Status and Perspectives of the BAIKAL-GVD Project Zh.-A. Dzhilkibaev, INR (Moscow), for the Baikal Collaboration for the Baikal Collaboration September 30 - October 3, 2014, Noto, Italy

GVD Next Generation IceCube HEX (+PINGU + …) KM3NeT (ORCA)

3 7 institutes ~55 scientists 7 institutes ~55 scientists baikalweb.jinr.ru Baikal GVD IIrkutsk U N-Novgorod Tech. U INR JINR MSU EvoLogics GmbH Germany St-Petersburg Marin Tech. U

Northern hemisphere – GC (~18h/day) and Galactic plane survey Location: 104 o 25’ E; 51 o 46’ N >250 km 3 fresh water

1350 m depth at ~ 3 km from shore

All connections on dry without bed junction boxes Underwater DAQ Center at shallow depth ~30 m

Infrastructure Shore station Lab Living quarters

Water properties allow detection of all flavor neutrinos with high direction-energy resolution! Moderately low background in fresh water: 15 – 40 kHz (10’’ R7081HQE) absence of high luminosity bursts from biology and K 40 background. Baikal, nm Absorption cross section, m -1 Scattering cross section, m -1 PMTs Counting rates April 2012 – February 2013 Absorption length – m Scattering length: m (L eff ~ m), Strongly anisotropic phase function: ~ 0.9

Gigaton Volume Detector (Lake Baikal) Optical module Section: basic detection unit GVD array 1 st GVD cluster: 8 strings - Installed strings and cable stations GVD4*GVD OMs Clusters (8 Strings) 1227 Sections (12 OMs) 2/Str.4/Str. Depths, m950 – – 1300 Instr. volume0.4 km km 3

Triggering and Data Transmission CLUSTER SECTION

GVD Performance Cascades: (E>10 TeV): V eff ~0.4 – 2.4 km 3 Muons: (E>1 TeV): S eff ~ 0.3 – 1.8 km OMs 2304 OMs OMs 2304 OMs Direction resolution o Direction resolution: 3.5 o o IC-target mass for cascades

GVD timeline 1 -pro  R&D and component prototype tests: 2008 – 2010  OMs, readout system, data transmission, calibration,..  Protoyping and engineering phase (1.cluster): 2011 – 2015  electro-optical shore cable, 3 x ½ strings, 3 full strings, 5 strings   1 cluster

Engineering array 2014 to shore DAQ 112 OMs at 8 Strings –2 Sections per String –12 OMs per Section DAQ-Center & Cable to Shore Acoustic Positioning System Instrumentation String with calibration and environment monitoring equipment Active depth 950 – 1300 m

Operation April – 27 September days Operation: 123 days Efficiency: 72.1% Total: 454 Runs Data : events Monitoring: events Cumulative number of events

Counting rates of OMs during April –September 2014 Amplitude distribution of selected OM recorded pulses Run 214 – 20 kHz Run kHz 1ph.el.= 8 codes Deep water light background at 1ph.el. level ! Operation

Performance of acoustic positioning system:  data every 30 seconds  high resolution Horizontal displacement of hydrophone Vertical displacement hydrophone at 430 m above the lake bed

Amplitude calibration LED1 Low Int. LED2 high Int. Calibration methods: 1 – two LEDs with high and low (10% OM detection probability) intensities 2 – analysis of noise pulses 1 ph.el. Code/charge 72 channels Code/ampl. 72 channels

Time calibration – two methods PMT signal delay = dt-dt 0 Measurement of signal delay of each channel Signal delay in cable (~90 m) is measured in lab. LED 15 m- distance between OMs dT 0 = 64.9 ns – expected time difference two LEDs dT reflected pulse Time difference of two channels dt Cable delay = dt/2 dt 0 =500 ns

Operation External calibration laser: -480 nm light pulses - Five fixed intensities: ~10 12 – 6   / pulse (~10 PeV – 600 PeV shower energy) - Distances: 50 – 250 m. Laser based light-source

Reconstruction of laser-light source position Laser and OMs coordinates from data of acoustic positioning system Time offsets of OMs from LED calibration Iterative reconstruction procedure – OMs with residual δt > 15 ns are excluded from analysis Multiplicity of rejected OMsMultiplicity of hit OMs after reconstruction

Distances between reconstructed and true laser position Reconstructed vertical laser coordinate Reconstruction accuracy (median value) of laser position ~3 m Accuracy of vertical coordinate about of 1.5 m

Reconstruction of laser-light source position reconstructed ~100 m

Prototype phase : First cluster „DUBNA“ String section, 12 OMs R ~ 60 m L~ 345 m  192 OMs at 8 Strings  2 Sections per String  12 OMs per Section  DAQ-Center  Cable to Shore  Acoustic Positioning System  Instrumentation String with detector calibration and environment monitoring equipment  Active depth 950 – 1300 m

Cluster performance for cascades detection Reconstruction of a cascade vertex: Iterative procedure- OMs with residual δt > 15 ns are excluded and final N hit is obtained for following analysis. δr = |r rec – r gen | ~ 2 m (median value) Distance between generated and reconstructed vertices Energy resolution for cascades: δE/E ~ 30%, averaged by E -2 e spectrum Averaged by E -2 e spectrum Averaged by E -2 e spectrum N hit > 10

Directional resolution for cascades: Median value of mismatch angles ~ 3 °- 4° depending on energy and cuts Distribution of mismatch angles Cumulative distribution N hit > 10

Neutrino Effective Area GVD-Cluster: Events per Year from IC-flux (E 2 F IC =3.6·10 -8 GeV cm -2 s -1 sr -1 ) ~1 Event/Year (>100 TeV) Cut on number of hit OMs after vertex reconstruction significantly suppresses background atm. neutrinos Applied cuts: N hit > 20; E rec > 100 TeV

Atmospheric muons MC-sample corresponding to 341 life days Hit channel multiplicity distributions 1 – after vertex reconstruction 2 – after vertex reconstruction quality cuts 1 2 Vertex reconstruction filter: -270< z rec <200 m, (OMs location:  m)

Expected number of events for 1 year exposition: 1 ev. from astrophysical IC flux 0.05 ev – atm. ; 0.05 ev. – atm. μ Sensitivity on one flavor E -2 flux (preliminary, without systematics)

GVD timeline 2 -pro Cumulative number of clusters vs. year Year baseline Compressed baseline

Conclusion: During the key elements and systems of the GVD have been developed, produced and tested in Lake Baikal. Scientific-Technical Report (STR) has been prepared Prototyping & Construction Phase of Project was started in 2011 and will be concluded in 2015 with deployment in Lake Baikal of the first Cluster of BAIKAL-GVD. Since April 2014 the five string engineering array comprising total of 112 OMs is operating in Lake Baikal  Deployment of the first stage of GVD with about of 0.4 km 3 effective volume for cascade detection is expected in