Listening for Neutrinos The ACORNE Project

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Listening for NeutrinosThe ACORNE Project

• Lee Thompson
• University of Sheffield
• Imperial College
• 11th June 2008

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Why look for neutrinos?

• Much of our understanding of the Universe comes
  from the EM spectrum

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Why look for neutrinos?

• Neutrinos open up a new window on the Universe
• Photons are absorbed in interactions with the
  interstellar medium (PeV ?-ray - microwave bkgd,
  TeV ? -ray - IR/optical bkgd)
• Charged particles may be deviated in
  (extra-)galactic magnetic fields - loss of
  information on astrophysical source
• Neutrinos form a powerful probe of the Universe
  even at large redshifts

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High energy ? ray sources 99
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High energy ? ray sources 07
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High energy ? ray sources 07

• 71 sources
• 7 SNR
• 18 PWN
• 21 Un.Gal.
• 2 Diffuse
• 4 Binary
• 19 AGN
• 3 in Gal. plane have no counterparts

• Each of these sources is a high energy cosmic
  accelerator of primary electrons or nuclei

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HESS Unidentified Sources

• Dark accelerators?
• Significant fluxes of VHE ?-rays without
  accompanying x-ray and radio emission suggest
  absence of relativistic electrons and the
  presence of energetic nucleons
• Aharonian et al.
• astro-ph/0510397

• Completely hidden (neutrino only) sources?
• Young SN shell
• Thorne-Zytkow stars
• Cocooned massive black hole
• AGN with standing shock
• pre AGN
• Berezinsky, Dokuchaev
• astro-ph/0002274

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Sources AGN/Blazars
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AUGER and AGN

• Recent AUGER Science paper correlates 20 out of
  27 UHE events with known AGN

• Cen A has 2 events within 3.10, no events from
  Virgo region

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Top-down models

• GZK cut-off question in recent years has lead to
  a number of top-down models being developed
• Strongly interacting neutrinos
• New neutral primaries
• Violation of Lorenz invariance
• Decaying supermassive dark matter
• Instantons, excitons
• etc
• Many of these models predict, e.g. enhanced
  neutrino cross-sections at ultra high energies

Neutrino-nucleon cross-sections for low- scale
models of quantum gravity involving e.g. extra
dimensions
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HE Neutrino Detection Methods
Optical Cerenkov Works well in water,
ice Attenuation lengths of order 50m to 100m
(blue light) Most advanced technique
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A simulated ANTARES event showing the muon
trajectory, Cerenkov light rays and PMT hits
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ANTARES Detector Design
3 PMTs per storey 25 storeys per string
Buoyancy Module
EO cable to shore
14.5m
450m
Junction Box
60m
Anchoring Weight
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ICECUBE
Design Specifications

• Fully digital detector concept.
• Number of strings 75
• Number of surface tanks 160
• Number of DOMs 4820
• Instrumented volume 1 km3
• Muon effective area see plot
• Angular resolution of in-ice array lt 1.0

Current Status

• 9 strings, 16 surface stations
• 604 deployed DOMs, 594 taking data (98)
• Instrumented volume 0.1 km3
• Collecting physics data

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AMANDA Sky Map
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HE Neutrino Detection Methods
neutrino
Optical Cerenkov Works well in water,
ice Attenuation lengths of order 50m to 100m
(blue light) Most advanced technique
Radio Cerenkov Long (order km) attenuation
lengths in ice and salt First generation
experiments proposed
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Radio Askaryan Effect

• Proposed in 1961
• In a neutrino-induced cascade there is a net
  moving negative charge 20 of overall charge
• Predominantly due to positron annihilation and
  AZ ? Az1 e-
• This relativistically moving charge will produced
  Cerenkov radiation

• This time in the radio spectrum - typically 0.1
  to few GHz
• Should be coherent (PRF ? E2 at radio frequencies
• Should be above thermal noise at high E
• Detectable at a distance
• Radiation polarised

• Target requirements
• radio quiet
• instrumentable
• radio transparent

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Radio Detection from above
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HE Neutrino Detection Methods
neutrino
Optical Cerenkov Works well in water,
ice Attenuation lengths of order 50m to 100m
(blue light) Most advanced technique
Acoustic Detection Very long attenuation lengths
in water (order 10km), ice and salt Huge
effective volumes may be possible
Radio Cerenkov Long (order km) attenuation
lengths in ice and salt First generation
experiments proposed
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Acoustic Detection Principle
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Acoustic Detection Features

• Typical cylindrical volume over which the
  hadronic energy is deposited is 20m long by a
  few centimetres wide (95 of energy at 1020eV)
• The energy deposition is instantaneous with
  respect to the signal propagation
• Hence the acoustic signal propagates in a narrow
  "pancake" perpendicular to the shower direction
  in analogy with light diffraction through a slit

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Technique Comparison
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Acoustic Pulse Attenuation

• The acoustic signal detected at the hydrophone is
  modified by 3 factors
• geometric (1/r) attenuation,
• angular spread using parametrisations of the
  modelled spread (using Fraunhofer diffraction
  theory) fit to 2 Gaussians (hydrophones more than
  5 degrees out of the pancake plane are not
  considered)
• attenuation due to the medium - again from
  studying the acoustic signal as a function of the
  distance from the source and the water
  properties. Performed on matched filter output

Angular spread Medium losses
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Test Beam Experiments

• Results from test beam experiments in late 1970s
  confirming bi-polar acoustic pulse in a test beam

SULAK ET AL NIM 161 (1979) 203

• Signal amplitude vs. energy deposition along with
  our prediction from first principle studies
• Pressure proportional to Energy - coherence

• Signal amplitude vs. water temperature - warmer
  is better!
• P proportional to ?(T) - thermo-acoustic origin

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ACoRNE and RONA

• Rona hydrophone array, a submarine ranging array
  in North-West Scotland used by the ACORNE
  collaboration

• 7 hydrophones read out continuously at
  16bits,140kHz - a total of (26 Tb uncompressed)
  data taken to date (since December 2005)

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Play the Rona Fly-by Movie!
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Acoustic Calibration Development
Progression lab tank pool lake open sea
Tx - omnidirectional 1.8dB _at_ 10kHz
Rx - flat frequency response
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Acoustic Calibration

• Aim to apply an electrical impulse to a
  hydrophone that will result in a bipolar pulse
  being created in a body of water
• First evaluate the hydrophone response using
  signal processing techniques
• Predicted (5th order LRC model) and measured
  response for single cycle sine wave

• Excitation and response pulses required to
  generate bipolar pulse using this method
• Method used at Rona in summer 2007

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Rona Field Trip August

• In August 2007 we injected a number of different
  pulse types and amplitudes directly above the
  Rona hydrophone array
• Analysis of these data is underway

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Rona field trip data and spectra
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Data analysis

• Potential discriminators in time/frequency
• Pulse Width
• Pulse Periodicity
• Relative Energy
• Pulse Multiplicity
• Dominant Frequency
• Sinusoidalness
• Bipolarity
• Standard Deviation
• Skewness
• Kurtosis
• all fed into a neural network

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Neural Network

• Correlation matrices red strong correlation,
  blue strong anti-correlation, green no
  correlation

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Simulation Work
105 GeV protons
AstropartPhys V28 3 2007 p366-379

• CORSIKA has been modified to make it work in
  water
• Comparisons with GEANT
• 10 lower at peak
• Showers broader
• NKG parametrisation gives less energy at smaller
  radii - may be important for acoustic/radio
• A neutrino pulse simulator based on CORSIKA
  param. is available

Acoustic pulses for 1011GeV showers
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Sensitivity Calculations

• Studies on the effects of refraction
• Linear SVP distorts the acoustic pancake into a
  hyperbola

• Sensitivity of a large acoustic array to the
  hadronic component of neutrino induced cascades
• 1100 acoustic sensors per km3
• 1-10 years of operation
• 35-5mPa sensor threshold applied
• Maybe some sensitivity to GZK
• NB no refraction in here

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Other Acoustic Sites SAUND
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SAUND results
195 days livetime
SAUND-II (56 hydros) taking data since June 2006
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Other Acoustic Sites NEMO

• ONDE - the Ocean Noise Detection Experiment was
  deployed in January 2005 at the NEMO Test Site in
  Sicily
• 4 hydrophones read out (5 per hour) for 2 years
• Full analysis of noise (by hour, month, etc.)
• Bio coincidences seen

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Future Projects

• Deployment of acoustic sensors in the ANTARES
  optical Cerenkov neutrino telescope
• 2 different acoustic storeys under consideration

• Instrumentation Line with 3 acoustic storeys to
  be deployed in 2007
• Look for co-incidences at different distance
  scales (1m, 10m,100m)
• Of course these studies will be extended to KM3NeT

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Future Projects

• ICECUBE is one place where the infrastructure of
  an optical array is being extended to incorporate
  radio and acoustic sensors
• SPATS the South Polar Acoustic Test Setup is
  designed to test acoustic sensors in ice parallel
  with IceCube deployment
• Tests at a frozen Lake in Sweden in 2006

• January 2007 successful deployment of 63
  receivers, 21 transmitters in 3 IceCube holes

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Sensor Development

• Can we design and build bespoke acoustic sensors
  with performance well-matched to expected signal?
• Requires a good theoretical model of piezo and
  the coupling
• Predictions using equivalent circuits

• Further detailed understanding of piezos is under
  study
• At the microscopic level piezos can be modelled
  using PDEs for an anisotropic material
• Solve using Finite Element Analysis
• Use Laser Interferometry to compare results

example piezo coupled to tank wall
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Points MeasurementLine Prediction
sensitivity dB re 1V/µPa
-190
data sheet -192dB.25mV/Pa
-200
10 20 30 40 50 60 70 80 90kHz
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Sensor Development

• Development of novel hydrophone designs
• From Pisa an air-backed mandrel hydrophone
• Incorporates a Bragg grating
• Prototypes developed
• Improvements in frequency response needed

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Sensitivity Calculations

• Effective volume for a 1 km3 array instrumented
  with different numbers of ANTARES-style acoustic
  storeys
• No improvement in effective volume above
  200AC/km3
• Detection threshold 5mPa

• Detailed acoustic simulation in the Med.
• Sensitivity of a single hydrophone to the EM part
  of the cascade
• Includes effects of complex attenuation
• See astro-ph/0512604

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Sensitivity Calculations

• Hybrid arrays optical, radio and acoustic
  technologies
• 5x2 radio and 300 acoustic sensors per string
  IceCube
• Yields 20 events per year
• Cross-calibration possible

• Effective volume for hybrid arrays involving
  extending beyond IceCube with strings of radio
  and acoustic sensors
• See astro-ph/0512604

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Observation of bio-activity

• Important result sperm whale transits more
  frequent than previously believed

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Dolphin clicks at Rona
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Summary

• Multi-messenger observations of astrophysical
  objects clearly provide valuable information,
  this is also true at ultra high energies
• Acoustic detection of UHE neutrinos is a
  promising technique that would complement high
  energy neutrino detection using the optical and
  radio techniques
• It is likely that any development of a large
  volume acoustic sensor array would piggy back
  the infrastructure of first and second generation
  optical Cerenkov neutrino telescopes
• This is already starting to happen (ANTARES,
  IceCube)