hagar landsman, university of wisconsin, madison

Englacial arrays for detection of cosmogenic neutrinos at the South Pole

IceCube radio extension & ARA

Status and results

APS 2011, Anaheim CA

Hagar Landsman, University of Wisconsin, Madison

The plan for the next 10 minutes(and the next 5 years)

IceCube RF extension Review of current hardwareStatusStay tuned for the next 2 talks

ARA – Askaryan Radio Array New collaborative effortThe grand schemeResults from last season

Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 2

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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)


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IceCube-radio hardwareFully digitized WFs

surface junction

box

Counting house

Use IceCube’s resources: holes, comm. and power

Each Cluster contains: Digital Radio Module (DRM) – Electronics 4 Antennas – With front end electronics 1 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 front end)

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


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Transient style detection

DAQ box sjb

30 m

5 m

satraIceCube cable

Nick name: SATRA - (Sensor Array for Transient Radio Astrophysics)

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


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Some results

• Ice index of refraction n(z) • Ice Attenuation Length (point to point)• Environmental noise• Reconstruction algorithms• See Mike Richman’s and Chris Weaver’s

talk


http://wiki.icecube.wisc.edu/images/0/0d/Sally_16.sample_atwd_A.gif

The ARA Vision•80 km2 area •37 stations equally spaced on a triangular grid•Large separation between stations (1.3km) •3 stations forms a “super cluster”

Sharing power, comms, and calibration source

~30m

Station:•4 closely spaced strings•200m deep •Digitization and Triggering on surface

DAQ Housing

Vpol Antenna

Hpol Antenna

String:•4 antennas, V-pol and H-pol•Designed to fit in 15cm holes•150-800 MHz sensitivity•Cable pass through antenna


Optimized for neutrino counting:A single station can provide and form a triggerDecreases trig time window, lower background and therefore thresholds. Lowers the energy threshold. allowing single string hits.

Detecting down-going events: (4.4sr) Between +45 above, -5 below horizon

Deep ice contributes in higher energies

Hagar Landsman ARA Spring 2011, Madison

~30m200m

2.5 km

1300m

ARA Concept

γ

Interaction

vertexRF radiation

The goal is to count events, not reconstruct the anglesas would be needed for observatory class instrument

ARA - A New collaboration was bornNSF Grant “Collaborative Research: MRI-R2 Instrument Development of the Askaryan Radio Array, a Large-scale Radio Cherenkov Detector at the South Pole“ phase 1 funded

More than 10 institutions from US, Europe, Taiwan, Japan Including IceCube & ANITA & RICE leading institutes.

Hagar Landsman ARA Spring 2011, Madison 9

2010-2011 Install testbed

EMI survey away from the station Test ice properties Testing station prototypes (antennas and electronics)

Calibration activities Install 3 deep RF Pulsers

Conduct Drilling tests Install 3 Wind turbines for testing

This season’s on ice achievementsARA Test Bed

•Successfully installed ~3.2 km away from the Pole.•16 antennas at different depths, down to ~20m.•Signal digitization and triggering happens on a central box on the surface.•Power and comms through cables.

Current status:•Detector is up and running. •Very high efficiency and live time.•No unexpected EMI source.•Up to now, no evidence for wind generated EMI


This season’s on ice achievementsARA Test Bed – Trigger rates

9:00 am weather balloon launch

9:00 pm weather balloon launch

• Test Bed is taking data continuously• Trigger rates are low and stable – below 4 Hz• Clear winter/summer rate difference• Weather balloon launches CW clearly seen

Austral wintersssshhhhh

Austral summerA lot of on-ice

activity


This season’s on ice achievementsARA Test Bed – Galactic center

Noise measured on the surface antennas

preliminary

•Data used from January 18 to April 14• Using two surface antennas• Galactic noise clearly seen over thermal (~ -130 dbW)

Expected galactic

Thermal

TotalCh 1

Ch 2


•3 high voltage calibration Tx installed on IceCube strings at ~1.5 and 2.5km •Deep (2450m) pulser seen by all antennas in the ARA testbed!• Testbed is a horizontal distance of ~1.6 km away- total distance 3.2 km.• Points to an attenuation length of >700m (analysis ongoing).• Time delays between different antennas used to estimate T resolution.

This season’s on ice achievementsDeep pulsers on IceCube strings

σ time=97 ps

mV

ns


Challenges in constructing and operating a large array

Tested two different drills:- Drilling speed- Depth- Hole diameter, smoothness- Logistics

Installed several models of wind turbines

- Measuring and comparing wind speed, power yield.-Weather effects to be evaluated next summer

This season’s on ice achievements


• On going analyses with IceCube radio extensions,

•A collaboration has been formed to build an englacial array large enough to detect cosmogenic neutrinos

• An array concept has been proposed. The first phase funded.

• Fine tuning of instrumentation and detector spacing to be optimized during the development phase

• Successful first South-Pole season

• Facing several challenges in building and operating a large scale detector such as power distributions and fast drilling.

• Work has commenced in preparation for the next season

• Eventual large scale array will determine cosmogenic neutrino flux and tackle associated long standing questions of cosmic rays.

• On going analyses with IceCube radio extensions,

•A collaboration has been formed to build an englacial array large enough to detect cosmogenic neutrinos• An array concept has been proposed. The first phase funded.• Fine tuning of instrumentation and detector spacing to be optimized during the development phase• Successful first South-Pole season • Facing several challenges in building and operating a large scale detector such as power distributions and fast drilling.• Work has commenced in preparation for the next season• Eventual large scale array will determine cosmogenic neutrino flux and tackle associated long standing questions of cosmic rays.

Summary


Backup slides

Hagar Landsman ARA Spring 2011, Madison 16

This season’s on ice achievementsDeep pulsers on IceCube strings

•Blind spots due to ray tracing. The deeper we get the larger the horizon is.

•This was the last access to deep holes.

•3 high voltage calibration Tx installed on IceCube strings at ~1.5 and 2.5km

•Azimuthally symmetric bicone antenna -eliminates systematics from cable shadowing effects

•Goals: radio glaciology and calibration

Hagar Landsman ARA Spring 2011, Madison

Dep

th [k

m]

3

1

2

0

Distance [km]43210

Ray traces 200m

Dep

th [k

m]

Distance [km]

3

1

2

0

43210

Ray traces 1500m

Dep

th [k

m]

Horizon [km]

Horizon for 3 different receiver depths 0

1.8

0.6

1.2

0 0.5 1 1.5 2.52

20 m

200m

1000m

Receiver

Transmitter

17

Ray Propagation)0.1(438.035.1)( 0132.0 Zezn


ARA expected performanceEffective volume

Ongoing simulation studies to optimize detector geometry, and make the best use of the 2.5km ice target.

17 18 19 20

Neutrino Energy [eV]

Effec

tive

volu

me

[km

3 sr]

10

100

1000


The Game Plan

Establish cosmogenic

neutrino fluxes

Resolve Energy

Spectrum

Neutrino direction

Reconstruction

Flavor analysis

Particle physics

~10 ~1000

Small set of well established events.Coarse energy reco

Energy reconstruction by denser sampling of

each event

Angular resolution of less than 0.1 rad

Events/year


GZK

ARA expected performancedetector sensitivities

RICE 2006

ARA (3 years)

ANITA (3 flights)

Pure Iron UHECR

IceCube (3 years)

Auger Tau (3 years)

How strong

should a source

be, for it to be

detected by a

detector


ARA expected performanceReconstruction

Vertex reconstruction :Where in the ice did the Neutrino interact?Using timing information from different antennas.•Distance to vertex (for calorimetry)•Location of Vertex (Background rejection

Neutrino Direction and Energy: Where in space did the Neutrino come from?Combining amplitude and polarization information with Cherenkov cone models.ARA is not optimized for this. Simulated Angular resolution: ~6°


Phase 1: 3 years plan2010-2011 Install testbed

EMI survey away from the station Test ice properties Begin testing station prototypes

Calibration activities Install 3 deep RF Pulsers

Conduct Drilling tests Install 3 Wind turbines for testing

2011-2012 Install ARA in ice station Install Power/comm hub

2012-2013 Install ARA in ice station Install autonomous Power/comm hub

Large array challenges:•Power source •Power and communication distribution•Drilling (size, depth, drilling time)•EMI


Finding the right drillWhy it is a big deal for us

Detector design:• Hole diameter impacts antennas design • Wet/dry hole• Depth possibilities:

Shadowing effect Deeper is betterIce Temperature Shallower is better

Logistics:• Drill will have to be moved several times a season• Short setup and drilling time• Simple operation

Cost & schedule:• Use existing technologies.• Keep it fast, save and simple


• Cutter head drill hole-shavings extracted using compressed air

• Extra compressors required at SP altitude

• Lots of cargo to get it to the Pole

• Dry, 4 inch hole

• Deepest holes achieved: ~60 m in less than 1 hour.

• Limited by air pressure leakage through the firn

• Cutter head drill hole-shavings extracted using compressed air

• Extra compressors required at SP altitude

• Lots of cargo to get it to the Pole

• Dry, 4 inch hole

• Deepest holes achieved: ~60 m in less than 1 hour.

• Limited by air pressure leakage through the firn

This season’s on ice achievementsDrill Test 1 : Rapid Air Movement


• Carried on three sleds pulled by tractor • 0.5 – 1m per minute ( 200m in ~1/2 day )• 6” hole• Wet hole- must be pumped out or electronic made watertight• Deepest hole drilled ~160 m

• Carried on three sleds pulled by tractor • 0.5 – 1m per minute ( 200m in ~1/2 day )• 6” hole• Wet hole- must be pumped out or electronic made watertight• Deepest hole drilled ~160 m

ARA hot water drill sleds Drill in Operation

This season’s on ice achievementsDrill Test 2 : Hot water drill


• Three different turbines were installed.• Measuring and comparing wind speed, power yield.•Weather effects to be evaluated next summer.

This season’s on ice achievementsWind Turbines


Antennas design:• 150-850 MHz• Designed to fit in 15cm holes• Azimuthal symmetric Cables pass through antenna. No shadowing.

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ARA’s prototype antennas

Ice Properties: Attenuation length

• Depends on ice temperature. Colder ice at the top.• Reflection Studies (2004) (Down to bedrock, 200-

700MHz): “normalize” average attenuation according to temperature profile.

Besson et al. J.Glaciology, 51,173,231,2005

• 2 on going “point to point” analyses using NARC/RICE and the new deep pulse.

(34Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 34

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Neutrino interact in ice showers

dCRdP

Charge asymmetry: 20%-30% more electrons than positrons.

Moliere Radius in Ice ~ 10 cm:This is a characteristic transverse dimension of EM showers. <<RMoliere (optical), random phases P N >>RMoliere (RF), coherent P N2

HadronicEM

Askaryan effect

Vast majority of shower particles are in the low E regime dominates by EM interaction with matter

Less Positrons:Positron in shower annihilate with electrons in matter e+ +e- ggPositron in shower Bhabha scattered on electrons in matter e+e- e+e-

More electrons:Gammas in shower Compton scattered on electron in matter e- + g e- +g

Many e-,e+, g Interact with matter Excess of electrons Cherenkov radiation Coherent for wavelength

larger than shower dimensions


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Measurements of the Askaryan effect

Typical pulse profileStrong <1ns pulse 200 V/mSimulated curve normalized to experimental results

Expected shower profiled verified

Expected polarization verified (100% linear) Coherence verified.

New Results, for ANITA calibration – in Ice

SaltIce

D.Sa

lzbe

rg, P

. Gor

ham

et a

l.

• Were preformed at SLAC (Saltzberg, Gorham et al. 2000-2006) on variety of mediums (sand, salt, ice)

• 3 Gev electrons are dumped into target and produce EM showers.

• Array of antennas surrounding the target Measures the RF output

Results:

RF pulses were correlated with presence of shower


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Ice Properties: Index Of Refraction

• RICE Measurements (2004, Down to 150 m, 200MHz-1GHz)

• Ice Core Measurements (…-1983, down to 237 meters)

Kravchenko et al. J.Glaciology, 5

0,1

71

,20

04

)0.1(438.035.1)( 0132.0 Zezn

1.77

Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA37

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Ray tracing from pulser to SATRA

Sourceat -250m

Bottom antenna-35m

Top antenna -5m

Dep

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


http://wiki.icecube.wisc.edu/images/6/6a/Sally-satra_string_16.png

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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 ns Simulated results=14 ns


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Based on set of hit time differences between antennasand between primary and secondary hits on the same antenna,a limit on the index of refraction model can be obtained.Systematics taken into account: n_deep, Geometry, timing resolution, WF features

n_c

n_sh

allo

w


hagar landsman, university of wisconsin, madison

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