1. Sebastian Böser sboeser@ifh.de Acoustic test setup at south pole IceCube Collaboration Meeting, Berkeley, March 2005

2. Acoustic test setup at pole – 2 sboeser@ifh.de Motivation Absorption length ≈ few km temperature dependant  depth dependant Speed of sound / refraction v ice ≫ v water  larger signals ( P max ∞ v ice 2 ) 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

3. 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

4. Acoustic test setup at pole – 4 sboeser@ifh.de Acoustic stage In 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 sensors commercial hydrophones

5. 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

6. 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

7. 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 mm 2 (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 mm 2 (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

8. 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

9. 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

10. Acoustic test setup at pole – 10 sboeser@ifh.de String PC: Power supply Power consumption Wire resistance: AWG24 (0.5mm 2 ), 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 U in = 86V-264 VAC 50/60Hz size 99x82x35 mm  fits into standard PC housing sensors: TXL 035-1515D  U out = ±15V / 1.3A transmitters: TXL Series, TXL 060-24S  U out = 24V / 2.5A Total: ~15 W per string

11. Acoustic test setup at pole – 11 sboeser@ifh.de String PC: Fiber LAN Data rates 2 DAQs x 1.0 MS/s x 16 Bit  ≤ 32 MBit/s per string Optical fiber LAN 2- or 4-port (String-PC/Master-PC) 1 GBit/s standard 10 km Point-to-Point on single mode fibers Cheap outdoor cable rated -50 degrees  test for large arrays

12. Acoustic test setup at pole – 12 sboeser@ifh.de Cost estimate ItemQuantityCostTotal Sensor modules21200,- €4.200 € Transmitter modules21300,- €6.300 € Auxiliary sensors (temperature, pressure,…)2110,- € / ?210 € Sensor cables4.440 m≈ 3,- €/m≤ 15.000 € Transmitter cables4.440 m≈ 3,- €/m≤ 15.000 € Master PC12.000,- €2.000 € String PC31.000,- €3.000 € DAQ card61.195,- €7.170 € Power supply650,- €300 € Fiber LAN switch (String PC)3500,- €500 € Fiber LAN switch (Master PC)11.000,- €1.000 € Waterproof PC container3500,- €1.500 € PC Power cable≤ 1000 m2,- €/m2.000 € Fibre LAN cable≤ 1000 m2,7 €/m2.700 € Total sum60.880 €

13. Acoustic test setup at pole – 13 sboeser@ifh.de Project schedule 2005 AprilMayJuneJulyAugustSeptemberOctober WKWK 1617181920212223242526272829303132333435363738394041424344 Sensor finalization Sensor and transmitter building Sensor and transmitter calibration Setup whole system Build DAQ system Test system in lake DAQ software development Software testing Order parts Parts arrive Ship to pole

14. Acoustic test setup at pole – 14 sboeser@ifh.de Constraints from IceCube Cargo cables, PCs, DAQ Sensor and transmitter modules  total cargo need ≤ 5m 3 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 locally  low duty cycle (≤ 1%). DAQ, power supply  separate from IceCube  no interference expected

15. Acoustic test setup at pole – 15 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