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Rezo Shanidze

MC Studies in Erlangen & Neutrinos from SN in KM3NeT ?. Rezo Shanidze. KM3NeT Meeting, Catania, 11-13 March, 2008. MC Optimization Studies. S. Kuch, PhD thesis, www.slac.stanford.edu/spires/find/hep/www?r=FAU-PI1-DISS-07-001.

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Rezo Shanidze

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  1. MC Studies in Erlangen & Neutrinos from SN in KM3NeT ? Rezo Shanidze KM3NeT Meeting, Catania, 11-13 March, 2008

  2. MC Optimization Studies S. Kuch, PhD thesis, www.slac.stanford.edu/spires/find/hep/www?r=FAU-PI1-DISS-07-001 MC simulations of the different detector configurations. Comparison of thebenchmark parameters: Neutrino effective area Aeff(En) Angular resolution of reconstructed m: Q(m) Different detector components and geometry configurations were considered : PMT . . . PMT OM . . . OM • Photo-multipliers (PMT) Storey Storey . . . Storey • Optical modules (OM) Detection unit Detection unit . . . Detection unit • Storey on detection • unit (string) Geometry configuration R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  3. PMTs / Optical Modules/ Storeys PMTs used in the Erlangen MC simulations: 1) Standard: 10” Hamamatsu R7081 2) Small: 3” Photonis XP53X2 OM/storey: with large PMT a) OM with one 10” PMT b) Two OMs with 10”PMT c) ANTARES type with 3 OMs d) ANTARES type with 6 OMs with Multi-PMT OM e) Storey with 3 cylindrical OMs f) Storey with spherical OM: 36 or 42 PMTs g) Storey with spherical OM: 21 PMTs. R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  4. Geometry configurations Basic geometry configurations: homogeneous (a), cluster (b) , ring (c,d) a b c d R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  5. The Reference Detector 15 x 15 strings ( 95 m) 37 storey (8325 OMs) 16.5 m 1 Multi-PMT OM 21x 3’’ PMT Instrumented volume 1.05 km3 Max m-track length (time) in KM3NeT ~ 2 km (7 msec) R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  6. MC Data in Erlangen • MC data produced in Erlangen (with modified ANTARES software): • Gendet - GENHEN - km3 - RECO • For each detector configuration, 2 x109 simulated events • nmN CC interactions: E-1.4, 10 < En < 107 GeV, -1 <cosQn<1 • Data sample for the reconstruction: ~ 8 x104 events / configuration What can we study from these data samples: - neutrino event rates ? - comparison to other experiments ? . . . What has to be studied for TDR ? . . . . . R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  7. Effective area and event rates • Neutrino effective area AEff(En)defines the neutrino event rates for a given • neutrino flux F(En) ( cosmic neutrinos ~E -2) • dN/dt = ∫F(En) AEff(En) dEn  (En )    NA V  e  PEarth ~ R=sCC(nN) /sCC(nN) R. Gandhi et al, Phys.Rev. D58(1998), 093009 Correction factor for nm = ½(nm + nm) ~ R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  8. EffectiveArea: KM3NeT vs IceCube Neutrino effective area for KM3NeT (4p, nm) and IceCube (2p). IceCube eff. Area (arXiv:0712.3524v1, provided by A.Kappes ) KM3NeT IceCube KM3NeT: x 1.73 storeys/OM 8325/4800 x 3.27 photocathode area 1.73 x [21 x(0.3)2] R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  9. MC event time Deep-sea neutrino detector: the hit rates are defined from K40 K40 hits in ANTARES MC ( K40 3545 500 ) i i Event time in MC : a time interval between muon hits + 2DtK40 MC event time: Dt ~ 1 ms ( at low energies ) NK40 ~ NPMT RK40DtK40 ~ 620 logN ~ 2.8 rate/PMT ± Dtk4o time(ns) R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  10. Preliminary limits Physics sensitivity for diffuse neutrino flux and flux from the neutrino point sources, for E-2 . ( From S. Kuch, PhD thesis ) Upper limit (90%CL) for neutrino diffuse flux obtained for ‘reference detector’. (For 1y of data taking) Upper limit of neutrino flux from the point sources as a function of source declination. R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  11. Summary • MC studies in Erlangen were devoted to the KM3NeT detector • optimization for nm CC interactions. • For the fast comparison of the benchmark parameters for different • detector configurations, only Cherenkov photons produced by m • were considered in simulations. • Further studies of the KM3NeT physics sensitivity (with the • selected detector configuration ) should include the processes not • considered in the optimization studies. For example: • - CC interaction of anti-neutrinos • - Cherenkov photons from the hadronic part of nmN interactions. • - Energy estimation of reconstructed m • - Online filter / “KM3NeT event” model. • . . . • - Bkg. rejection with multi-PMT OMs. • - m angular resolution vs. OM time resolution. R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  12. Neutrinos from SN in KM3NeT ? - Very preliminary study, based on the simple approximations. - To be confirmed with the MC simulations. Considered IceCube /SNEWS presentation at DPG-08, Freiburg The SN neutrino studies for ANTARES: S. Basa, ANTARES-PHYS-1998-003. On the possibility to detect supernovae explosions with a deep underwater neutrino telescope Y. Becherini, G.Ramadoni, M.Spurio, ANTARES-PHYS-2002-002. Detection of ne from Supernovae with ANTARES Study in Erlangen: A. Thurn, Supernovae detection with the ANTARES neutrino telescope ~ R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  13. The SN Early Warning System http://snews.bnl.gov/ The goal of SNEWS is to provide the astronomical community with a prompt alert of the occurrence of a Galactic core collapse event. Technical description of the SNEWS: New J. Phys. 6(2004),114 [ astrpo-ph/0406214] current status: K. Scholberg, ArXiv: 0803.0531v1 ( 4 March) The SN prompt alert g International network of neutrino experiments: Super-K, LVD, IceCube/AMANDA ( SNO until 2006) False alert rate of SNEWS < 1 century: Minimum acceptable level for 10s coincidence: 2 experiments, each with a false alarm rate ≤1 per week. SN 1987A was the last supernova visible in our skies and the first from which scientists detected neutrinos. Hubble Heritage Team (AURA / STScI / NASA) snews.bnl.gov Expected SN rate in our Galaxy ~1-3 / century Important not to miss ! R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  14. Neutrinos from SN • In a core collapse of a massive star • (SN Type II) 99% of binding energy • released in n : • e+e-gnlnl( l=e,m,t) • neutrino energy distribution (Fermi): • The positrons are produced in an inverse b reaction (electron antineutrino): • ne + p g n + e+, [ s(nep g ne+) >> s(negne) ] • Threshold energy: • En > Dmnp + me ~ 1.8 MeV, • En> 2.1 for positrons g Cherenkov photons (for n=1.33) • “SN positrons” : ~ 10-15 cm/water ( K40 electrons ~ 1 cm ) Neutrino (Fermi) and Boltzmann distribution for kT=5 MeV (from A.Thurn) R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  15. The SN Neutrinos in a neutrino telescope • First suggested for AMANDA: • F. Halzen, J. E. Jacobsen and E. Zas, • Phys. Rev. D49(1994), 1758 • Search for SN neutrinos in AMANDA: • Astropart. Phys. 16(2002), 345 • Predicted excess of N(p.e.) in a with NOM (10s): • Veff – Effective volume per OM for AMANDA • Probability of “false SN” signal < 10-9 ( < 1 / century for Dt=10s interval) • SN detection significance = N/s > 6 11 - events in Kamiokande-II 2.14kton – target mass of Kamiokande-II 52 kpc - distance to SN1987A R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  16. The SN Neutrinos in a neutrino telescope • For bkg. s1pe = ( NOM R Dt)½ , • Number of hits from SN neutrinos: • NS= NOMDR Dt • SN detection significance: • NS/s= DR x [( NOM /R) Dt )]½ • Taking Veff ~ 450 m3, SN1987 type supernova • at d=8 kpc gDR = 10 Hz / OM (IceCube). Veff as a function of OM number number in the AMANDA string 1. V eff ~ A x Labs VKM3MeT ~ (1 ÷ 2) x VICeCube Large absorption length (Labs) of IceCube is compensated by KM3NeT photocathode area (A) and QE. Very small effect per OM, only DR=10 Hz (factor f=1.000125 for 80kHz) is giving a significant signal in KM3NeT : ~ 10 s. R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  17. KM3NeT (?) AMANDA-II AMANDA-B10 IceCube 30 kpc KM3NeT Sensitivity to the Galactic Supernovae With 6s significance IceCube is sensitive to SN1987A type signal from a distance d < 30 kpc. Similar sensitivity (very preliminary ! ) of KM3NeT reference detector, d<10(20) kpc ( > 50% stars in our Galaxy ) Number of fake SN alerts in IceCube < 15 y-1 The distribution f(r) of progenitor stars in the Milky Way, located within a distance r(kpc) from the Earth. ( Astropart. Phys.,16(2002), 345) R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  18. SN detection significance From ANTARES PHYS-2002-002 (table 4) Increase signal to bkg. ratio. Decrease bkg: ( > 1/f2 ) signal: (< 1/f ) Can be studied only in the dedicated MC simulations. For example in ANTARES-PHYS-2002-002: - 1 pe, 2 pe, 3 pe. hits/rates - coincidence rates (c1, c2) in a single storey for Dt = 25, 50, 100, 500 ms and 10s (Table 4) Similar studies in Erlangen: for the coincidence (c1) rates (A. Thurn) For “Flykt-OM” more options are possible: For example, k-hit coincidence rate from n PMTs in a storey for bkg suppression . If p=Rotc << 1, Rk≈ C(n,k) pk R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  19. Bioluminescence • Largest time varying background in KM3NeT. • - Can bioluminescence illuminate the whole KM3NeT • detector during a short time (Dt=10s) ? • - How often bioluminescence will give a false SN alarm ? • ANTARES data can be used for bioluminescence • analysis as an input for the MC simulations. R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

  20. Summary • First consideration indicates, that KM3NeT can detect the SN neutrinos as a significant excess of OM rates (~6s) in a short time interval (~10 s) . • If a SN false alarm rate due to bioluminescence is not too high, ( ≤ 1/week) KM3NeT can be used in the SNEWS alert network. • MC simulations are necessary for the confirmation and studies the KM3NeT detector Galactic Supernovae detecting capabilities. R.Shanidze, KM3NeT Meeting, Catania, 12/03/2008

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