LENA Delta Low Energy Neutrino Astrophysics F F

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

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

H 2 O Cerenkov veto Npe ~ 100 / Me. V beta P - decay event 30 KT scintillator Scintillator: PXE , non hazard, flashpoint 145° C, density 0. 99, ultrapure (as proven in Borexino design studies)

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

• 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 !

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

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 15. 1 Me. V υ(x) interaction 1+ 11 ms 1+ 1+ 20 ms 12 N 12 B υ(e) interaction 17. 3 Me. V 13. 4 Me. V ec delayed coincidence 12 C

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

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

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 Supernova neutrino luminosity (rough sketch) T. Janka, MPA

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

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

Preconditions for observation of those modulations • SN neutrino spectra ne and nm, t are different • distance L in Earth large enough • very good statistics • very good energy resolution

LENA and relic Supernovae Neutrinos • Super. K limit very close to theoretical expectations • Threshold reduction from ~19 Me. V (Super. K) to ~ 9 Me. V with LENA __ • Method: delayed coincidence of ne p -> e(+) n • Low reactor neutrino background ! • Information about early star formation period

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

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

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?

Wärmefluss aus der Erde • Es wird ein kleiner Wärmefluss aus der Erde gemessen. F » 80 m. W / m 2 • Integral: HE » 4 1013 W = 40 TW (Unsicherheit ~20%): • Das entspricht der Leistung von etwa 104 Kernkraftwerken!

Wo befindet sich U, Th? • 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. • U, Th im unteren Teil des Mantels wird extrapoliert von crust Upper mantle U In der (kont. ) Kruste Mc(U) » (0. 2 -0. 4)1017 kg. Noch größere Unsicherheiten für den Mantel: Mm(U) » (0. 2 -0. 8)1017 Kg ?

KAMLAND: ein erster Blick… • 6 Monate Daten ergibt einen Fit für N(Th+U) für E< 2. 6 Me. V • N(Th+U) = 9 ± 6* • Die Unsicherheit* ist dominiert durch Fluktuation der Reaktorsignale • Das Ergebnis ist mit jedem geophysikalischen Modell konsistent: Hrad=(0 -100 TW).

Proton Decay and LENA p Kn • 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

P -> K+ n event structure: T (K+) = 105 Me. V t (K+) = 12. 8 nsec K+ -> m+ n (63. 5 %) T (m+) = 152 Me. V K+ -> p+ p 0 (21. 2 %) T (p+) = 108 Me. V electromagnetic shower E = 135 Me. V m+ -> e+ n n (t = 2. 2 ms) p+ -> m+ n (T = 4 Me. V) m+ -> e+ n n (t = 2. 2 ms)

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

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

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

• Super. Kamiokande has 170 background events in 1489 days (efficiency 33% ) • In LENA, this would scale down to a background of ~ 5 / y and y after PSD-analysis this could be suppressed in LENA to ~ 0. 25 / y ! (efficiency ~ 70% ) y 70% • A 30 kt detector (~ 1034 protons as target) would have a sensitivity of t < a few 1034 years for the K-decay after ~10 years measuring time • The minimal SUSY SU(5) model predicts the K-decay mode to SU(5) K-decay be dominant with a partial lifetime varying from 1029 y to 1035 y ! dominant actual best limit from SK: t > 6. 7 x 1032 y (90% cl)

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