Recent Results from the ANTARES experiment

Transcription

1 Recent Results from the ANTARES experiment Manuela Vecchi on behalf of the ANTARES Collaboration University of Roma La Sapienza and INFN ICATPP09- Como: October 6th 2009

2 Outline -astronomy: what, where, how and why? The ANTARES detector... Detection technique Antares facts & figures Detector operation First Physics Analysis Point Source Search Transient Source Search Indirect Dark Matter Search Multimessenger approach Conclusions 2

3 Neutrino Astronomy μ quasar Protons and photons are absorbed or deflected since they interact with matter/radiation. Neutrinos can travel unscattered opening a new window on the far Universe. Electrically neutral not bent by the magnetic fields Interacts very slightly escape from the dense areas of the Universe No absorption observation at cosmological distances Only weakly interacting particles low interaction cross section large detection volume is required Como, October 6th 09 Manuela Vecchi 3

4 Detection principle Neutrinos can interact in the medium surrounding the telescope. They can be detected using the visible C erenkov radiation produced as the high-energy charged lepton passes through the opaque medium. ANTARES 12 lines MC 3D PMT array Cherenkov light from μ 43 Sea bed μ μ interaction A deep underwater/ice detector is required to reduce the number of atmospheric s. 4

5 Detection principle Neutrinos can interact in the medium surrounding the telescope. They can be detected using the visible C erenkov radiation produced as the high-energy charged lepton passes through the opaque medium. Our GOALs: Search for production sites of HE neutrinos Understand production mechanisms of HE neutrinos Search for Dark Matter (WIMPs) Exotic particles... Sea bed μ μ interaction Cherenkov light from μ 3D PMT array 43 A deep underwater/ice detector is required to reduce the number of atmospheric s. 5

6 The ANTARES site Institut M. Pacha Electro-optical Cable of 40 km 6

7 The ANTARES detector 12 Lines 25 storeys / line 3 PMs / storey 885 PMs Buoy 14.5 m Floor 350 m 100 m Junction box ~60-75 m Depth : 2475 m Electrooptical Cable 7

8 Detector Milestones ~60 m MILOM: 17th Mar 2005 Line 1: 2nd Mar 2006 Line 2: 21st Sep 2006 Line 3, 4, 5: 29th Jan 2007 Line 6, 7, 8, 9, 10: 7th Dec 2007 Line 11, 12: 30th May

9 Optical Background 40 K Decay Continuous 30kHz background 40 K Bioluminescence 30kHz background, MHz outbursts K 20Ca + e + e Counting rate for 2 PMTs on line 1, as a function of time 9

10 Muon flux at the detector The data sample is dominated by the flux of atmospheric muons propagating downward through the detector. Atmospheric neutrinos contribute providing a flux that is 4-5 orders of magnitude less abundant than that of atmospheric muons atmospheric per year* Atmosphere 10 8 atmospheric μ per year* Sea Earth cosmic * Reconstructed tracks in 12 line detector 10

11 Track reconstruction Track reconstructed as upgoing through the detector, as seen in the online event display. Each box correnspond to 1 detection line. arxiv: v1 11

12 Track reconstruction Track reconstructed as upgoing through the detector, as seen in the online event display. Each box correnspond to 1 detection line. Depth Time arxiv: v1 12

13 5-lines data (2007) 2007 data μ triggers Total: 245 days Selected: 168 days Up Down Detected event are mainly due to downgoing atmospheric muons 13

14 5-lines data (2007) Neutrino candidate events: candidate events Data: 168 observed MC: 164±3(stat)±33(theor) ±16 (syst) 2007 data μ triggers Total: 245 days Selected: 168 days Up Down 14

15 Atmospheric muons studies Azimuth angle distribution data CORSIKA (QGSJET01) + NSU model MC uncert. Zenith Angle Distribution data CORSIKA (QGSJET01) + NSU model MC uncert. 5 lines data Systematic uncertainty due to uncertainties in the primary CR flux and hadronic models. No quality cut (QC) applied. data MUPAGE CORSIKA (QGSJET01) + NSU model CORSIKA (QGSJET01) + Horandel model 15

16 Point source search data Stringent cuts to ensure low background and good resolution. Search applied to 25 selected sources. All-sky search has also been performed. Blinding policy followed Two independent statistical methods used: BINNED and UNBINNED Selected sources for 2007 point source search 16

17 Point source search data Stringent cuts to ensure low background and good resolution. Search applied to 25 selected sources. All-sky search has also been performed. Blinding policy followed ANTARES 2007 skymap Two independent statistical methods used: BINNED and UNBINNED 5 line data - 94 candidate neutrino events selected in 168 active days. No significant excess has been found. Selected sources for 2007 point source search arxiv: v1 17

18 Point source search - Results Upper limits (90% c.l.), as a function of the declination, for the selected point-like sources. arxiv: v1 18

19 Search for transient sources Search for candidates in correlation with GRB alerts from satellites. The satellite triggered data taking efficiency during all alert message broadcasts from the GCN arxiv: v1 Whenever an alert is received, a dedicated data-taking is performed. The response time of the satellite triggered data taking in Antares to a satellite alert message. 19

20 Indirect dark matter search Cold Dark Matter Candidate: decays of neutralinos (WIMPs) gravitationally trapped in massive objects, i.e. the Sun, can produce HE s detectable by ANTARES. arxiv: v3 A search for s from neutralino annihilation in the Sun has been performed on 2007 data. Data sample 68.4 effective days No discovery 90% C.l. Upper limit msugra model predictions green : WMAP favoured relic density red : > WMAP favoured relic density blue : < WMAP favoured relic density 20

21 Indirect DM search (2) ANTARES 2007 data Upper limit to the flux of μ + anti μ from neutralino annihilation in the Sun, compared to other experiments, as a function of neutralino mass. ANTARES FULL DETECTOR Predicted measured flux of μ + anti μ from neutralino annihilation in the Sun, for the full ANTARES detector, after 5 years. 21

22 data 2007 (5 lines) : 168 d μ triggers 2008 ( 9 lines): 173 d μ triggers TOTAL 341 days lifetime. Up Down Single & multi-line fit events are shown. MC error band (theoretical + systematic) 30% μ MC error band (theoretical + systematic) 50% 22

23 data 2007 (5 lines) : 168 d μ triggers 2008 ( 9 lines): 173 d μ triggers TOTAL 341 days lifetime. Up Down candidate events All 2007/2008 silver runs ~ 1000 s MC error band (theoretical + systematic) 30% μ MC error band (theoretical + systematic) 50% 23

24 skymap 750 multilines neutrino candidates from 2007 and 2008, for 341 days of detector lifetime. ANTARES skymap (scrambled data) 24

25 Multimessenger approach Agreement with TAROT*: 2 optical telescopes at La Silla (CL) and Calern (FR) FOV: 1.86 x 1.86 Fast (~10s) re-positioning Optical follow-up of transient sources triggered by the ANTARES detector The trigger is satisfied when 2 evts are detected within = 3 x 3. * Télescopes à Action Rapide pour les Objets Transitoires arxiv: v2 Joint searches between gravitational-wave interferometers and ANTARES. arxiv: v1 Possible common sources (GRB-core collapse into BH; SGR powerful magnetars; hidden sources) Sky regions in common Expected low signals, coincidences increase chances of detection 25

26 Conclusions The ANTARES experiment is complete and taking data. First analyses on 2007 data show that the detector perfomance is well within expectactions. First upper limits to the flux of neutrinos from point-like sources have been set. First flux limits from hard and soft neutralino annihilation in the Sun have been set. Analysis of 2008 data is under way. Multimessenger approach is strongly pursued. detected 1000 neutrino candidates, a lot more science to come... 26

27 Backup slides 27

28 2007 data Results of 2 independent analysis Observed: 168 events MC: 164±3(stat)±33(theor) ±16 (syst) Observed: 185 events MC: 218±4(stat)±41(theor) (syst) 28

29 The trigger Front end chip digitizes charge and time of a light signal ALL DATA TO SHORE SCHEME: All data transmitted through multiplexed Gigabit links the whole data flow can not be written to disk μ Computer farm running a software trigger: look in all directions for light signals compatible with a muon track when found, write a Physics Event Other triggers exist: cluster of storeys,grbs, Galactic Center, 29

30 Expected performance Effective area N det =A eff Time Flux 30