Combined Opto-Acoustical Sensor Modules for KM3NeT

Alexander Enzenhöfer on behalf of the

KM3NeT consortium

ARENA 2012

Erlangen, 19.06. – 22.06.2012

KM3NeT

Alexander Enzenhöfer, ARENA 2012, 19.06. - 22.06.2012 2

• Water Cherenkov neutrino telescope• Multi-cubic-kilometre instrumented volume• Located in the Mediterranean Sea• At least 300 vertical structures (detection units)

with several hundred metres length, housing photosensors

Requirements

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• Relative positions of the photosensors have to be determined with precision better than 20 cm (corresponding to nanosecond precision in timing)

• Dynamic environment needs constant monitoring• Long-term stability of all utilised parts• Resistance to environmental influences (salinity,

pressure)

“Acoustic Positioning System“

• Dedicated acoustic emitters at fixed positions (sea floor)

• Acoustic receivers along each detection unit• Multiple time delay measurements and

subsequent trilateration

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Storey 2

Compass board

“AcouBoards”

Experience from AMADEUS

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Comparison: Compass – acoustical sensors

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Optical and acoustical detection technique

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Acoustical sensor

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Small piezo cylinder (18 x 12 mm) with preamplifier inside aluminum tube(21 mm x 30 mm)

Mainamplifier board (61.5 x 32.0 mm) with Bandpass (2 kHz – 125 kHz)

Low power consumption: < 10 mA @ 3.3 V (Piezo + preamp)

< 40 mA @ 3.3 V (system including mainamplifier)

Basic concept for an Opto-Acoustical Module

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Acoustic Module from AMADEUS (acoustic sensors inside glass sphere)

Opto-Acoustical Module (OAM, acoustic sensors inside glass sphere next to PMT(s))

Single-PMT design

• Cooperation with colleaguesfrom INFN and INFN-LNS(Italy)

• NEMO Phase II infrastructure• 13‘‘ glass sphere• 1 x 10‘‘ PMT• Deployment planned for this

year at Capo Passero (Sicily)

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Results I

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Frequency spectrum for hydrophone (top)and OAM (bottom) for applied sinusoidal ultrasonic signal (30 kHz)

Frequency spectrum for OAMs showing interference with calibration device inside the module

Multi-PMT design

• Cooperation with colleaguesfrom Nikhef (Netherlands)

• KM3NeT infrastructure• 17‘‘ glass sphere• 31 x 3‘‘ PMTs

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Results II

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Frequency spectrum of the OAM noise next to 5 powered PMTs

Time domain signal for knocking on the glass sphere

Summary and outlook

• Flexible design allows for sensor integration to different module layout

• Sensor and readout allows for different applications (positioning, marine science, acoustic particle detection, ...)

• No showstopper observed so far• Detailed investigation of acquired data• Identify and solve further technical difficulties• Some more tests in the final configuration• Tests under real conditions

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The research leading to these results has received funding from the European Community Seventh Framework Programme under grant agreement n. 212525 and from the Sixth Framework Programme under contract n. 011937