The Baikal Experiment - Status, Results and Perspectives Zh. Dzhilkibaev for the Baikal Collaboration. - презентация

1 The Baikal Experiment - Status, Results and Perspectives Zh. Dzhilkibaev for the Baikal Collaboration

2 1.Institute for Nuclear Research, Moscow, Russia. 2.Irkutsk State University, Irkutsk, Russia. 3.Skobeltsyn Institute of Nuclear Physics MSU, Moscow, Russia. 4.DESY-Zeuthen, Zeuthen, Germany. 5.Joint Institute for Nuclear Research, Dubna, Russia. 6.Nizhny Novgorod State Technical University, Nizhny Novgorod, Russia. 1. St.Petersburg State Marine University, St.Petersburg, Russia. 2. Kurchatov Institute, Moscow, Russia. The Baikal Collaboration

3 Nowadays operating neutrino telescopes: Baikal (NT-200) - Lake Baikal AMANDA II - South Pole Optical properties Deep underwater/underice particle detection Optical Module sensitivity (Baikal experiment) M.Markov: neutrino detection in natural transparent media (lakes, ocean, ice): - huge size (up to km 3 scale) detectors (AMANDA II ~ 1.5 Mton) - given optical parameters of medium, detection volume/area depends on cascades/muons energy (Baikal (NT-200) ~ ( ) Mton for ( ) Gev cascades energies) Cherenkov radiation intensity F (L) ~ I (E) exp(-L/L at ) I ~ 0.6 E /TeV, I ~ 10 8 E sh /TeV (60 m from

4 The Baikal Telescope NT-200 -NT-200 location and design -Selected results -NT-200+ status -Conclusion

5

6 The Site 4 cables x 4km to shore. 1070m depth 3600 m 1366 m NT-200

7 Ice as a natural deployment platform Ice stable for 6-8 weeks/year: –Maintenance & upgrades –Test & installation of new equipment –Operation of surface detectors (EAS, acoustics,… ) Winches used for deployment operations

8 Baikal Abs. Length: 22 ± 2 m Scatt. Length (geom) ~ m cos ~ Baikal - Optical Properties In-situ measurements FreshWater no K40 BG

9 9 The NT-200 Telescope -8 strings: 72m height optical modules - pairwise coincidence 96 space points - calibration with N-lasers - 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=10 5 m 3

10 Few upward pointing pairs get hats against sedimentation Optical Module – Pair (Coincidence)

11 Atmospheric muon flux as a calibration source Time difference distributions t = t 52 -t 53 ) MC Experiment t, ns MC Experiment Ph.el. Amplitude distributions (ch.12)

12 Selected Results - Low energy phenomena atmospheric neutrinos neutrino signal from WIMP annihilation - Search for exotic particles magnetic monopoles - High energy phenomena neutrinos from GRB prompt muons and neutrinos diffuse neutrino flux

13 13 Atmospheric Muon-Neutrinos Thresh. ~ 15 GeV Skyplot (galactic coordinates) ~ 3° 3-dimensional reconstruction 84 events BG dominated bin

14 14 WIMP Neutrinos from the Center of the Earth + b + b W + + W - C + + Detection area of NT-200 for vertically up-going muons detection (after all cuts)

15 Neutrino induced muons E thr = 10 GeV Atmospheric neutrinos (Bartol-96 flux, oscillations - SK, K2K) WIMP Search

16 Applied cuts efficiency - experiment - atm. muons (expectation) - neutrinos (with oscillations) - neutrinos (without oscillations) WIMP Search

17 atm. neutrino flux - Bartol events - experiment 36.6 events - expected without oscillations 29.7 events - expected with oscillations Angular distributions (502 days, NT-200) atm. neutrino flux - Bartol-96 F Honda et al. - 04) = 0.7 F Bartol-96) no osc. osc.

18 Excess neutrino induced upward muon flux 90% c.l. limits from the Earth ( 502 days of NT-200 livetime, E > 10 GeV ) WIMP Search

19 Search for fast monopoles ( 780 livedays Monopole limit (90% C.L.) N = n 2 (g/e) 2 N = 8300 N g = 137/2, n = 1.33 Event selection criteria: hit channel multiplicity - N hi t > 35 ch, upward-going monopole - (z i -z)(t i -t)/( t z ) > 0.45 & o Background - atmospheric muons N hit distributions

20 Search for slow massive monopoles (10 -5 < -3 cat M+p M+e + (+ …), ~10 5 NT detection of massive bright objects (GUT-monopoles, nuclearites, Q-balls …) monopole trigger: N hit >4 within dt=500 sec selection requirements - N ch >1 with N hit >14 MACRO 150 days life time

21 21 Search for High Energy - Cascades NT-200 large effective volume 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 (N channel ) (BG)

22 High energy cascade selection: t min = min(t i - t j ), j > i - cascades below NT-200 N hit > 15 ch. - hit channel multiplicity Data (N hit >40 ch.) Data (t min >-10 нс)

23 Hit channel multiplicity (experiment) AE - hit channel multiplicity cut atm cut

24 Search for neutrinos correlated to Gamma Ray Bursts Data consistent with expected background from atm. muons 90% C.L. limits on neutrino flux from GRBs: N hit >34 1 selected event, N bg =0.47 F(E)=A tot E-E 0 ), A tot =N 90 /S(E 0 ) A GRB = A tot /N tot April February 2001: N tot = 722 BATSE events NT-200: N hit >10 & t min >-10 ns & t BATSE -100 ns < t < t BATSE +100 ns

25 Event selection criteria High energy cascades - experiment - atm. muons background

26 Prompt atmospheric muons and neutrinos ( source of background for neutrino telescopes ) Neutrinos - e : cascades (CC, NC) E -2.6, EE b = GeV Muons: cascades (e + e -, brem, ph.-nucl.) E -2.6 Predictions: ZHV - E.Zas, F.Halzen, R.Vazquez-93 RVS - O.Ryazhskaya, L.Volkova, O.Saavedra-02 QGSM, RQPM - E.Bugaev et al.-89 TIG - M.Thunman, G.Ingelman, P.Gondolo-96 GGV - G.Gelmini, P.Gondolo, G.Varieschi-02 (hep-ph/ ) Sources - decays of short-lived particles ( D, …) isotropic for E < 10 7 GeV 90% c.l. limits for prompt and e fluxes (780 life days)

27 The 90% C.L. Limits Obtained With NT-200 (780 days) DIFFUSE NEUTRINO FLUX (Ф ~ E -2, 10 TeV < E < 10 4 TeV) e = (AGN) e = (Earth) Diffuse flux of e,, : cascades W-RESONANCE ( E = 6.3 PeV, 5.3 · cm 2 ) Ф e < 4.2 · (cm 2 · s · sr · GeV ) -1 Ф e < 5.0 · (cm 2 · s · sr · GeV ) -1 (AMANDA04) E 2 Ф < 1.0 ·10 -6 GeV cm -2 s -1 sr -1 E 2 Ф < 8.6 ·10 -7 GeV cm -2 s -1 sr -1 (AMANDA04) V g (NT-200) AMANDA II

28 Diffuse flux of e,, : cascades Experimental limits and theoretical predictions SS SP SDSS D.Semikoz, G.Sigl 04 Models ruled out by AMANDA04 SDSS - Stecker et al.92 SS - Stecker, Salamon96 SP - Szabo, Protheroe92 MPR MPR - Mannheim, Protheroe, Rachen

29 Upgrade to NT : two distant test string 2005: completion 36 additional PMTs on 3 far strings 4 times better sensitivity ! PeV Mton

30 Cascade coordinates (energy) reconstruction efficiency NT

31 NT-200+ status 2004: - new cable to shore - DAQ system has been improved - two of three outer strings are installed common events are taken during 364 hours life time (0.017 Hz)

32 NT as subunit for a Gton scale detector NT

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

34 CONCLUSION - successfully running since 10 years - strong in HE-diffuse search (shower) and exotic particles (monopoles): Mton detector - good GRB-sensitivity, complementary to AMANDA - relevant other results: WIMP - upgrade to NT-200+ in R&D Gigaton Volume Detector (km3)

35 year anniversary celebration

36 Экспериментальный материал Гамма-всплески (эксперимент BATSE) Декабрь предварительные результаты Основные параметры GRB - время регистрации - длительность - направление на вспышку - энергия вспышки Темп регистрации ~ 1 событие/день Основной каталог BATSE (triggered GRB) Каталог Штерна (non-triggered GRB) ~ 80% Данные с 1991 по 2000 год BATSE GRB Final Sky Map T_90

37 Экспериментальный материал Cобытия NT-200 Декабрь предварительные результаты Основные параметры событий Т - время регистрации М - множественность триггированных ОМ (характеризует энергию ливня) t - разность времен срабатываний ОМ (характеризует направление прихода) Критерии отбора событий M > 10 OM t < 10 ns Эффективно отбираются горизонтальные ливни и ливни из нижней полусферы Темп регистрации - ~10 -2 с Данные апрель февраль 2000

38 Поиск временных корреляций Декабрь предварительные результаты Статистика экспериментальных данных В анализируемый период апрель февраль 2000 c периодом чувствительности NT-200 совпало 386 GRB по основному каталогу BATSE и 336 по каталогу Штерна (>1 часа непрерывной экспозиции в области GRB). Количество GRB из основного каталога BATSE (B) и каталога Штерна (S) Up, Down – GRB из верхней и нижней полусферы

39 Поиск временных корреляций Декабрь предварительные результаты Поиск коррелированных во времени событий в области GRB Оценивалось количество событий в интервалах dt = 1, 2,... 5 секунд в области GRB (поиск кластеров событий с множественностью К)

40 Поиск временных корреляций Декабрь предварительные результаты Анализ корреляций для различных порогов регистрации Оценивалось суммарное количество событий для всех GRB при различных множественностях М

41 Предел на поток нейтриино Декабрь предварительные результаты Sef N 90 - верхний 90% предел на количество событий S - эффективная площадь - нормированный поток нейтрино