Sebastian Bösersboeser@ifh.de

Acoustic test setup at south pole

IceCube Collaboration Meeting,

Berkeley, March 2005

Acoustic test setup at pole – 2 sboeser@ifh.de

Motivation

Absorption length ≈ few km temperature dependant

depth dependant

Speed of sound / refraction vice ≫ vwater

larger signals ( Pmax ∞ vice2 )

density dependant refraction of surface noise

Noise level determines energy threshold

Background events few signal events/year

few transient events or good suppression

Evalution of acoustic detection needs acoustic parameters of south polar ice

Acoustic test setup at pole – 3 sboeser@ifh.de

Setup

Use IceCube 3 distant holes down to 400 m

7 levels per hole sensors transmitters auxiliary

Surface digitization String PCs

DAQ Power Fiber LAN

Acoustic test setup at pole – 4 sboeser@ifh.de

Acoustic stageIn all three holes

at the same height do measurement in same layer

sensor and transmitter at each stage reduce systematic error in redundant setup

Sensor module and transmitter module close together check with low signals standard pressure housing

10 cm diameter steel tube end caps with commercial penetrators

String support own steel cable avoid signal shielding by IceCube cable

need spacer

Auxiliary devices temperature or pressure senors commercial hydrophones

Acoustic test setup at pole – 5 sboeser@ifh.de

Acoustic stage: sensor

Sensor module based on existing design PZT5 piezoceramics plus

amplifier directly coupled to steel tube

three channels per module local coincidences directional information

Power supply cable losses

use larger supply voltage

±5V generated in module

Acoustic test setup at pole – 6 sboeser@ifh.de

Acoustic stage: transmitter

Active element piezoceramic transducer

signals ≥ 1000 V possible no orientation possible

ring-shaped ceramic azimuthal symmetry

broad resonance large pressure amplitude

directly coupled to the ice calculable system

HV Signals Problem: cable capacitance

down in the ice use LC-circuits

sine bursts and pulses

Acoustic test setup at pole – 7 sboeser@ifh.de

Cables

Option 1: flexible outdoor robot cable 6×2, 8×2 … 16×2 twisted pairs 0.51 mm2 (ATW24), 100 Ohm

loss: < 2 dB/100m used for moving parts at -40 deg

≈ 6 € / m (8×2 one cable)

Sensors differential signals

3×2 (twisted pairs) power supply

1×2

Option 2: use cheap ethernet cables 4×2 twisted pairs 0.52 mm2 (ATW24), 100 Ohm

loss: < 2 dB/100m two free pairs from transmitter

use for auxiliary sensors tested for -20 deg

test at lower temperatures

≈ 0.3 € / m (4×2 two cables)

Transmitters signal

1×2 power supply

1×2

Acoustic test setup at pole – 8 sboeser@ifh.de

String PC

Limitations cable costs cable losses

DAQ at top of each string

String PC DAQ board(s) Power supply Fiber LAN switch only used for data handling

slow CPU, small disk buried in snow

waterproof container

Acoustic test setup at pole – 9 sboeser@ifh.de

String PC: DAQ

DAQ requirements Low sampling rates low data rates

use of the shelf DAQ

Proposal: NI-DAQ 6259 16 differential inputs

two cards per strings 1.25 MHz single channel 1.0 MHz multichannel

83.3 kHz per channel digital and analog triggering variable gain: ± 50 mV to ± 10 V

large dynamic range 4 differential outputs

transmitter signals

Acoustic test setup at pole – 10 sboeser@ifh.de

String PC: Power supply

Power consumption Wire resistance: AWG24 (0.5mm2), 500m

86 ohm / pair

Sensor ± 5V / 30mA per amplifier

~ 1W / 100mA per module cable loss (86ohm, 0.1A) ΔU = 8.6V

Transmitter +5V / 200mA,

~ 1W per module cable loss (86ohm, 0.2A) ΔU = 17.2V

Power Supply: TXL Series Uin = 86V-264 VAC 50/60Hz size 99x82x35 mm

fits into standard PC housing sensors: TXL 035-1515D

Uout = ±15V / 1.3A transmitters: TXL Series, TXL 060-24S

Uout = 24V / 2.5A

Total: ~15 W per string

Acoustic test setup at pole – 11 sboeser@ifh.de

Cost estimate

Item Quantity Cost Total

Sensor modules 21 200,- € 4.200 €

Transmitter modules 21 300,- € 6.300 €

Auxiliary sensors (temperature, pressure,…) 21 10,- € / ? 210 €

Sensor cables 4.440 m ≈ 3,- €/m ≤ 15.000 €

Transmitter cables 4.440 m ≈ 3,- €/m ≤ 15.000 €

Master PC 1 2.000,- € 2.000 €

String PC 3 1.000,- € 3.000 €

DAQ card 6 1.195,- € 7.170 €

Power supply 6 50,- € 300 €

Fiber LAN switch (String PC) 3 500,- € 500 €

Fiber LAN switch (Master PC) 1 1.000,- € 1.000 €

Waterproof PC container 3 500,- € 1.500 €

PC Power cable ≤ 1000 m 2,- €/m 2.000 €

Fibre LAN cable ≤ 1000 m 2,7 €/m 2.700 €

Total sum 60.880 €

Acoustic test setup at pole – 12 sboeser@ifh.de

Project schedule 2005

April May June July August September October

WK 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44

Sensor finalization

Sensor and transmitter building

Sensor and transmitter calibration Setup

whole systemBuild DAQ system

Test system in lake

DAQ software developement

Software testing

Order parts

Parts arrive

Ship to pole

Acoustic test setup at pole – 13 sboeser@ifh.de

Constraints from IceCube

Cargo cables, PCs, DAQ Sensor and transmitter modules

total cargo need ≤ 5m3

Manpower deployment: trained person

at the spot commissioning: DAQ connection

and setup, primary testing one person, two weeks

Deployment separate deployment deployment with string possible

only affecting the last 400 m OMs are in safe depth

find best solution with IceCube deployment responsibles

Interference with IceCube Acoustic signals

1 km above IceCube < 10 mPa signal at OMs

Electric signals low voltage (±5Vpp)

High voltage generated localy low duty cycle (≤ 1%).

DAQ, power supply seperate from IceCube

no interference expected

Acoustic test setup at pole – 14 sboeser@ifh.de

Summary

all components are available and tested

reasonable cost and time scale

! major activities at all other neutrino telescopes

go for pole season 05/06