Potential of the large liquid-scintillator detector LENA in particle and astrophysics

Transcription

1 Potential of the large liquid-scintillator detector LENA in particle and astrophysics Teresa Marrodán Undagoitia Institut E15 Physik-Department Technical University of Munich DPG Teilchenphysik Dortmund Teresa Marrodán Undagoitia (TUM) LENA Detector Dortmund / 12

2 Outline 1 Proposed LENA Detector 2 Physics Supernovae Neutrinos Geoneutrinos Proton Decay 3 Summary Teresa Marrodán Undagoitia (TUM) LENA Detector Dortmund / 12

3 Proposed LENA Detector Detector scheme Size 100 m length 30 m Liquid Scintillator ton PXE Photomultipliers units 30% coverage Photoelectron yield 110 pe/mev Underground location Preferred site: Mine in Pyhäsalmi (Finland) Teresa Marrodán Undagoitia (TUM) LENA Detector Dortmund / 12

4 Supernovae Neutrinos First SN measurement: SN1987A Kamiokande: 11 events IMB: 8 events D = 10 kpc (center of our galaxy) 8 M ( E = erg) Superkamiokande In LENA detector: events Teresa Marrodán Undagoitia (TUM) LENA Detector Dortmund / 12

5 Detection of Supernovae Neutrinos Possible reactions in liquid scintillator ν e + p n + e + (Q=1.8 MeV) n + p d + γ; E γ = 2.2 MeV 8700 events ν e + 12 C 12 B + e + (Q=17.3 MeV) 12 B 12 C + e + ν e ; τ 1/2 = ms 494 events ν e + 12 C e + 12 N (Q=13.4 MeV) 12 N 12 C + e + + ν e ; τ 1/2 = ms 85 events ν x + 12 C 12 C + ν x with 12 C 12 C + γ; E γ = MeV 2925 events ν x + e ν x + e (elastic scattering) 610 events ν x + p ν x + p (elastic scattering) 7370 events Teresa Marrodán Undagoitia (TUM) LENA Detector Dortmund / 12

6 Geoneutrino Problem Unexplained source of heat flow on Earth Unknown contribution of natural radioactivity How are 238 U, 232 Th distributed in core, mantle and crust? Detection of ν e from 238 U, 232 Th decay chains Is it possible to have a nuclear reactor in the center of the Earth? Heat flow map Teresa Marrodán Undagoitia (TUM) LENA Detector Dortmund / 12

7 Geoneutrino First Detection: KamLAND Experiment ν e + p n + e events at 90% C.L. Detector measuring time: 749.1±0.5 d In LENA detector: 1500 events/y Teresa Marrodán Undagoitia (TUM) LENA Detector Dortmund / 12

8 Proton Decay: Theoretical Predictions Grand Unified Theories GUT s Dominant decay mode: p e + π 0 τ y Supersymmetry (SUSY) Dominant decay mode: p K + ν Extra dimensions (6D) Dominant decay mode: p e + π 0 String models Dominant decay mode: p e + π 0 τ y τ y τ ( ) y Superkamiokande: τ(p e + π 0 ) y (90% C.L.) τ(p K + ν) y (90 % C.L.) Teresa Marrodán Undagoitia (TUM) LENA Detector Dortmund / 12

9 Free Proton Decay Event Structure: p K + ν T (K + ) = 105 MeV τ(k + ) = 12.8 ns K + µ + ν µ 63.43% T (µ + ) = 152 MeV K + π + π % T (π + ) = 108 MeV T (π 0 ) = 110 MeV Number of photoelectrons Time Mean x Mean y RMS x RMS y Time in ns Number of photonelectrons Background muon with 257 MeV Time Mean x Mean y RMS x RMS y Time in ns Teresa Marrodán Undagoitia (TUM) LENA Detector Dortmund / 12

10 Background Rejection: Time Cut Detection efficiency: ε T = 0.65 Background suppression: B Number of Events 2400 Entries Mean RMS Time Intervals in the Risetime (ns) Number of Events Entries Mean RMS Time Intervals in the Risetime (ns) Teresa Marrodán Undagoitia (TUM) LENA Detector Dortmund / 12

11 Background Rejection: Energy cut Energy spectrum (110 pe/mev) Number of Events NumberPh Entries 1000 Mean 3.714e+04 RMS 1.192e Number of Photoelectrons Potential of LENA (10 y measuring time) Two peaks: Kaon + Muon: 257 MeV Kaon + Pions: 459 MeV Efficiency: ε E = Included: protons from 12 C For Superkamiokande current limit: τ = y 40 events in LENA und 1 background No signal in LENA: τ > y 90% (C.L) Teresa Marrodán Undagoitia (TUM) LENA Detector Dortmund / 12

12 Summary Technical feasibility studies very promising Flavour sensitivity and energy spectrum in supernovae neutrino measurements Diffuse background of supernovae neutrinos: Next Talk by Michael Wurm Measurement of solar neutrinos High statistics on geoneutrino flux ( 1500 events/y) A proton lifetime of τ y reachable in LENA (Phys. Rev. D 72 (2005) ; hep-ph/ ) Teresa Marrodán Undagoitia (TUM) LENA Detector Dortmund / 12