2009 11 20
Cosmic Ray PD D M P4
?
CR M f M PD MOA M1
ν ν
p+p+p+p 4 He +2e - +2ν e MeV e - + p n+ ν e γ e + + e - ν x + ν x p + p, γ + p π + X π µ + ν µ e + ν µ + ν e TeV p + p π + X π µ + ν µ e + ν µ + ν e GeV χ+ χ W + W µ + ν µ χ µ + ν µ
10 12 pp Solar ν e SN ν @G.C. cm -2 sec -1 MeV -1 10 8 10 4 1 10-4 B 8 reactor ν e Relic SN ν Atmospheric ν µ Neutrino flux at Earth 10-8 10-12 WIMP ν Astrophysical ν as BG 10-16 SK 10-20 10-2 1 10 2 10 4 Eν(GeV)
Two neutrino case () ν α = ( cosθ sinθ ( ) m2 = m2 2 -m 2 1 (ev 2 ) L (km): Neutrino flight length ν β ν 2 E (GeV): Neutrino energy -sinθ cosθ ) ν 1 P(ν α ν β ) = sin 2 2θ sin 2 (1.27 m 2 L/E) sin2θ ~1 ν e : ν µ : ν τ = 1 : 2 : 0 1 : 1 : 1 ν µ ν τ m 2 = 2.5 10-3 ev 2,sin 2 2θ=1.0 Losc= ~3000km@Eν=100GeV ν e ν µ ( ν τ ) m 2 =8 10-5 ev 2, sin 2 2θ=0.88 Losc= ~10 6 km@eν=100gev
( ~30 (E ν ~1GeV), ~1 E ν ~1TeV) ν E ν -2.7, ν E -2.0 (?) burst ) (WIMP Flavor (anti-ν e ν τ
Super-Kamiokande detector 42 m 50kt water Cherenkov 1000m underground ID viewd by 11176 PMT 2m thick OD for veto Fiducial mass 22.5kt E th ~5 MeV (~7MeV for SKII) 96~ 01 SK-I 02~ 05 SK-II (w/ half PMTs) 06~ SK-III (restore full PMTs) 39.3 m
History of Super-Kamiokande detector 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 SK I SK II SK III SK IV 11146 ID PMTs (40% coverage) 5.0 MeV ~4.5MeV Energy Threshold (Total energy) (Visible energy) SK I SK II SK III SK IV Acrylic (front) + FRP (back) 5182 ID PMTs (19% coverage) 7.0 MeV ~6.5MeV 11129 ID PMTs (40% coverage) 4.5 MeV ~4.0MeV Work in progress Electronics Upgrade < 4.0 MeV <~3.5MeV Target
Ring imaging Cherenkov ν + e ν + e ν Electron
Neutrino telescopes in operation Detector volume Muon effective area Super- Kamiokande ICECUBE ANTARES 50 kt (>5MeV) 0.0012 km 2 (>1.7GeV) ~1Gt (>100GeV) ~1km 2 ~10Mt (>100GeV) ~0.002km 2 (>100GeV) ~0.06km 2 (> 10 6 GeV) Super-Kamiokande ICECUBE ANTARES
ν N cross section 10-38 cm 2 / nucleon E ν (GeV) σ tot = ~ 10-38 cm 2 E ν /(GeV) 1 ν (@1GeV) 1 10-38 cm 2 6 10 32 N 3.15 10 7 s 190 int. cm 2 = s nucleon kton year kt yr ν-lepton ~30 @GeV) ~ 1 (@TeV)
ν SK FC ν PC Upgoing µ Stopping µ Through going µ µ µ µ 8.2/day 0.6/day 0.3day 1.1day 7-20MeV Energy spectrum of ν for each event category 1000 750 500 250 FC ν µ FC ν e PC ν µ 0 10 2 10 1 1 10 10 2 10 3 10 4 10 5 E (GeV) ν up-stop µ up-thru µ ν 9.9x10-5 BGν/sec
E ν Contained : σ Eν V=const N SK E ν µ : σ Eν V Eν N SK E 2 ν 1 TeV ν produces up-going through µ at SK Assuming E µ ~1TeV, R µ ~1000m Effective area S=1200m 2 1000m Effective target volume S x R µ x ρ rock 3x10 12 g N SK = 10 35 (cm 2 ) 10 7 (ν/cm 2 /s) 10 36 (proton) ~10-6 events/s µ ν
Two topics from neutrino astrophysics at Super-Kamiokande WIMP (Eν ~100GeV) (Eν~10MeV)
Neutrinos from WIMP annihilations
CR NZ MOA1.8m Super-Kamiokande WIMP XMASS MACHO Xe WIMP
WIMP WIMP WIMP WIMP WIMP- SI 10 4-10 6 m 2 ν 1kg Ge SD 10-500 m 2 ν 50g M.Kamionkowski Phys.Rev.Lett.74 5174(1995)
WIMP
DAMA DAMA LIBRA 250kg NaI)
or PAMELA e + /e - anomaly ATIC e + anomaly O.Adriani et al astro-ph0810.4995 J.Chang et al, Nature 456 07477 132GeV WIMP? Boost factor ~30000? Bergstrom, Bringmann,Edsjp astro-ph0808.3725 620GeV KK DM? Boost factor ~200?
Relic Super Nova Diffuse neutrinos
Neutrinos from SN1987a
Neutrino Flux (/cm2 /sec /MeV) 10 7 10 6 10 5 10 4 10 3 10 2 10 1 10-1 10-2 10-3 10-4 10-5 10-6 Supernova Relic Neutrino SRN SRN Reactor ν (ν e ) Solar 8 B (ν e ) Solar hep (ν e ) SRN (ν e fluxes) 0 10 20 30 40 50 60 70 80 Neutrino Energy (MeV) Constant SN rate (Totani et al., 1996) Totani et al., 1997 Hartmann, Woosley, 1997 Malaney, 1997 Kaplinghat et al., 2000 Ando et al., 2005 Lunardini, 2006 Fukugita, Kawasaki, 2003 (dashed) Atmospheric ν e e + p e + + n Expected SRN signal 0.8-5.0 events/year/22.5kton (10-30MeV) 0.3-1.9 events/year/22.5kton (18-30MeV)
30 25 20 15 10 5 90% CL limit of SRN Relic Search in SK-I I and SK-II (>18 MeV) SK-I (1496days) Total background Atmospheric ν µ invisible µ decay e Events/4MeV 16 14 12 10 8 6 4 2 SK-II(791 days) Atmospheric ν µ invisible µ decay e 0 20 30 40 50 60 70 80 SK1 DATA spectrum Atmospheric ν e 0 20 30 40 50 60 70 80 Atmospheric SK2 DATA ν e spectrum Spallation background Energy (MeV) Φ SK-I < 1.25 ν cm -2 s -1 Φ SK-II < 3.68 ν cm -2 s -1
/cm2/sec Flux limit VS predicted fluxes SK-II limit = 3.68 /cm 2 /sec (E>18MeV) Preliminary SK-I limit = 1.25 /cm 2 /sec Combined limit = 1.08 /cm 2 /sec Constant SN rate (Totani et al. 1996) Totani et al. 1997 Malaney et al. 1997) Hartmann Kaplinghat et al. et al. 1997) 2004 Ando et al. 2005 Fukugita et al. 2003 Lunardini et al. 2006 Observation is touching on the expectations
SFR vs SK limit M.Fukugita, M.Kawasaki, MNRAS 340(2003)7
events/10years/2mev ν e p e + n Gd 10 9 8 relic+b.g.(inv.mu 1/5) 7 6 5 4 3 2 1 B.G. inv.mu(1/5) atmsph. ν e 0 10 15 20 25 30 35 40 45 50 GADZOOKS! Visible energy (MeV) Relic model: Astropart.Phys.18, 307(2003) with flux revise in NNN05. γ 8MeV νe signal could be separated from BG by neutron tagging. Vertex correlation: ~50cm Load 0.2% Gd into SK water to detect gamma by neutron capture. (M.Vagins and J.Beacom) With 10 years SK data: Signal=33events, B.G.=27events (E vis =10-30 MeV) Assuming 67% detection efficiency. Assuming invisible muon B.G. can be reduced by a factor of 5 by neutron tagging. (will be checked in SK-IV by using 2.2MeV γ)
Summary 100GeV background rejection WIMP annihilation neutrino (<100GeV) Solar WIMP annihilation σ SD Relic Super Nova Diffuse neutrinos factor 5 Gd