Title: Listening for Neutrinos The ACORNE Project
1Listening for NeutrinosThe ACORNE Project
- Lee Thompson
- University of Sheffield
- Imperial College
- 11th June 2008
2Why look for neutrinos?
- Much of our understanding of the Universe comes
from the EM spectrum
3Why 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
4High energy ? ray sources 99
5High energy ? ray sources 07
6High 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
7HESS 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
8Sources AGN/Blazars
9AUGER 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
10Top-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
11HE Neutrino Detection Methods
Optical Cerenkov Works well in water,
ice Attenuation lengths of order 50m to 100m
(blue light) Most advanced technique
12A simulated ANTARES event showing the muon
trajectory, Cerenkov light rays and PMT hits
13ANTARES Detector Design
3 PMTs per storey 25 storeys per string
Buoyancy Module
EO cable to shore
14.5m
450m
Junction Box
60m
Anchoring Weight
14 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
15AMANDA Sky Map
16HE 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
17Radio 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
18Radio Detection from above
19HE 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
20Acoustic Detection Principle
21Acoustic 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
22Technique Comparison
23Acoustic 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
24Test 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
25ACoRNE 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)
26Play the Rona Fly-by Movie!
27Acoustic Calibration Development
Progression lab tank pool lake open sea
Tx - omnidirectional 1.8dB _at_ 10kHz
Rx - flat frequency response
28Acoustic 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
29Rona 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
30Rona field trip data and spectra
31Data 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
32Neural Network
- Correlation matrices red strong correlation,
blue strong anti-correlation, green no
correlation
33Simulation 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
34Sensitivity 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
35Other Acoustic Sites SAUND
36SAUND results
195 days livetime
SAUND-II (56 hydros) taking data since June 2006
37Other 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
38Future 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
39Future 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
40Sensor 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
-180
Points MeasurementLine Prediction
sensitivity dB re 1V/µPa
-190
data sheet -192dB.25mV/Pa
-200
10 20 30 40 50 60 70 80 90kHz
41Sensor Development
- Development of novel hydrophone designs
- From Pisa an air-backed mandrel hydrophone
- Incorporates a Bragg grating
- Prototypes developed
- Improvements in frequency response needed
42Sensitivity 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
43Sensitivity 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
44Observation of bio-activity
- Important result sperm whale transits more
frequent than previously believed
45Dolphin clicks at Rona
46Summary
- 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)