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Transcript of radio lobe
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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