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

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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

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Waveforms and Event Reconstruction

Source at surface: Source In Ice:

Deep KU pulser to DorisSurface pulser to Danielle256 ns 256 ns

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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

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*The mystery noise

The mystery noise

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*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

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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

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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