LENA Low Energy Neutrino Astrophysics F F. von Feilitzsch, L. Oberauer, W. Potzel Technische Universität München LENA Delta.

Präsentation zum Thema: "LENA Low Energy Neutrino Astrophysics F F. von Feilitzsch, L. Oberauer, W. Potzel Technische Universität München LENA Delta."—  Präsentation transkript:

1 LENA Low Energy Neutrino Astrophysics F F. von Feilitzsch, L. Oberauer, W. Potzel Technische Universität München LENA Delta

2 LENA (Low Energy Neutrino Astrophysics) Idea: A large (~30 kt) liquid scintillator underground detector for Galactic supernova neutrino detection Relic supernovae neutrino detection Terrestrial neutrino detection Search for Proton Decay Solar Neutrino Spectroscopy Neutrino properties

3 P - decay event Scintillator: PXE, non hazard, flashpoint 145° C, density 0.99, ultrapure (as proven in Borexino design studies) N pe ~ 100 / MeV beta H2OCerenkov veto 30 KT scintillator

4 Possible locations for LENA ? Underground mine ~ 1450 m depth, low radioactivity, low reactor background ! Access via trucks

5 loading of detector via pipeline transport of 30 kt PXE via railway no fundamental security problem with PXE ! no fundamental problem for excavation standard technology (PM-encapsulation, electronics etc.) LENA is feasible in Pyhäsalmi !

6 Pylos (Nestor Institute) in Greece, on the Cern Neutrino beam (off axis) D~1700 km

7 Neutrino interactions in the scintillator υ elastic scattering υ(x) + e υ (x) + p υ(x) + p ν- inverse ß-decay _ ν(e) + p n + e(+) υ nuclear excitation 12C 12B 12N 17.3 MeV13.4MeV 15.1MeV 1+ 20ms 1+ 11ms 1+ ec delayed coincidence υ(e) interaction υ(x) interaction

8 Galactic Supernova neutrino detection with Lena Electron Antineutrino spectroscopy ~ 65 Electron spectroscopy ~ 65 ~ 4000 and ~ 2200 Neutral current interactions; info on all flavours ~ 4000 and ~ 2200 ~7800 ~ 480 Event rates for a SN type IIa in the galactic center (10 kpc)

9 Visible proton recoil spectrum in a liquid scintillator all flavors and anti-particles dominate J. Beacom, astro-ph/0209136

10 Supernova neutrino luminosity (rough sketch) Relative size of the different luminosities is not well known: it depends on uncertainties of the explosion mechanism and the equation of state of hot neutron star matter T. Janka, MPA

11 SNN-detection and neutrino oscillations with LENA Dighe, Keil, Raffelt (2003) Modulations in the energy spectrum due to matter effects in the Earth

12 Scintillator good resolution Water Cherenkov Dighe, Keil, Raffelt (2003) SNN-detection and neutrino oscillations Modulations in the energy spectrum due to matter effects in the Earth

13 Preconditions for observation of those modulations SN neutrino spectra e and are different distance L in Earth large enough very good statistics very good energy resolution

14 LENA and relic Supernovae Neutrinos SuperK limit very close to theoretical expectations Threshold reduction from ~19 MeV (SuperK) to ~ 9 MeV with LENA __ Method: delayed coincidence of e p e(+) n Low reactor neutrino background ! Information about early star formation period

15 SRN No background for LENA ! Reactor SK Reactor bg LENA ! Atmospheric neutrinos LENA SNR rate: ~ 6 counts/y

16 Solar Neutrinos and LENA: Probes for Density Profile Fluctuations ! 7-Be ~200 / h LENA Balantekin, Yuksel TAUP 2003 hep- ph/0303169

17 Terrestrische Neutrinos und LENA was ist die Quelle des terrestrischen Wärmeflusses? welchen Beitrag liefert die Radioaktivität? wieviel U, Th ist im Mantel? ist ein gigantischer natürlicher Kernreaktor im Zentrum die Energiequelle des Erdmagnetfelds?

18 Wärmefluss aus der Erde Es wird ein kleiner Wärmefluss aus der Erde gemessen. 80 mW / m 2 80 mW / m 2 Integral: H E 4 10 13 W = 40 TW (Unsicherheit ~20%): Das entspricht der Leistung von etwa 10 4 Kernkraftwerken!

19 Die Kruste und der oberste Teil des Mantels sind einer direkten geochemischen Analyse zugänglich. Die Theorie: U, K und Th sind lithophil, sie akkumulieren in der (kontinentalen) Kruste. Danach könnte die ~30 km Kruste soviel U, Th wie der ~3000 km dicke Mantel enthalten. extrapoliert U, Th im unteren Teil des Mantels wird extrapoliert von Daten aus dem oberen Mantel. Wo befindet sich U, Th? U In der (kont.) Kruste M c (U) (0.2-0.4)10 17 kg. Noch größere Unsicherheiten für den Mantel: ? M m (U) (0.2-0.8)10 17 Kg ? crust Upper mantle

20 KAMLAND: ein erster Blick… N(Th+U) 6 Monate Daten ergibt einen Fit für N(Th+U) für E< 2.6 MeV N(Th+U) = 9 6* N(Th+U) = 9 6* Die Unsicherheit* ist dominiert durch Fluktuation der Reaktorsignale Das Ergebnis ist mit jedem geophysikalischen Modell konsistent: H rad =(0-100 TW).

21 Proton Decay and LENA Proton Decay and LENA p K p K SUSY This decay mode is favoured in SUSY theories The primary decay particle K is invisible in Water Cherenkov detectors It and the K-decay particles are visible in scintillation detectors Better energy solution further reduces background

22 P K + event structure: T (K + ) = 105 MeV nsec K + 63.5 %) K + T ( + ) = 152 MeV T ( + ) = 108 MeV electromagnetic shower E = 135 MeV e + s) e + s) MeV) e + s) e + s)

23 3 - fold coincidence !3 - fold coincidence ! the first 2 events are monoenergetic !the first 2 events are monoenergetic ! use time- and position correlation !use time- and position correlation ! How good can one separate the first two events ?....results of a first Monte-Carlo calculation

24 K time (nsec) K P decay into K and Signal in LENA

25 Background Rejection: monoenergetic K- and - signal! position correlation pulse-shape analysis (after correction on reconstructed position)

26 SuperKamiokande 170 1489 33% ) SuperKamiokande has 170 background events in 1489 days (efficiency 33% ) LENA ~ 5 / y LENAIn LENA, this would scale down to a background of ~ 5 / y and after PSD-analysis this could be suppressed in LENA to ~ 0.25 / y~ 70% ~ 0.25 / y ! (efficiency ~ 70% ) 10 34 a few 10 34 years K-decayA 30 kt detector (~ 10 34 protons as target) would have a sensitivity of a few 10 34 years for the K-decay after ~10 years measuring time SUSY SU(5)K-decay dominant10 29 y to 10 35 yThe minimal SUSY SU(5) model predicts the K-decay mode to be dominant with a partial lifetime varying from 10 29 y to 10 35 y ! SK actual best limit from SK : 6.7 x 10 32 y (90% cl)

27 Conclusions LENA LENA a new observatory complemntary to high energy neutrino astrophysics fundamental impact on e.g. geophysics, astrophysics, neutrino physics, proton decay Pyhäsalmi) feasibiluty studies very promising (Pyhäsalmi) costs ca. 100 - 200 M

28 ...some more aspects of Lena Complementary to high energy neutrino astronomy Long term (~decades) experiment Large European intiative