1. Kay Graf University of Erlangen for the ANTARES Collaboration 13th Lomonosov Conference on Elementary Particle Physics Moscow, August 23 – 29, 2007 Acoustic Particle Detection and the ANTARES Neutrino Telescope Topics: -Astroparticle Physics with Neutrinos -ANTARES Neutrino Telescope -Acoustic Detection of Neutrinos

2. 13th Lomonosov Conference Kay GrafUniversity of Erlangen August 23 – 29, 2007 2 Astroparticle Physics with (U)HE Neutrinos Low-energy limit: detector sensitivity background High-energy limit: neutrino flux decreases like E –n (n ≈ 2) large detection volume needed optical Cherenkov telescopes: Baikal, IceCube, ANTARES, … new techniques: radio, acoustics, … (many experiments) …

3. 13th Lomonosov Conference Kay GrafUniversity of Erlangen August 23 – 29, 2007 3 Two (U)HE Detection Methods optical Cherenkov cone photosensor array   acoustic pressure waves hydrophone array cascade Optical Cherenkov detector 3D array of photosensors attenuation lengths of order 50m to 100m (blue light) medium: water, ice Acoustic detector 3D array of hydrophones very long attenuation lengths (of order 1km) medium: water, ice and salt established technology feasibility studies

4. 13th Lomonosov Conference Kay GrafUniversity of Erlangen August 23 – 29, 2007 4 14.5m 100 m 25 storeys, 350 m Junction Box ~70 m The ANTARES Neutrino Telescope string-based detector (Lines) ¼ 0.1 km 2 geometric area downward-looking photomultipliers (PMs), axis at 45 O to vertical 2400 m water depth 25 km off shore ANTARES site F I E

5. 13th Lomonosov Conference Kay GrafUniversity of Erlangen August 23 – 29, 2007 5 Current Status and Plans Full detector: 12 Lines with 900 PMs 1 Instrumentation Line (IL) for environment monitoring Running: 5 Lines (375 PMs) + Installed: 4 Lines + IL, to be connected this year Completion: Early in 2008 Acoustic setup: 6 storeys (36 sensors)

6. 13th Lomonosov Conference Kay GrafUniversity of Erlangen August 23 – 29, 2007 6 Muon Event in the Optical Detector hit pattern depending on zenith angle and distance from string hit time (ns) hit altitude z (m) middle of the detector first triggered hit Line 1 

7. 13th Lomonosov Conference Kay GrafUniversity of Erlangen August 23 – 29, 2007 7 hit time hit altitude hit time hit altitude Selected Events: Muon Bundle

8. 13th Lomonosov Conference Kay GrafUniversity of Erlangen August 23 – 29, 2007 8 Line 1Line 2 Line 4 Line 3 Line 5 hit time hit altitude hit time hit altitude Selected Events: Neutrino Candidate triggered hits on three Lines zenith angle: θ = 35° -700 400 1500 ns

9. 13th Lomonosov Conference Kay GrafUniversity of Erlangen August 23 – 29, 2007 9 Nadir Angle Distribution without alignment more information: talk of V. Flaminio on Monday  from above from below *

10. 13th Lomonosov Conference Kay GrafUniversity of Erlangen August 23 – 29, 2007 10 The Acoustic Setup ~240m ~120m ~1m acoustic storey (AS) 6 storeys with 6 sensors each at different length scales (1 m – 350 m) ~15m ~350m acoustic storey (AS) major questions: acoustic noise at the ANTARES site rate of neutrino-like background pressure pulses

11. 13th Lomonosov Conference Kay GrafUniversity of Erlangen August 23 – 29, 2007 11 ~ 10m hadronic cascade ¼ 1km S. Bevan et al., arXiv:0704.1025 energy deposition in (hadronic) cascade ) bipolar pressure pulse in disc shape The Acoustic Signal of UHE Neutrinos

12. 13th Lomonosov Conference Kay GrafUniversity of Erlangen August 23 – 29, 2007 12 background noise at low wind speed: ¼ 3 mPa (rms, 1 – 100 kHz), P (1EeV@1000m) Noise in the Deep Sea N.G. Lehtinen et al., Astropart. Phys., 17(2002), p. 279

13. 13th Lomonosov Conference Kay GrafUniversity of Erlangen August 23 – 29, 2007 13 DAQ Characteristics preliminary inherent noise comparable to lowest sea state typical sensitivity: ¼ 0.2 V/Pa variable post amplification: gain factor ¼ 1 – 500 digitization: in the sea at 16bit with 125 – 500 kSamples/sec 1knot 3knots 10knots inherent noise

14. 13th Lomonosov Conference Kay GrafUniversity of Erlangen August 23 – 29, 2007 14 Simulations of an Acoustic Detector T. Karg, PhD Thesis, astro-ph/0608312 (2006) strongly dependent on detection threshold of sensors ) design and test efficient signal processing algorithms without quality cuts

15. 13th Lomonosov Conference Kay GrafUniversity of Erlangen August 23 – 29, 2007 15 Simulations of an Acoustic Detector T. Karg, PhD Thesis, astro-ph/0608312 (2006) GZK event rate: 0.01 – 0.1 per km 3 yr ) detector size > 100 km 3 (not with optical detector) without quality cuts

16. 13th Lomonosov Conference Kay GrafUniversity of Erlangen August 23 – 29, 2007 16 Summary and Outlook Astroparticle physics with neutrinos is important and complementary to the study of other cosmic particles The ANTARES neutrino telescope is approaching its completion 5 lines are working well and delivering a lot of physics data ) first neutrino candidates Analysis of the data is in progress, understanding of the detector has to be improved Feasibility test for a future acoustic detector will start this year with an dedicated array of sensors