Next Generation neutrino detector in
the South Pole
Askaryan Under-Ice Radio Array
Hagar Landsman,
University of Wisconsin, Madison
Outline
Askaryan
Askaryan Effect and neutrino detection
Under ice
Why Ice? Why Radio?
Radio
Radio detection
Array
Experiment Design and prospective
Tribute to ATLAS@LHC.CERN
The
IceFuture:
Cube ~ 1km
Hybrid Detector ~10 km
25 m
45 m
Quest for UHE neutrinos
• GZK Cut-off p+gCMB
– No cosmic rays from
proton above 1020 eV
– As a by-product –
neutrino flux
– A non detection will be
even more exciting
• Point Sources of
neutrinos
• Dark matter
Why so big?
• To detect 10 GZK events/year, a detection
volume of 100 km3 ice is needed.
• A larger detector requires a more efficient and
less costly technology.
• Alternative options include radio and acoustic
detection.
Askaryan effect
Neutrino interact in ice
 showers
 Many e-,e+, g
 Interact with matter
 Excess of electrons
 Cherenkov radiation
Coherent for wavelength
larger than shower
dimensions
dPCR  d
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
Hadronic (initiated by all  flavors)
EM (initiated by an electron, from e)
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-  gg
Positron 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
Charge asymmetry: 20%-30% more
electrons than positrons.
LPM effect
Landau-Pomeranchuk-Migdal
 As the energy increases, the multiplicity of the shower increases and the
charge asymmetry increases.
 As the energy increases, mean free path of electrons is larger then
atomic spacing (~1 PeV) (LPM effect).
 Cross section for pair production and bremsstrahlung decreases
 longer, lower multiplicity showers
The Neutrino Energy threshold for LPM is different for Hadronic and for EM
showers
 Large multiplicity of hadronic showers. Showers from EeV hadrons have high
multiplicity ~50-100 particles.
 Photons from short lived hadrons
 Very few E>100 EeV neutrinos that initiate Hadronic showers will have LPM
 In high energy, Hadronic showers dominate
 Some flavor identification ability
Measurements of the Askaryan effect
• Were preformed at SLAC (Saltzberg, Gorham et al. 2000-2006) on
variety of mediums (sand, salt, ice)
• 3 Gev photons are dumped into target and produce EM showers.
• Array of antennas surrounding the target Measures the RF output
 RF pulses were correlated with presence of shower
Salt
Ice
 Expected shower profiled verified
 Expected polarization verified (100% linear)
 Coherence verified.
New Results, for ANITA calibration – in Ice
Typical pulse profile
Strong <1ns pulse
200 V/m
Simulated curve
normalized to
experimental results
D.Salzberg, P. Gorham et al.
Results:
Long attenuation - Radio ~1km
-
No scattering for Radio In ice.
-
A lot of it.
-
Free to use.
-
South pole is isolated. RF quiet.
-
Antennas are cheaper and more
robust than PMTs.
-
-
Optical attenuation in ice 100m
No need to drill wide holes
lower drilling cost of deployment
w.r.t optical detectors
1016 - ~1023 eV
Astro-ph/9510119 P.B.Price 1995
-
Effective Volume per Module (Km3)
Why Ice? Why Radio?
1012
1013
1014
1015
1016
Energy (eV)
Effective volume per detector element
for e induced cascades
1017
IceCube
ANITA
•Pressure vessel
•Connectors
•Mainboard
•DAQ
•Cables
•Holes
LABRADOR chip:
•low power consumption
•low deadtime
•large bandwidth
•cold rated
RICE
Antennas
Data analysis
Electronics and control
KU
University of
Maryland
University of
Delaware
University of
Hawaii
Kansas
University
Penn State
University
University of
Wisconsin - Madison
surface
junction
box
Counting
house
Deployment in the
coming season
Each unit is composed of :
− 1 Digital Radio Module (DRM) – Electronics
− 4 Antennas
− 1 calibration units
Signal conditioning and amplification happen at the
front end, signal is digitized and triggers formed in
DRM
Co-Deployment on spare breakouts on IceCube cables
(top/bottom) or on a special breakout
Depth possibilities:
−Top
(1450 m) : Colder Ice, less volume
−Bottom (2450 m) : Warmer Ice, more volume
−Dust layer : less efficient spot for ~400nm
Not to scale!
RF attenuation is longer at colder ice
Deployment in the coming season
Planning to deploy 4 units.
with IceCube.
Start mid December 2006
3rd hole (1400m)
8th hole (1400m)
9th hole (250m)
10th hole(1400m)
11th hole(250m) spare
IceCube Holes Map for 2006-2007
Radio Module
Digital Optical
Module(DRM)
(DOM)
6 Penetrators:
To
antenna
4 Antennas
1 Surface cable
1 Calibration unit
TRACR Board
Trigger Reduction and Comm for Radio
Data processing, reduction, interface to MB
MB (Mainboard)
Communication, timing, connection to IC DAQ
infrastructure,
Shielding separates noisy components
ROBUST Board
To
antenna
ReadOut Board UHF Sampling and Triggering
Digitizer card
SHORT Boards
Surf High Occupancy RF Trigger Trigger banding
Multiple bandwidth trigger
16 combinations of
triggers:
− 4 antennas
− 4 bandwidth on each antenna
− Trigger condition will be tuned to
maximize data rates within the
cable bandwidth.
− Remove a noisy frequency
Dipole Antennas
17 cm
Antennas
IceCube DOM
ROBUST
TRACR
DOM-MB
Metal Plate
DRM electronics
IceCube DOM
DAQ layout
DRM
DRM
DRM
Decrease rates to fit surface cable:
L0 - Single frequency band trigger (SHORT, ROBUST)
L1 – Multiple bands and multiple antennas (ROBUST)
L2 – Higher level analysis filter-FFT (TRACR)
Decrease rates to fit data storage/satellite volume
L3 - Data quality on surface (HUB)
L4 - Send over satellite? Save to tapes?
3.5 Kbytes
25 Hz
HUB
3.5 Kbytes
25 Hz
3.5 Kbytes
25 Hz
Time Calibration
QA
Monitoring
Control
Time order
Sat.
Offline
processor
Event Trigger
Analysis
Our Mission:
• Build intermediate detector with improved effective
volume over RICE, using IceCube infrastructure
• Experiment new Antenna and electronic design
• Further map the south pole ice radio properties
• Check interference between IceCube and AURA
• Adapt form factors for narrower holes drilled exclusively
for radio.
• Correlate events with RICE
• On the way to a super-duper-hybrid GZK neutrino detector
Picture by Mark Krasberg
Backup Slides
Askaryan Signal
Electric Field angular distribution
Astro-ph/9901278 Alvarez-Muniz, Vazquez, Zas 1999
Cherenkov angle=55.8o
Electric Field frequency spectrum
Askaryan Signal
Electric Field angular distribution
Astro-ph/9901278 Alvarez-Muniz, Vazquez, Zas 1999
Cherenkov angle=55.8o
Electric Field frequency spectrum
Excpected Signal
surface generated event as
measured by RICE detectors at
different depths
Reflection studies @S.Pole, Jan. 2004 - S. Barwick
Field Attenuation Length (m)
2000
T-50C
1500
1000
Tave
500
0
0
100
200
300
400
500
Freq (MHz)
600
700
800
•made surveys of rf
properties of the
ice at the South
Pole
•set most stringent
limits on the
neutrino flux from
10^16 to 10^18 eV
•set limits on low
scale gravity,
magnetic
monopoles and
other exotica
Note: RICE uses a 95% C.L. upper limit
a larger, more technologically sophisticated array is needed for a
neutrino observation… current hardware too expensive to scale up
See latest results astro-ph/0601148
19 channels in depths 100m - 300m
Measurements of the Askaryan effect
Typical pulse profile
Strong <1ns pulse
2 GHz
Measurements of the Askaryan effect
SLAC T444 (2000) in sand
Sand
Filed strength measure by….
E= prop to shower E 