radio lobe

sound disk

t

p

optical light cone

The Vision

*) see e.g. A. Ringwald ,ARENA 2005

Build ~100 km3 hybrid detector to:

Confirm GZK cutoff !

Do physics with extremelyhigh energy cosmic neutrinos*)

- astrophysics - E > 1016eV : study origin of cosmic rays - (AGN’s, black holes, GZK cutoff, …)

- particle physics - E > 1018eV :study neutrino cross section (sphalerons, mini BH, strong,…)

- cosmology - E > 1021eV : study relic neutrino background radiation (UHE absorption at CBR )

Acoustic R&D in IceCube 2002 2003 2004 2005 2006 2007

start development of glaciophones

test in lab and at accelerators

calibration of sensors and transmitters

constructionand test of

SPATS Firs

t S

PA

TS

dep

loym

ent

Firs

t S

PA

TS

res

ults

Improvement (S/N)ib = 50 (S/N)gb = 15

In-s

itu

tes

t st

arts

hybr

id d

etec

tor

sim

ulat

ion

The South Pole Acoustic Test Setup

SPATS

3 strings deployed Jan/07+1 string deployed Dec/07

instrumented depth:80m - 500m

per string: 7 sensors, 7 transmitters

string-PC: digitization, time-stamp, monitoring (p, T)

master-PC: process steering, GPS data storage data transfer via satellite

The Four SPATS Goals

Get information about:

1.) Sound speed: what is the sound speed value?is it depth dependent (= refraction?)

2.) Transient events:are there transients events?what are their features (rate, sources)? could they be a significant source of background?

3.) Noise:what is the noise level?which energy threshold does it correspond to?

4.) Attenuation coefficient:never measured up to know, only models are known

is it depth dependent?is it frequency dependent?

Needs time information

Needs amplitudeinformation

Sound Speed Results

bbb

paper submitted to Astroparticle Physics

First observation

of shear waves

in SP ice!

vp(375 m) = 3878 ± 12 m/s

vS(375 m) = 1976 ± 8 m/s

Absolute Noise Level Resultσ

(V)

σ increaseafter deployment

17 Jun 0824 Dec 07

IceCube drilling

SPATS:

320 m

400 m

500 m

σ(V

)

σ increaseafter deployment

17 Jun 0824 Dec 07

IceCube drilling

SPATS:

320 m

400 m

500 m

σ(V

)

σ increaseafter deployment

17 Jun 0824 Dec 07

IceCube drilling

SPATS:

320 m

400 m

500 m

DS7-2

500 m

GaussianDS7-2

500 m

DS7-2

500 m

DS7-2

500 m

Gaussian- Gaussian- Stable- ≤15 mPa

RW07/08

RW06/07

AM-RW

RW05/06

- more than one year continous data taking

- no surface noise detected

- hear 4 steady sources and at least 8 drill holes during re-freezing

- x-y resolution depends on depth and location with respect to detector typically better than 10 m

- no noise from unknown sources with present trigger conditions

Transient Noise Events

Energy from the time domain

• Use pinger data

• 47 independent measurements

(from 49 combinations available)

• Weighted mean value and error:

α = 3.21+/- 0.56 10-3 m

λ ~ 312+/- 64 m

• No significant depth dependence

• No significant frequency

dependence up to 30 kHz

1 example channel

xxx

SPATS Status Summary

Mission accomplished to ~95% :

- 1) Speed of Sound + Refractionspeed of sound constant below 200 mno refraction

- 2) Sound Attenuation Length

λ = 300+/- 100 m, factor 30 smaller than expected

still to measure: frequency and depth dependence possible explanation: larger influence of scattering

- 3) Absolute Noise Level

gaussian and stable≤ 10 mPa ( with reasonable assumptions)

- 4) Transient Signal Rate

small and until now all from identified sources

easy to separate from neutrino signal

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