32 International Cosmic Ray Conference The BAIKAL-GVD

32 International Cosmic Ray Conference The BAIKAL-GVD project of a km 3 -scale neutrino telescope in Lake Baikal Vladimir Aynutdinov for the Baikal Collaboration Beijing, 17 August, 2011 1

Collaboration A. V. Avrorin 1, V. M. Aynutdinov 1, I. A. Belolaptikov 3, D. Yu. Bogorodsky 2, V. B. Brudanin 3, N. M. Budnev 2, I. A. Danilchenko 1, G. V. Domogatsky 1, A. A. Doroshenko 1, A. N. Dyachok 2, Zh. -A. M. Dzhilkibaev 1, S. V. Fialkovsky 5, O. N. Gaponenko 1, K. V. Golubkov 3, O. A. Gress 2, T. I. Gress 2, O. G. Grishin 2, A. M. Klabukov 1, A. I. Klimov 8, K. V. Konishchev 3, A. V. Korobchenko 2, A. P. Koshechkin 1, F. K. Koshel 1, V. A. Kozhin 4, V. F. Kulepov 5, D. A. Kuleshov 1, L. A. Kuzmichev 4, V. I. Ljashuk 1, S. P. Mikheevj , M. B. Milenin 5, R. A. Mirgazov 2, E. R. Osipova 4, A. I. Panfilov 1, A. L. Pan’kov 2, L. V. Pan’kov 2, A. A. Perevalov 2, D. A. Petukhov 1, E. N. Pliskovsky 3, V. A. Poleshchuk 2, E. G. Popova 4, M. I. Rozanov 7, V. F. Rubzov 2, E. V. Rjabov 2, A. V. Shirokov 4, B. A. Shoibonov 3, A. A. Sheifler 3, A. V. Skurikhin 4, Ch. Spiering 6, O. V. Suvorova 1, B. A. Tarashchansky 2, A. S. Yagunov 2, A. V. Zagorodnikov 2, V. A. Zhukov 1 , and V. L. Zurbanov 2 1 Institute for Nuclear Research, Moscow, 117312 Russia 2 Irkutsk State University, Irkutsk, 664003 Russia 3 Joint Institute for Nuclear Research, Dubna, 141980 Russia 4 Institute of Nuclear Physics, Moscow State University, Moscow, 119991 Russia 5 Nizhni Novgorod State Technical University, Nizhni Novgorod, 603950 Russia 6 DESY, Zeuthen D-15738, Germany 7 St. Petersburg State Marine Technical University, St. Petersburg, 190008 Russia 8 Russian Research Center Kurchatov Institute, Moscow, 123182 Russia 2

OUTLINE 1. Introduction 2. Baikal Neutrino Experiment - overview 3. Future Gigaton Volume Detector in Lake Baikal (BAIKAL-GVD ) - GVD technical design - Prototype GVD string: 2009 -2010 - Prototype GVD cluster: 2011 4. Plans 5. Summary 3

NEUTRINO TELESCOPES NT 200+ ANTARES KM 3 Ne. T A 12 strings, 885 OM N N 11 strings, 228 OM Baikal-GVD project Ice. Cube 96 strings, 2304 OM Ice. Top: 81 stations Ice. Cube array: 86 strings, 5160 OM 4

Baikal Scattering cross section, m-1 The BAIKAL Site Absorption cross section, m-1 Lake Baikal, Siberia , nm Baikal water properties: Abs. Length: 22 ± 2 m Scatt. Length: 30 -50 m 1370 m maximum depth. • Distance to shore ~4 km • No high luminosity bursts from biology. • Deployment simplicity (ice as a deployment platform). Shore cable mounting Deployment 5

Status of Baikal experiment NT 200+ is operating now in Baikal lake Central part - NT 200 8 strings (192 optical modules ) Height x = 70 m x 40 m, Vinst=105 m 3 Effective area: 1 Te. V~2000 m² Eff. shower volume: 10 Te. V~ 0. 2 Mton NT 200+ = NT 200 + 3 outer strings 228 optical modules Height x = 210 m x 200 m, Vinst = 4 106 m 3 Eff. shower volume: 104 Te. V ~ 10 Mton ~ 3. 6 km to shore, 1070 m depth The Baikal collaboration follows since several years a R&D program for a kilometer-scale Gigaton Volume Detector in Lake Baikal (BAIKAL-GVD). The main scientific goal of GVD is to map the high-energy neutrino sky in the Southern Hemisphere including the region of the galactic centre. 6

BAIKAL-GVD Layout 12 clusters of strings 96 Strings × 24 OM String: 2 Sections × 12 OM Clusters 8 strings 2304 Optical Modules Optimization Hardware trigger: coincidences of nearby OM (threshold 0. 5&3 p. e. ). Software selection: muons – 6 triggered channels at 3 strings; cascades – 4 channels at 3 strings. String section, 12 OM Trigger conditions L~ 350 m 1 km Basic simulation parameters: Z - the vertical distance between OMs R - the distance between strings and cluster center H - the distance between cluster centers. An optimum for cascade detection volume and muon effective area: H=300 m, R=60 m, and Z=15 m Eff. cascade volume (trigger level): Veff ~0. 3– 0. 8 km 3 , δ(lg. E) ~0. 1, θmed~ 3 o- 7 o (E>50 Te. V) Eff. muon area (trigger level): R ~ 60 m Seff ~ 0. 2 – 0. 5 km 2, θmed~ 0. 5 o- 1 o (E: 10 Te. V - 1 Pe. V) 7

String section – low level DAQ unit Optical Module Glass pressure sphere VITROVEX (17”) OM electronics: Amplifier, HV DC-DC, OM controller 2 on-board LED flashers: 1… 108 pe. , 430 nm, 5 ns Mu-metal grid PMT R 7081 HQE : D=10”, ~0. 35 QE Elastic gel Section: 12 Optical Modules & Central Module 3 ADC boards: 12 FADC channels, 200 MHz 1 OM slow-control board - Data communication between OM and CM via an underwater RS-485 bus - OM power control. 1 Master board - Trigger logic - Data readout from ADC boards - Connection via local Ethernet to the cluster DAQ center (DSL-modem, 1. 2 km cable, 8 Mb). 8

BAIKAL-GVD prototype strings: in-situ tests 2009, 2010 2009 2010 Time parameter estimations Tests with LED flasher produces pairs of delayed pulses. Light pulses are transmitted to each optical module (channel) via individual optical fibers. Time between pulses d. T are calculated from the waveform data. OM#1 OM#2 Time resolution: (d. T) = 1. 6 ns OM#3 Tests with LASER T = <d. TEXPECTED – d. TLASER > d. TEXPECTED = (r 2 -r 1) cwater d. TLASER - time difference between two channels measured for Laser pulses. XP 1807 R 8055 R 7081 HQE R 8055 OM#4 OM#6 OM#7 OM#8 r 1 Time error: T ~ 2 ns LASER r 2 110 m OM#5 OM#9 OM#10 OM#11 OM#12 97 m 9

BAIKAL-GVD prototype cluster: 2011 Sketch of prototype cluster, neutrino telescope NT 200+, and communication lines locations. In April 2011, a prototype cluster of GVD has been installed near NT 200+ and commissioned in Lake Baikal. The cluster consists of 3 vertical strings with 8 optical modules each, deployed at depths between 1205 m and 1275 m. The vertical spacing between OMs is 10 m and the horizontal distance between strings is about of 40 m 10

Cluster technical design Optical modules The OMs house photomultipliers of different types: 16 PMT R 7081 HQE (Hamamatsu 10”) 5 PMT R 8055 (Hamamatsu 13”) 3 PMT XP 1807 (Photonis 12”) Strings • 8 optical modules • Central module (CM) with 8 FADC channel: 200 MHz, 12 bit. • Service module (SM): OM power supply. • 3 modules of acoustic positioning system - 2 cm resolution Cluster DAQ center provides the string triggering, power supply, and communication to shore. Communication lines Connection between the strings and cluster DAQ center: 1. 2 km carrier cable. Connection to shore – optical cable 6 km. 11

Cluster DAQ center GASIK CC Adjunction Box Shore optical cable 6 km length 3 pairs of optical fibers 3 copper lines РС Block diagram of the cluster DAQ center Data from 3 strings are transferred through 8 Mbit DSL-modem to the cluster DAQ center. 3 DSL-modems are installed in PC-module. DAQ center is connected to shore by two optical 1 Gbit Ethernet lines. Optical converters and power units are installed in Adjunction box. Communication Center (CC) provides global trigger and string power supply. 12

Plans Final technical design: 2011 -2012. Full scale GVD string with 24 OM Preproduction: 2012– 2013(14). Full scale GVD cluster, 8 strings (192 OMs). Production (preliminary) Cost estimation 25 MEuro Ø 2014– 2015: Effective volume 0. 1 – 0. 3 km 3 Ø 2016– 2017: Effective volume 0. 3 – 0. 6 km 3 Ø 2017– 2018: Effective volume 0. 6 – 0. 9 km 3 13

Summary 1. Neutrino telescope NT 200 is working in Lake Baikal for more than 10 years. 2. Preparation towards a km 3 -scale Gigaton Volume Detector in Lake Baikal is currently a central activity: - In-situ tests of the prototype string shows good performance of all string elements (2009 -2010). - A prototype GVD cluster with 3 strings was installed (2011) - New technology shore cable with optic channels was mounted (2011). 3. GVD Technical Design Report was prepared (2011) 4. Full scale GVD cluster (~200 OMs) is expected at 2013(14). 14

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