ANTARES: Towards Acoustic Detection of Highest Energy Neutrinos

Kay Graf for the ANTARES Collaboration

Erlangen Centre for Astroparticle Physics

VLVT 09, Athens, Oct. 13th – 15th 2009

Outline

• Motivation• The AMADEUS System• Positioning• Source Reconstruction

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 2

Motivation

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 3

Ultra-high Energy Neutrino Astrophysics

at energies above 1014-15eV:

• universe becomes opaque to

photons at Mpc range

• CR protons, nuclei are galactic up to

~1018eV, suffer GZK cut-off above

that

• neutrinos unabsorbed at all energies

→ sources exist to at least

3x1020eV

• UHE neutrinos are the only viable

messenger beyond the local

universe

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 4

vi

able

thr

ough

out

thes

e re

gion

s

P. Gorham

Highest Energy Neutrinos

• astrophysics:

origin of UHECR

GZK neutrinos

• cosmology:

top-down scenarios

topological defects

• particle physics:

neutrino cross section

5Kay Graf (ECAP) – VLVnT 09, Athens – October 2009

log10(E[eV])1614 2418

TD

20 22

T. Karg, arXiv:astro-ph/0608312

10-4

10-8

10-6

10-10

Flu

x ×

E2 [e

V m

-2 s

-1 s

r-1]

water/iceCherenkovtelescopes

complementary techniques

for GZK : >100km2 ∙ 2∙ year detector needed

(U)HE Detection Methods

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 6

neutrino cascadecascade

hydrophone arrayAcoustic Detection

water, ice, salt

att > 1km (water)

sonic wavesonic wave

radio radio CherenkovCherenkov

cascadecascade

antenna arrayRadio Cherenkov

ice, salt, rock

att ~ 1km (ice)

opticalopticalCherenkovCherenkov

PMT arrayOptical Cherenkov

water, ice

att < 100m

• balloon• satellite• telescope

+ hybrid detectors

Acoustic Signal Properties

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 7

Ecasc= 1 EeV @ 1km

bipolar signal (~10kHz) with disk-like geometry

Acorne Coll. astro-ph/0704.1025

peak pressure

(mPa/EeV)

T. Karg, astro-ph/0608312v1

log10 (radial distance (m))di

stan

ce a

long

sho

wer

axi

s (m

) shower maximum

log10 (radial distance (m))

Simulations of an Acoustic Detector

• strong dependence: Veff(Pthres)

• Pthres mainly given by ambient noise

• a threshold of 5mPa seems reachable in the deep-sea

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 8

T. Karg, arXiv:astro-ph/0608312

200 acoustic antennas/km3

Pthres

The AMADEUS System

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 9

The AMADEUS Project

Feasibility Study

• detector environment (hybrid)

• detector calibration functionality

• sensor design and positioning

• background studies

• signal processing techniques

integration of acoustic setup into the ANTARES neutrino telescope

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 10

The ANTARES Neutrino Telescope

• optical Cherenkov Telescope

• 875 PMT• at 2500m water depth• Vinst~ 200 x 200 x 400 m3

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 11

ANTARESsite

F

The AMADEUS System

• taking data since 5-Dec-2007

• completely installed since 30-May-2008

• acoustics on L12: data from 6-Sep to 24-Dec 2008

“pingers“ (acoustic RxTx) on each anchor

12Kay Graf (ECAP) – VLVnT 09, Athens – October 2009

AMADEUS Facts

• characteristics- 36 sensors at 6 storeys

(1 – 350m distance, 34 active)- 16bit @ 250kSps sampling- ~ -125dB re 1V/Pa sensitivity- ~85-90% uptime

• data acquisition- all data to shore- raw: 20 MByte/s (1.5 TByte/d) - filtered: 0.3 MByte/s (4 GByte/d), up to now: 4

TByte - excellent stability of all DAQ parts

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 13

Data Samples: Amplitude Histograms

noise at different sensors• gaussian profile• linear correlation between

sensors (factor ~ 99%)

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 14

noise and transient• additional tails• ~60dB S/N (SINAD), no

significant crosstalk

Sam

ple

s (p

er

AD

C c

ount)

Sam

ple

s (p

er

AD

C c

ount)

Positioning

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 15

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 16

Positioning: Method for Reconstruction

use emissions from the ANTARES acoustic positioning system (not directly connected with AMADEUS)

→ positioning of individual sensors:• use absolute time from > 3 pingers:

| rreception – remission | = cs ¢ (treception – temission – toffset )

• treception by threshold crossing of signal envelope

• temission from positioning system

→ position/orientation by fitting storey geometry

Positioning: Example

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 17

• 5 days of data• completely independent derivation of heading

Acoustic Modules (AMs)

Piezo sensors + preamplifiers

design allows for integration of acoustic sensors into pressure housing of photo sensors

no need for additional mechanical structures

18Kay Graf (ECAP) – VLVnT 09, Athens – October 2009

Pinger Signals for Reconstruction of Hydrophones and AMs

AMs

Hydros

19Kay Graf (ECAP) – VLVnT 09, Athens – October 2009

signal quality of AMs slightly degraded w.r.t. hydrophones(coupling, ringing of sphere, ...)

Positioning with AMs

2

30mmσ

• calculate difference of individually reconstructed sensor position• some issues/systematics need to be investigated

20Kay Graf (ECAP) – VLVnT 09, Athens – October 2009

0

1

23

45

• systematic effects due to orientation of sensors w.r.t. pingers need to be investigated

• for two sensors with distance at 250mm (in a sphere) better than 10° resolution reachable

21Kay Graf (ECAP) – VLVnT 09, Athens – October 2009

Sensors 0 and 2

Heading on AM Storey

Positioning Option for KM3NeT

AMADEUS-like acoustic sensors have the potential to combine:

• positioning

• investigation of acoustic neutrino detection techniques

• marine science

Acoustic Modules (AMs) allow for an integration of acoustic sensors into Opto-Acoustical Modules (OAMs).

First Measurements in the Lab:

• no significant degradation of performance of acoustic sensors by ANTARES HV base

• noise expected mainly from DC-DC converter

22Kay Graf (ECAP) – VLVnT 09, Athens – October 2009

Source Reconstruction

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 23

Source Direction Reconstruction: A Dolphin

• beam forming or time difference algorithms used• uncertainty <1°

(mainly due to binning in the algorithm)

24

Inte

nsity

(au

)

-180 0 180f (°)

0 0.5 1time (ms)

90

0

-90

(°

)

1

0

-1

Am

plit

ude

(a

u)

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009

most probable source direction

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 25

Angular Distribution of Marine Sound Sources• direction reconstruction for one storey• all types of transient signals included• origin points horizontal to north• one month of data

Tracking of a Source

• reconstruction with one storey• all triggered events within 500s displayed

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 26

Summary

• at UHE neutrinos are the only viable messenger beyond the local universe

• need a >100km2 ∙ 2∙ year detector

•acoustic detection promising candidate

• complementary to optical and radio techniques (hybrid detection)

•AMADEUS in ANTARES: feasibility study for a future acoustic detector

• dedicated array in a detector environment – hybrid detection possible

• successfully operated since 12/2007

• return of experience for future arrays (opto-acoustical?)

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009 27

Funded by: