Simulating Hadronic Cascades

As the slide show illustrates, the acoustic signal of a neutrino originates from the heating effect of the particle cascade resulting from its collision within a particular medium. This process has been studied in detail by the ACORNE collaboration via Monte Carlo simulations using the GEANT4 and CORSIKA programs.
A parameterisation of the cascades longitudinal and radial energy density, in water and ice, has been determined.

Acoustic Pulse Calculations

Once the cascade energy density is known, the corresponding pressure differential at some other location can be calculated. This has been achieved with the additional feature of stochastic fluctuations in cascade profiles.

A Calibrated Source

It is desirable to have a calibrated acoustic source that can be used to emit neutrino-like pressure pulses for measurement by a suitable detector. A single omni-directional transducer has been characterised and subsequently driven to do this. The next step is to develop a linear array of transducers that produced a phased output which mimics the acoustic pancake produced by a UHE neutrino induced hadronic cascade.

The Rona Field Trip

The ACORNE collaboration utilises the QinetiQ Underwater Acoustic Range at Rona in the Northwest of Scotland. The acoustic calibrator was successfully deployed in the Inner Sound during September 2008.

Analysis of Rona Data

The ACORNE collaboration has in excess of 14TB of FLAC compressed audio data taken by the Rona hydrophones. A preliminary analysis of these data has been presented and is written about in a thesis.

Sensitivity Calculations

The ACORNE collaboration has also investigated the feasibility of kilometre scale arrays of hydrophones as UHE neutrino telescopes.

Summer Student Work

Nuffield funded Summer student Courtney Williams worked on the project during the summer of 2008. Courtney went on to present her work at The Big Bang UK Young Scientists and Engineers Fair where she was awarded the CREST EU Competition for Young Scientists' Prize.

Cascade Profile
2-dimensional profile of a hadronic cascade produced by GEANT4 simulation. For showers above 100 TeV a modified version of the CORSIKA program is used to determine the energy deposition.


Maximum Pulse Height
Variation of the maximum pulse height as a function of distance and angle from a 10¹¹ GeV primary.


Laboratory Based Development
Transducers are first tested in the ACORNE laboratory at The University of Sheffield before being deployed in the field.


Deployment In The Field
A LabView Virtual Instrument was used to drive an omnidirectional transducer with MATLAB generated waveforms above the QinetiQ Acoustic Range at Rona


Diving for Neutrinos
A short duration, impulsive event in the data from Rona. Many sources of 'noise' are present in the Inner Sound hpwever these have been utilised as a sample data set in order to develop the ACORNE data acquisition chain. Subsequent analysis of these signals aims to discriminate between environmental, biological and anthropogenic sources and neutrinos.


Sensitivity of km³ Hydrophone Arrays
The acoustic detection of UHE neutrinos can be competitive with optical and radio based experiments but undoubtedly the best performance will come from hybrid telescopes.

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