Moscow, V. Aynutdinov, INR RAS for Baikal collaboration The Baikal neutrino telescope: The Baikal neutrino telescope: Physics results and future plans Physics results and future plans

  Institute for Nuclear Research, Moscow, Russia.   Irkutsk State University, Russia.   Skobeltsyn Institute of Nuclear Physics MSU, Moscow, Russia.   DESY-Zeuthen, Zeuthen, Germany.   Joint Institute for Nuclear Research, Dubna, Russia.   Nizhny Novgorod State Technical University, Russia.   St.Petersburg State Marine University, Russia.   Kurchatov Institute, Moscow, Russia. Collaboration BAIKAL in BAIKAL in CernCourier 7/8-2005

A Amanda/IceCube Baikal N N Neutrino telescope NT200 (1998) Design Physics Results (selected) : NT200 upgrade -> NT200+ (2005) New Design Calibration (new laser) Perspectives: Gton scale detector (GVD) at Baikal NT200+ as a basic cell of future Gton detector Summary Motivation Present telescope configuration is perfect test facility for future Gton detector Outline:

Shore station 4000 m 1366 m The Site 1070 m depth Absorption length: m Scattering length: m Ice as a natural deployment platform 51 d 45’’ 59’ N 104 d 25’ 09’’ E

Ice as a natural deployment platform Ice stable for 6-8 weeks/year: – –Maintenance & upgrades – –Test & installation of new equipment

Baikal Abs. Length: 22 ± 2 m Scatt. Length (geom) ~ m  cos  ~ Baikal - Optical Properties Open configuration of the Telescope and good water parameters of Baikal water allow to observe big water volume much more than geometrical boundaries allow to observe big water volume much more than geometrical boundaries

Example of interaction between ANTARES,NEMO   Baikal  Verification of Lake Baikal Attenuation / Absorb. / Scatt. results   Cross-Calibration: AC9 (Antares/Nemo) vs. Burhan ASP15 Baikal-NEMO Campaign March, 2001 see: NIM A498 (2003)

1998: NT OM at 8 strings 1 Mton at 1 PeV 1996 NT96 96 OM at 4strings 2005: NT OM at strings 10 Mton at 10 PeV Project Milestones 1991 Project NT200 approved 1993 NT36 36 OM at 3 strings The first underwater array operates First  ’s and ’s in Neutrino Telescope

-8 strings: 72m height optical modules  96 measuring channels  T, Q measure *Timing ~ 1 nsec *Dyn. Range ~ 1000 pe Effective area: 1 TeV ~2000 m² Eff. shower volume: 10TeV ~0.2Mt Quasar PMT: d = 37cm Height x  = 70m x 40m, V geo =10 5 m 3 = 0.1Mton

Selected Results NT200 Low energy phenomena (muons) - Atmospheric neutrinos - WIMP neutrinos High energy phenomena (cascades) Diffuse neutrino flux - Diffuse neutrino flux - Neutrinos from GRB - Prompt muons and neutrinos - Exotic HE muons Search for exotic particles - Magnetic monopoles

Atmospheric Neutrinos 372 Neutrinos in 1038 Days ( ) Skyplot (equatorial coordinates) of neutrino events E THR GeV Important calibration tool

WIMP Search  +   b + b C +  +  Search of nearly vertically upward going muons, exceeding the flux of atmospheric neutrinos Limits on the excess muon flux from the centre of the Earth as a function of WIMP mass centre of the Earth as a function of WIMP mass Angular distribution of selected neutrino Angular distribution of selected neutrino candidates as well as background expectation

Physics topics: - - HE cascades from e   - NC/CC * Diffuse astroph.flux * GRB correlated flux - - HE atmospheric muons * Prompt  * Exotic  NT-200 is used to watch the volume below for cascades.  („BG“) NT-200 large effective volume Search for High Energy Cascades Look for upward moving light fronts. Signal: isolated cascades from neutrino interactions Background : Bremsshowers from h.e. downward muons Final rejection of background by „energy cut“ (Nhit)

t min > -10ns N hit > 15 ch. Hit channel multiplicity (experiment and background expectation) Diffuse Neutrino Flux  atm 2.5  Shape of signal in Nhit distribution for  = A E -  (  =1.5, 2.0, 2.5). NT200 (1038 days) DIFFUSE NEUTRINO FLUX (Ф ~ E -2, 10 TeV < E < 10 4 TeV) e      (AGN) e      (Earth) ) Ф ( e  )   <8.1 ·10 -7 GeV cm -2 s -1 sr -1 W-RESONANCE ( e ) ( E = 6.3 PeV,  5.3 · cm 2 ) Ф e < 3.3 · (cm 2 · s · sr · GeV ) -1 ~

Experimental limits + bounds/ predictions Models already ruled out by the experiments SS - Stecker, Salamon96 (Quasar) SeSi - Semikoz, Sigl (Models/Expts. are rescaled for 3 flavours) Diffuse Flux Limits + Models

New configuration NT m 100m 36 additional PMTs on 3 far ‘strings‘  4 times better sensitivity  Improve cascade reconstruction Vgeom ~ 4 · 10 6 m 3 Eff. shower volume: 10 4 TeV ~ 10 Mton Expected -sensitivity (3 yrs NT200+) : E 2 Ф V < 0.9 · GeV cm -2 s -1 sr -1 NT200+ as test facility for Gton scale detector 1. Optical module 2. Calibration system 3. New electronics 4. Data acquisition system 5. Time synchronization 6. Cable communications

NT200+ commisioned April outer strings were instaled 2. New DAQ – final modernization - 2 Underwater PC with Flex DSL modem (1 Mbod), - 2 Underwater PC with Flex DSL modem (1 Mbod), Underwater Ethernet Underwater Ethernet - Synchronization system - Synchronization system * time synchronization * time synchronization NT200 outer strings NT200 outer strings * event clusterisation * event clusterisation 3. New Software DOS -> Linux, Remote control DOS -> Linux, Remote control 4. New 2 cables to shore (2x4 km) 5. Calibration - New bright Laser

DAQ and control system of NT200+ Two subsystems: NT200 and NT+ Two-level time measurement and data acquisition systems: Low level: - Strings: PMT time and amplitude measurements; - DEM: trigger and event clusterisation systems - SEM: slow control DAQ Center - 2 underwater PC connected to shore; - CEM: trigger time measurement

PC104: Advantech-PCM9340 DSL-M: DSL-modem FlexDSL-PAM-SAN with hub and router, 2 Mbit/s. SwRSTP: a managed Ethernet switch RS2-4R CSrv: WUT-58211, for PC-terminal emulation Mc: two media-converters for coaxial connection D-Mod, C-Mod: experiment data and control modems Underwater PCs

New Laser 100m X2 X1 X3 100m  Laser is visible >200m with high Ampl. (NT and ext.strings) Laser intensity : cascade energy: (10 12 – )  : (10 – 500) PeV RMS of arrival time distribution: ~ 2 ns

t1t1t1t1 t2t2t2t2 t 12 5 series of Laser pulses NT200+ time resolution  t = t 1 + t 12 – t 2  t 1,  t 2 - PMT jitter and light scattering  t 12 )  2 ns - electronics jitter Light scattering - scattering length 30 m - distance to Laser ~200 m Jitter of electonics ~2 ns Jitter of electonics ~2 ns - synchro cable length 1.2 km - TDC bin 2 ns The amplitude dependence of relative time jitter measured for several pairs of channels of NT200 and external string. Red line is result of calculations

Reconstructed vs. simulated coordinates of cascades in NT200+ (blue) and NT200 (red) NT200 (red) NT200+ efficiency of cascade reconstruction Laser coordinates reconstruction NT200 NT extern. str.  r < 1 m

NT200+ as a subunit of a Gton scale detector For High Energy Cascades: A single string replacing the NT200 central core reduces V eff less than x3 for E>100TeV.  12 OMs strings as a subunit for a Gton scale detector = ok. Effective volume with

A future Gigaton (km3) Detector in Lake Baikal. Sparse instrumentation: 91 strings with 12/16 OM = 1308 OMs (NT200 = 192 OMs)  effective volume for 100 TeV cascades ~ km³  muon threshold between 10 and 100 TeV

Gton detector at Baikal lake 1. Optical module: PMT selection 2. Detector configuration: PMT location, string configuration, distances, … 3. Electronics: flash ADC, trigger conditions, … 4. Communications: optical cables, connectors, … 5. Data acquisition system, time synchronization R&D on the basis of NT-200+ configuration

CONCLUSION 1. BAIKAL lake experiment 1. BAIKAL lake experiment running since 12 years - Diffuse Neutrino flux limit - Limit on an excess flux due to WIMP annihilation in the Earth - Limit on the flux of fast magnetic monopoles 2. NEW configuration NT200+ start of operation April NT200+ is tailored for diffuse cosmic neutrinos Veff ~ 10 Mton at 10PeV Expected -sensitivity (3 yrs NT200+) : E 2 Ф v < GeV cm -2 s -1 sr -1 - NT200+ gives good possibilities to optimise the structure and to investigate the basic elements of future Gton scale detector R&D Gigaton Volume Detector (km3) at Baikal lake was started

Relativistic magnetic Monopole Cherenkov-Light n 2 ·(g/e) 2 n = 1.33 (g/e) = 137 / Flux upper limit (cm -2 s -1 sr -1 )

NT200+ Start of operation April Apr - 23 May Exposition time: 640 hours - - Events number : 7.6  More than 1 outer string: 20 events Examples of events

NT200+ Start of operation April Apr - 23 May Exposition time: 640 hours - - Events number : 7.6  More than 1 outer string: 20 events Examples of events

New Laser: Design Isotropizer: - Glass bulb filled with “MicroGlassSpheres” (S32 from 3M; 20-70um dia.) mixed with OpticalGel  A “LaserBall” similar to the SNO calibration device. - Total loss is low: 12% - 25% only ! calibrated with “Ulbricht Sphere” (1.5m diam.) Absolute Laser–Calibration (with commercial Laser-PowerMeter) to optimize yield also at the lake (monitor laser vs. years) Expect >10^12 photons/pulse