englacial arrays for detection of cosmogenic neutrinos at the south pole icecube radio ...
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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 - PowerPoint PPT PresentationTRANSCRIPT
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)
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 3
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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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 4
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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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 5
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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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 6
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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 7
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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 10
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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 11
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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 12
•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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 13
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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 14
• 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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 15
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
Dept
h [k
m]
3
1
2
0
Distance [km]43210
Ray traces 200m
Dept
h [k
m]
Distance [km]
3
1
2
0
43210
Ray traces 1500m
Dept
h [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
1000mReceiver
Transmitter
17
Ray Propagation)0.1(438.035.1)( 0132.0 Zezn
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 18
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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 19
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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 24
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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 25
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°
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 26
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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 27
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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 28
• 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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 29
• 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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 30
• 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
Hagar Landsman IceCube RF extension and ARA APS 2011, Anaheim,CA 31
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.
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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
lzber
g, 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, 50,171,2004
)0.1(438.035.1)( 0132.0 Zezn
1.77
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Ray tracing from pulser to SATRA
Sourceat -250m
Bottom antenna-35m
Top antenna -5m
Dept
h [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 nsSimulated 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
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