The evolution of high energy neutrino telescopes Christian Spiering DESY

The evolution of high energy neutrino telescopes …a long march which has not yet reached its end.

under- ground optical: - deep water - deep ice - air showers - radio - acoustics

under- ground optical: - deep water - deep ice - air showers - radio - acoustics This talk will essentially address the optical telescopes deep under water and in ice. See the written version for the high-energy frontier and the corrersponding techniques

Ann.Rev.Nucl.Sci 10 (1960) 63

Ann.Rev.Nucl.Sci 10 (1960) 1

Moisej MarkovBruno Pontecorvo M.Markov, 1960 : „We propose to install detectors deep in a lake or in the sea and to determine the direction of charged particles with the help of Cherenkov radiation“ Proc ICHEP, Rochester, p. 578.

Central interest: cross sections, W-mass … one of the main motivations for Reines‘ South Africa detector, the Kolar Gold Field Detector (India) and the Baksan scintillation detector. Early sixties: does the neutrino cross section saturate beyond 1 GeV (i.e. one would never measure atm. neutrinos with energies higher than a few GeV). The question was relaxed in the mid seventies:

First measurement of atmospheric neutrinos Beside several ideas like e.g.  H. Uberall and C. Cowan, 1965 CERN Conf. on Experimental Neutrino Physics, p. 231 –Downward looking PM observing a 10 m thick water target, „possibly in ocean or a lake“  V. Bogatyrev, Yad.Fiz 13 (1971) 336 –Three detectors each 10 7 tons of distilled water a several km depth, widely spaced  SN triangulation in 1965 detection of nearly horizontal atmospheric neutrinos by F. Reines in a South African Gold mine.

DUMAND  1973 ICRC, Reines, Learned, Shapiro, Zatsepin, Miyake: a deep water detector to clarify puzzles in muon depth-intensity curves  Puzzles faded away, but there remained the awareness that such a detector could also work as neutrino detector  The name: DUMAND (Deep Underwater Muon And Neutrino Detector), proposed by Fred Reines  1975: First DUMAND Workshop in Washington State College  DUMAND Steering Committee, chaied by F.Reines, J. Learned,. A.Roberts See also: A.Roberts: The birth of high-energy neutrino astronomy: a personal history of the DUMAND project, Rev. Mod. Phys. 64 (1992) 259.

 Principle and capabilities  Angular resolution of 1° possible  astrononomy  Energy resolution for muons is 50% at best, for 1 km track length

The DUMAND Workshops  An unbelievable source of basic ideas (including crazy ones which are sometimes the most exciting)  1976 Honolulu  1978 Scripps  1979 Khabarovsk/Baikal  1978 Honolulu  Plus dedicated workshops on deployment, acoustic detection, signal procressing and ocean engineering

Which physics?  UNDINE: UNderwater Detection of Interstellar Neutrino Emission –i.e. Supernova  too rarely to optimize an ocean detector for it (  IMB)  ATHENE: ATmospheric High-Energy Neutrino Experiment –Better with underground experiments  UNICORN: UNderwater Interstellar COsmic Ray Neutrinos –The high energy option –preferred option, but: how large are the fluxes ? –  think as big as possible ! A. Roberts:

1978: 1.26 km³ 22,698 OMs 1980: 0.60 km³ 6,615 OMs 1982: km³ 756 OMs 1988: km³ 216 OMs DUMAND-II

Financial and technological reality !

DUMAND-II (The Octagon)  9 strings  216 OMs  100 diameter, 240 m height  Depth of bottom: 4.8 km  Lowest OM 100 m above bottom

or

Point sources, DUMAND-II (0.002 km³) expectations in the eighties !!! Note: in 1989, the only proven TeV  source was the Crab SNR! With these assumptions, a km³ detector would have discovered 5-50 (worst scenario) up to several ten thousand events (best scenario) per source

Diffuse sources, DUMAND-II (0.002 km³) expectations in the eighties

Technology boosts  Optical fibers with < 12 db attenuation over 40-km length and data rates of hundreds of MBaud (Nobel prize 2009!)  Appearance of 16“ Hamamatsu PMT  Appearance of 14“ „smart“ Philips PMT JOM Japanese Optical Module EOM European Optical Module

1987: The SPS  : a series of 14 cruises, with two lost strings  1987: success ! –depth-intensity curve –angular distributions –attenuation lenght (47  22 m) „Short Prototype String“

DUMAND after the SPS:  1989: HEPAP supports DUMAND-II  1990: DOE allocates funds for DUMAND-II  Further financial cuts  TRIAD (3 strings)  1993: shore cable laid  December 1993: deployment of first string and connection to junction box. Failure after several hours  1995: DUMAND project is terminated

Russia  Very active during early DUMAND workshops (Chudakov, Berezinsky, Bezrukov, Zhelesnykh, Petrukhin)  Kicked out of DUMAND after Russian Afghanistan invasion A. Roberts:  1980: Chudakov proposes exploration of Lake Baikal as possible site for a neutrino telescope  1981: start of site investigations at Lake Baikal (Domogatksy, Bezrukov)  Exploration of Atlantic, Black Sea, Indian Ocean, Pacific and Mediterranean sites (Zheleznyk, Petrukhin)  A. Roberts: „Communication among these groups is not very good“

The Lake BAIKAL experiment G. Domogatsky Bezrukov, Domogatsky, Berezinsky, Zatsepin  Largest fresh water reservoir in the world  Deepest Lake (1.7 km)  1981: first site explorations & R&D  Choosen site 3.6 km from shore, 1.3 km depth

Ice as a natural deployment platform

… and its mis-interpretation: A. Roberts:

Lake Baikal: the eighties  1984: first stationary string –Muon flux measurement  1986: second stationary string (Girlyanda 86) –Limits on GUT magnetic monopoles  All that with 15-cm flat-window PMT FEU-49  Development of a Russian smart phototube (Quasar)

Towards NT-200  1988: Germany joins  1989/90: design of NT-200  : NT channels at 3 strings -first underwater array -first 2 neutrino candidates  1995: NT channels at 4 strings  1996: NT channels at 4 strings -clear neutrinos  1998: NT channels at 8 strings 4-string stage (1996) J. Learned to C.Spiering: „Congratulations for winning the 3-string race!“ (NT-36 vs TRIAD vs AMANDA)

NT m 1366 m 2 PMTs in coincidence to surpress background

NT200 results  Atmospheric neutrinos  WIMP search  Diffuse neutrino fluxes  Skymap  GRB coincidences  Magnetic monopoles 396 candidates Amanda 4 years Baikal 5 years

NT200+ NT m 1366 m 140 m NT upgrade 2005/ times better sensitivity than NT200 for PeV cascades - basic cell for km3 scale detector construction For searches of diffuse neutrino fluxes, the small NT200 could compete with the much larger Amanda by monitoring a large volume below the detector. NT200+ fences this volume.

Gigaton Volume Detector, GVD  Sacrifice low energies (muon threshold ~ 10 TeV)  Protoype strings being tested  Modular clusters, stepwise installation > 2012  ~ 2000 optical modules (conventional PMs) 12 clusters of strings NT1000: top view R ~ 60 m L~ 350 m

All other deep water/ice detector projects started around 1990 or later. In the eighties /early nineties, shallow detectors have been proposed but never built. On the other hand, deep underground detectors reached their full blossom: - solar neutrinos - supernova neutrinos - limits on proton decay - first hints to neutrino oscillations - sky maps

Shallow detector projects  Advantages: easy access, less challenging environment  Disadvantages: huge background, not expandable  GRANDE –Shallow water, Lake, Arkansas, H. Sobel (Irvine)  LENA –Artificial water pool, Gran Sasso, M.Koshiba  SINGAO –Resistive Plate Chambers, Italy/UK  Swedish lakes –Early nineties, before Sweden joined Amanda

Underground Detectors  KGF  Baksan  FREJUS  Soudan  IMB  Kamiokande Superkamiokande  MACRO e.g. MACRO, 1356 upgoing muons ~ 1000 m²

Neutrino oscillations, proton decay  Deficit of solar neutrinos (see Kai Zuber‘s talk)  Deficit of atmospheric neutrinos as function of distance and energy  Stringent limits on proton life time |  m 2 32 | = (2.6±0.2) ·10 -3 eV 2 |  m 2 21 | = (8.3±0.3) ·10 -5 eV 2  12 = 33.9º±1.6º  23 = 45º±3º  13 < 9º

: revisiting the expectations  Underground detectors, 1000 m², only for young Supernovae in our Galaxy (Berezinsky)  New estimates on neutrinos from Supernova remnants and other galactic sources based on observations with Whipple and HEGRA  For supernova remnants, microquasars, extragalactic sources: need detector of order 1 km³.  The Waxman-Bahcall bound  The Mannheim-Protheroe bound  GRB as sources of cosmic rays and neutrinos

 bound WB bound MPR bound Diffuse Fluxes 2002 This model was down- corrected by a factor of 20 in 2005.

The ice option  1988: Pomerantz workshop, NSF Science and Technology Center for the South Pole (A. Westphal, T.Miller, D. Lowder, B. Price)  E. Zeller (Kansas) suggests to F. Halzen radiodetection of neutrinos in Antarctic ice  1989: attempt of Westphal and Lowder to measure ice transparency in existing boreholes  Jan. 89, ICRC, Adelaide: Decide to propose Amanda (B. Price, D. Lowder, S. Barwick, B. Morse, F. Halzen, A. Watson)  1990: Morse et al. deploy PMTs in Greenland ice F. Halzen

Nature Sept 91

South Pole  1991/91 first small PMTs deployed  Results consistent with 25 m absorption length Heaters and pumps to melt the holes

1 km 2 km 93/94 Catastrophal delay of light between strings 20 m away! (µsec instead of 100 nsec) 40 m

Explanation remnant bubbles which are disapppearing with increasing depth.

Amanda B4 1995: DESY and Stockholm build ~ 100 modules, 86 deployed in the season 95/96 at m depth The DESY crew

B4: first 2 neutrinos 

Drilling Hot water drilling

1 km 2 km IceCube will work ! 96/97 AMANDA - B m AMANDA B10

NATURE 2001

Skyplot of the very first 17 Nu candidates in B10 B10 skyplot published in Nature 2001

1 km 2 km 120 m  3 long strings  study deep and shallow ice for future IceCube 97/ Scattering coefficient (1/m) vs. depth

1 km 2 km AMANDA-II 99/ m Nearly horizontal 

Ocean Water

AMANDA results δ=90º 24h 0h Max Significance δ=54º, α=11.4h 3.38σ No significant excess found  Diffuse fluxes  Point sources  Neutrinos from GRB  WIMP searches  Magnetic Monopoles  Cosmic rays  SN monitoring  …. Skymap from 7years AMANDA: no significant excess

The one intriguing coincidence …. Year MayJuneJuly Flux of TeV photons (arb. units) WHIPPLE Arrival time of neutrinos from the direction of the AGN ES

05/06: 8 Remaining: 22 IceCube Strings 5 DeepCore Strings  complete in January 2011 IceCube Observatory

Shadow of the Moon Cosmic Rays  Absolute pointing  1°  Angular resolution  1° 0.5° 8 months IceCube 40 strings Downward muons, max. 28° above horizon, median energy of primary parent ~ 30 TeV

Large-scale anisotropy of downgoing muons IceCube (40 strings 2008) anisotropies on the per-mille scale (skymap in equatorial coordinates) h TeV 126 TeV

MILAGRO Compare to Northern hemisphere Tibet air shower array Simulation (Lallement et al. Science 2005)  Compton-Getting effect ?  Heliosphere effect ?  Nearby pulsar ?  Interstellar magnetic field ?  First observation on Southern hemi- sphere adds important piece of information.

First look above horizon (IceCube 2007, 22 strings) PeV-EeV range Southern hemisphere Northern hemisphere

Point Sources: The Progress factor 1000 in 15 years !

Another factor 1000 ! Diffuse Fluxes: The Progress Baikal/

Mediterannean projects NESTOR (since 1991) „Amanda-sized“-- under construction (?) ANTARES (since 1996) „Amanda sized“ -- data taking NEMO : R&D for km3 project Since 2003: km3 initiative KM3NeT

4100m 2400m 3400m ANTARES NEMO NESTOR

 1991: first site studies  1992: first muon count  : many ocean tests, build lab and infrastructure  2000: cable to site  2003: deploy first floor. Cable failure after a few weeks  Compare to 2000 declared plan: –deploy full tower 2003 –deploy 6 more towers 2005

ANTARES Installation: Junction Box - Dec 2002 Line 1 - March 2006 Line Dec 2007 Line May 2008

Antares results

NEMO R&D for KM3NeT - 4-floor tower in full tower end of 2009

KM3NeT

Recommendations KM3NeT  2001/02: High Energy Neutrino Astrophysics Panel –High physics interest –Need km³ scale –Need both hemispheres –No more than 1 Northern detector –Timely formation of Northern hemisphere deep water detector is encouraged  2008: ApPEC –The priority project for high energy neutrino astronomy is KM3NeT. –Encouraged by the significant technical progress of recent years, the support for working towards KM3NeT is confirmed. –Resources for a Mediterranean detector should be pooled into a single optimised design for a large research infrastructure, with installation starting in –The sensitivity of KM3NeT must substantially exceed that of all existing neutrino detectors including IceCube.

KM3NeT Mar 2012 Design decision Construction Data taking km  Site  Size  Configuration  Technology  Deployment

…a long march which has not yet reached its end.