IceCube radio extension Status and results
Hagar Landsman, Mike Richman, and Kara HoffmanOn behalf of the IceCube Collaboration
Ice index of refraction n(z)
Ice Attenuation Length (point to point)
Environmental noise
Reconstruction algorithms
(2
IceCube’s radio extension
In ice digitization . Combination of ANITA/IceCube/RICE technologies:2 clusters in 2006-20073 clusters in 2008-2009 Depth of 1450 m or 300 mAKA “AURA”
Envelope detection. 6 units deployed at -35, -5 meters (2009-2010)6 units in other depth/location (On top of a building, terminated, -250m)AKA “SATRA”
Calibration
Set of transmitters and passive antennas for calibration (including cable symmetrical antennas)
IceCube-radio hardware
Fully digitized WFs Use IceCube’s resources: holes, comm. and power
Each Cluster contains:Digital Radio Module (DRM) – Electronics 4 Antennas – With front end electronics1 Array Calibration Unit (ACU) - Transmitter
Deployed above the IceCube array:“Free” Deep holes “Free” Power distribution and communication
Signal conditioning and amplification happen at the front end RICE Broad band fat dipole antennas centered at 400 MHz 450 MHz Notch filter 200 MHz High pass filter (2 units with 100Mhz) ~50dB amplifiers (+~20 dB in DRM)
Signal is digitized and triggers formed in DRM (a’la’ANITA) 512 samples per 256 ns (2 GSPS). Wide frequency range and multiple antennas are required for triggering
surface junction
box
Counting house
4
Waveforms and Event Reconstruction
Source at surface: Source In Ice:
Deep KU pulser to DorisSurface pulser to Danielle256 ns 256 ns
(5
Transient detection
Transient detector (“SATRA”)
* 6 in ice units on 3 strings
in holes #8, #9 and #16
* 1 antenna each: 2 antennas per hole.
* 35m and 5 m deep
* Each pair of antennas has a local-coincidence triggering
* Dry holes
* Log amp envelope detection
DAQ box sjb
30 m
5 m
satraIceCube cable
Nick name: SATRA - (Sensor Array for Transient Radio Astrophysics)
Wind generated noise
*The South Pole is electrically insulated, causing a buildup of electrostatic charge, leading to EMI from discharge.
*Elevated noise corresponds to wind speed great than ~20 knots.
*New model: Gordon, Taylor (2008) : E>25 KV/m near surface
(7
*The mystery noise
The mystery noise
(8
*NOAA Sonde (National Oceanic and Atmospheric Administration)
*Model RS80-15*405-406 MHz signal*Fridays only*Plastic baloon (rises
slower)
*MET Sonde *Model RS92-SGP*402-403MHz*Daily *rubber balloons
The noise source
Ray tracing from pulser to SATRA
Sourceat -250m
Bottom antenna-35m
Top antenna -5m D
ep
th [
m]
XY separation [m]
surface
Direct rays
Reflected rays
Measured time differences:Time differences between direct raysAnd between direct and reflected rays can be calculated
10
SATRA Average envelope WFs For In Ice Pulser events
Hole 16, Bottom Hole 16, Top
Hole 9, Top
Hole 8, Top
Hole 9, Bottom
Hole 8, Bottom
~44 bins = ~139 ns
Simulated results=137 nsSimulated results=14 ns
(11
n_c
n_s
hallo
w
Simulated absolute travel time from pulserto top antenna, hole 8
no solution
2950 ns
2650 ns
• Improved Ray trace simulation (Chris Weaver)• n(z) = n_d + (n_s - n_d)*en_c*z
•Values for n_d and n_s from RICE data down to 150m and ice cores down to 240m.
Simulated time diff between Direct & secondary ray For Bottom ant hole 16
n_c
n_s
hallo
w
180 ns
140 ns
90 ns
30 ns
50 ns
n_c
n_s
hallo
wSimulated Time differences between direct hits in hole 9
bottom and top
This is why this channel did not see the pulser.It is in the invisible region due to ray tracing
Based on set of hit time differences between antennas and between primary and secondary hits on the same antenna, a limit on the index of
refraction modeln(z) = n_d + (n_s - n_d)*en_c*z
can be obtained.Systematics taken into account: n_deep, Geometry, timing resolution, WF
features
Index of Refraction
Attenuation length
Attenuation length
Final best fit attenuation length profile for different pairs of antennas. Systematics currently being evaluted.
Prelim
inary
• IceCube provided unique infrastructure and opportunity to study the RF properties of South Polar ice, develop RF hardw are for an Askaryan array, and study the su itability of the RF noise environm ent for an englacia l array.
•Favorable ice properties and noise environm ent have been found.
• An array concept has been proposed, and a new collaboration, independent of IceCube has been form ed. The first phase is funded (see ta lks by Am y Connolly and Kara Hoffm an).
• IceCube provided unique infrastructure and opportunity to study the RF properties of South Polar ice, develop RF hardware for an Askaryan array, and study the suitability of the RF noise environment for an englacial array.
•Favorable ice properties and noise environment have been found.
• An array concept has been proposed, and a new collaboration, independent of IceCube has been formed. The first phase is funded (see talks by Amy Connolly and Kara Hoffman).
Summary
Radial distances of Rx’s to Transmitter