton decay and neutrino astrophysics with the future LENA detector Teresa Marrodán Undagoitia Institut E15 Physik-Department Technische Universität München Paris,

2 Outline 1 LENA physics and design 2 Proton decay and particle physics in LENA 3 Neutrino astronomy 4 Liquid scintillator measurements 5 Summary

3 Outline 1 LENA physics and design 2 Proton decay and particle physics in LENA 3 Neutrino astronomy 4 Liquid scintillator measurements 5 Summary

4 Low Energy Neutrino Astronomy

5 LENA Particle physics Neutrino astronomy Measurements Summary Pre-feasibility study: Pyhäsalmi site -> Talk by Guido Nuijten Studies for other sites: on-going within LAGUNA DS

6 Outline 1 LENA physics and design 2 Proton decay and particle physics in LENA 3 Neutrino astronomy 4 Liquid scintillator measurements 5 Summary

7 Proton decay Theoretically favored modes p e + π 0 p K + ν -> clear signature in liquid scintillators Predicted lifetimes: τ y Super-Kamiokande best limits: τ(p e + π 0 ) y (90% C.L.) τ(p K + ν) y (90 % C.L.)

8 Free proton decay p K + ν T (K + ) = 105 MeV K + µ + ν µ 63.43% T (µ + ) = 152 MeV τ(k + ) = 12.8 ns K + π + π % T (π + ) = 108 MeV T (π 0 ) = 110 MeV

9 Free proton decay p K + ν T (K + ) = 105 MeV K + µ + ν µ 63.43% T (µ + ) = 152 MeV τ(k + ) = 12.8 ns K + π + π % T (π + ) = 108 MeV T (π 0 ) = 110 MeV

10 Background rejection Pulse-shape analysis on the risetime proton decay efficiency of 65%

11 Energy spectrum (180 pe/mev) Two peaks: Kaon + Muon: 257 MeV Kaon + Pions: 459 MeV Efficiency: ε E = Included: protons from 12 C Potential of LENA (10 y measuring time) For Superkamiokande current limit: τ = y o About 40 events in LENA and 1 background Limit at 90% (C.L) for no signal in LENA: o τ > y with ɛ = 65% Phys. Rev. D 72, (2005)

12 Proton decay p e + π 0 First calculation: Good energy resolution of LS (< 1%) Narrow energy cut: B < 1 event/y Low efficiency (ɛ =12%) Achievable sensitivity in 1 year: τ few y Possible improvement: background discrimination via tracking fast scintillator and electronics required

13 Reactor neutrinos with LENA S. T. Petcov and T. Schwetz, Phys. Lett. B642, 487 (2006) Determination of θ 12 and m 2 12 For the Fréjus location After one year measuring time, 3σ precision on oscillation parameters: 20% on θ 12 and 3% on m 2 12 J. Kopp et al., JHEP 01, 053 (2007) Using a mobile ν e source (e.g. a nuclear powered ship) For an underwater detector location sin 2 2θ 13 < after about 3 years

14 Indirect dark matter search S. Palomares-Ruiz and S. Pascoli, Phys. Rev. D 77, (2008) Annihilation of light WIMPs χχ νν ν e energy spectrum in 10 y Clear signature of ν e in liquid scintillator Background from reactor, atmospheric and diffuse supernove neutrinos

15 Outline 1 LENA physics and design 2 Proton decay and particle physics in LENA 3 Neutrino astronomy 4 Liquid scintillator measurements 5 Summary

16 Supernova detection 8 M ( erg) at D = 10 kpc (galactic center) In LENA detector: events Possible reactions in liquid scintillator ν e + p n + e + ; n + p d + γ ν e + 12 C 12 B + e + ; 12 B 12 C + e + ν e ν e + 12 C e + 12 N; 12 N 12 C + e + + ν e ν x + 12 C 12 C + ν x ; 12 C 12 C + γ ν x + e ν x + e (elastic scattering) 680 ν x + p ν x + p (elastic scattering) Diploma thesis by J.M.A. Winter (TU München)

17 Diffuse Background of Supernovae Neutrinos ν e -neutrino spectrum In LENA detector: (44 kt f.v.) ν e + p n + e + Event rate in 10 y: LL: 110 events TBP: 60 events (discrimination power at > 2 σ ) M. Wurm et al., Phys. Rev. D (2007) Information about Star Formation Rate for (0 < z < 1)

18 Solar neutrinos Rates of solar neutrino events In the LENA fiducial volume: m 3 Borexino experiment -> First 7 Be neutrino measurement 7 Be ν s: 5400 d 1 Small time fluctuations pep ν s: 150 d 1 Information about the pp-flux Solar luminosity in ν s CNO ν s: 210 d 1 Important for heavy stars 8 B ν s: CC on 13 C: 360 y 1

19 Geoneutrinos Unexplained source of heat flow on Earth Unknown contribution of natural radioactivity How are 238 U, 232 Th distributed in core, mantle and crust? In liquid scintillator: ν e + p n + e + K. Hochmuth et al., Astropart. Phys. 27 (2007) 21 In LENA detector: ( ) events/y (Scaling KamLAND results) 238 U/ 232 Th separation due to spectral form

20 Outline 1 LENA physics and design 2 Proton decay and particle physics in LENA 3 Neutrino astronomy 4 Liquid scintillator measurements 5 Summary

21 Fluorescence decay-time measurements Motivation: PD identification Photon counting method 54 Mn source: 834 kev γ s PMT s time jitter: σ = 0.9 ns

22 LENA Particle physics Neutrino astronomy Measurements Summary Scintillator spectra: UV-Lamp UV-radiation: D2 lamp Spectroscopy of the emitted light Ocean optics spectrometer

23 Light propagation Scattering length λ s 15 m Angle dependence of the scattered light Study of polarized and unpolarized light Attenuation length λ 10 m Effects of absorption and scattering in the propagation 1 λ = 1 λ s + 1 λ a Planned measurement: Scintillator quenching R&D on liquid scintillators -> Talk by Christian Buck

24 Outline 1 LENA physics and design 2 Proton decay and particle physics in LENA 3 Neutrino astronomy 4 Liquid scintillator measurements 5 Summary

25 Summary Lena physics Good sensitivity for proton decay via p K + ν Reactor neutrinos and indirect DM search Supernova neutrinos Solar neutrino measurements Liquid scintillator developments Experiments to light production: fluorescence and spectroscopy Study of light propagation: scattering and attenuation lengths