Beyond IceCube the South Pole

1
Beyond IceCube _at_ the South Pole

• Outline
• Introduction Optical vs. Radio Acoustic
• Moving to the GZK scale En gt 1016 eV
  sensitivities
• Radio
• RICE
• Near-term future ideas
• ROCSTAR/DRM
• Surface array
• Acoustic
• Near-term future ideas
• SPATS
• Capabilities of a combined IceCube, Radio and
  Acoustic (IRA) detector
• Comments on IRA nt sensitivities
• Conclusions

2
Optical vs. Radio Acoustic

• IceCube has been optimized for energies in the
  range between roughly 1 TeV and 10 PeV
• The buried array relies on one type of detection
  channel optical
• Cherenkov light from UHE n-induced charged
  particles
• latt 30m requires high module density
• IceCube has r 5000/km3
• To get sufficient statistics at higher energy
  scales (e.g., GZK scale), where one needs a
  fiducial volume closer to 100-1000 km3, need
  technology that is practical at lower module
  densities

3
Optical vs. Radio Acoustic

• Happily, ice is also well-suited for detection of
  UHE neutrino-induced radio and acoustic signals
• Cherenkov radio signals
• 1km attenuation length
• proven technology (RICE)
• Acoustic signals
• 10km attenuation length
• potentially very quiet environment (vs., e.g.,
  ocean)
• Coincident event capture offers many benefits
• Therefore, in this talk we will focus on efforts
  using ice at the South Pole
• Will not cover other very interesting and
  promising radio and acoustic efforts, like ANITA,
  SalSA, SAUND,

4
Beyond IceCube _at_ the South Pole

• Outline
• Introduction Optical vs. Radio Acoustic
• Moving to the GZK scale En gt 1016 eV
  sensitivities
• Radio
• RICE
• Near-term future ideas
• ROCSTAR/DRM
• Surface array
• Acoustic
• Near-term future ideas
• SPATS
• Capabilities of a combined IceCube, Radio and
  Acoustic (IRA) detector
• Comments on IRA nt sensitivities
• Conclusions

5
Focus on Guaranteed UHE Neutrinos

• GZK flux models

• Roughly speaking, depending on various
  assumptions, to detect one GZK n/yr at 1016-19 eV
  requires Veff 4-50 km3
• See, e.g., Engel, Seckel and Stanev, Phys. Rev.
  D64 (2001) 093010

From Gorham et al., Phys. Rev. D72 (2005) 023002
6
Saltzberg, astro/ph 0501364
7
Beyond IceCube _at_ the South Pole

• Outline
• Introduction Optical vs. Radio Acoustic
• Moving to the GZK scale En gt 1016 eV
  sensitivities
• Radio
• RICE
• Near-term future ideas
• ROCSTAR/DRM
• Surface array
• Acoustic
• Near-term future ideas
• SPATS
• Capabilities of a combined IceCube, Radio and
  Acoustic (IRA) detector
• Comments on IRA nt sensitivities
• Conclusions

8
UHE Neutrino Radio Detection RICE

• Design
• 20-channel array of dipole antennas
• 100-300m depths
• 200x200x200 m3 deployment volume
• Analog readout into surface digitizers

10 cm
5 m
9
UHE Neutrino Radio Detection RICE

• Results (Kravchenko et al., astro-ph/0601148)
• 1999-2005 RICE livetime of 20500 hrs
  (Vefflivetime 1-10 km3?yr?sr _at_ 1017-19 eV)

• (Results from GLUE, ANITA, FORTE in the
  literature at this workshop)

10
Beyond IceCube _at_ the South Pole

• Outline
• Introduction Optical vs. Radio Acoustic
• Moving to the GZK scale En gt 1016 eV
  sensitivities
• Radio
• RICE
• Near-term future ideas
• ROCSTAR/DRM
• Surface array
• Acoustic
• Near-term future ideas
• SPATS
• Capabilities of a combined IceCube, Radio and
  Acoustic (IRA) detector
• Comments on IRA nt sensitivities
• Conclusions

11
New Ideas for Radio at the South Pole

• ROCSTAR
• Retrofitted OptiCal SysTem Adapted for Radio
• Piggybacks on existing IceCube DOMs

• Use Main Board as-is for timing and power
• Replace flasher board with radio digitizer
  board to process all radio-related signals
• use pre-existing interface bus to MB
• Remove PMT, HV stuff, etc.
• Rename it DRM for Digital Radio Module

12
Possible ROCSTAR Node Configuration
50m
13
Possible ROCSTAR Block Diagram
Antennas
Local coincidence triggering
14
ROCSTAR Deployment Depth

• Optical-Radio coincident event rate can be
  substantial
• Preferable to deploy close to surface, but
  temperature still reasonably cold (-42C) at 1450
  m
• Simulations needed to optimize geometry

ROCSTAR Nodes (70)
15
ROCSTAR

• Advantages
• Uses existing hardware with minimal modification
  to significantly enlarge radio array at the South
  Pole
• Straightforward to integrate into existing
  optical array data acquisition system to make
  functioning hybrid detector and see coincident
  events
• Minimal impact on IceCube deployments
• Disadvantages
• Geometry somewhat inflexible, not optimal
• Use of existing hardware imposes some constraints
  on design of in-ice radio electronics (probably
  not severe)

16
Beyond IceCube _at_ the South Pole

• Outline
• Introduction Optical vs. Radio Acoustic
• Moving to the GZK scale En gt 1016 eV
  sensitivities
• Radio
• RICE
• Near-term future ideas
• ROCSTAR/DRM
• Surface array
• Acoustic
• Near-term future ideas
• SPATS
• Capabilities of a combined IceCube, Radio and
  Acoustic (IRA) detector
• Comments on IRA nt sensitivities
• Conclusions

17
Surface Array

• Calibration of UHE neutrino detectors is tricky
  due to lack of a test beam
• IceCube approach
• in-situ light sources (LEDs, lasers) to mimic
  cascade events up to 10 PeV
• cosmic-ray muons and atmospheric nm-induced muons
  up to about 10 TeV
• Radio and Acoustic approaches
• in-situ (or nearby) transmitters
• New idea (Seckel Seunarine)
• use Askaryan radio pulse produced when cosmic-ray
  air shower cores particles hit the earth (or the
  ice upon it)
• comprise a few of the energy of the air shower

18
Surface Array

• Use an array of radio antennas near the surface
  at the Pole

• Trigger with IceTop, the air shower array atop
  the IceCube buried array
• With Epgt3PeV, a 30 m 30 m array would see 1
  ev/hr
• Not just for radio array calibration
• cosmic-ray composition studies may be possible
  too
• RICE might be able to do this
• More simulation work needed

19
Beyond IceCube _at_ the South Pole

• Outline
• Introduction Optical vs. Radio Acoustic
• Moving to the GZK scale En gt 1016 eV
  sensitivities
• Radio
• RICE
• Near-term future ideas
• ROCSTAR/DRM
• Surface array
• Acoustic
• Near-term future ideas
• SPATS
• Capabilities of a combined IceCube, Radio and
  Acoustic (IRA) detector
• Comments on IRA nt sensitivities
• Conclusions

20
UHE Neutrino-Induced Acoustic Signals

• A n-induced cascade will produce localized
  heating in the medium, creating a pressure wave
• Detect sound, peaked at 40kHz, with detectors
  distributed in the ice at the South Pole
• Short-term issues
• absorption length
• probably large must measure
• refraction
• background noise
• probably small must measure
• man-made on surface
• slip-stick of glacier on bedrock
• micro cracks
• N.B. No noise from dolpins, ships, wind, waves,

S. Boeser/DESY
21
UHE Neutrino-Induced Acoustic Signals

• Predicted attenuation length for sound in ice
  looks very promising (plot below is for 10kHz)

Depth variation is due to change in temperature
of the ice at Pole.
J. Vandenbroucke/ARENA 2005
22
Acoustic Detection Contours in Ice
Contours for Pthr 9 mPa raw discriminator, no
filter
longitudinal coord.
J. Vandenbroucke/ARENA 2005
lateral coord.
23
Acoustic Signals SPATS

• South Pole Acoustic Test System
• Purpose measure
• noise
• refraction
• attenuation length
• Design for 06/07 season
• Deploy in 3 IceCube holes at 400m depth
• 7 acoustic stages per hole
• sensor and transmitter
• 3 surface interface boxes
• power, network interface
• 1 master CPU
• network interface, GPS timestamp

24
SPATS Module
Modules at DESY/Zeuthen
Sensor Module
One Full Module
25
After SPATS

• If the measurements made with SPATS during the
  2006/2007 season at the South Pole are
  encouraging, the next step will be to plan and
  hopefully build a much larger device
• 100 km3 effective volume at GZK energies
• 100 strings on 1 km spacing grid
• 300 receivers per string (co-deployed with radio)

26
Beyond IceCube _at_ the South Pole

• Outline
• Introduction Optical vs. Radio Acoustic
• Moving to the GZK scale En gt 1016 eV
  sensitivities
• Radio
• RICE
• Near-term future ideas
• ROCSTAR/DRM
• Surface array
• Acoustic
• Near-term future ideas
• SPATS
• Capabilities of a combined IceCube, Radio and
  Acoustic (IRA) detector
• Comments on IRA nt sensitivities
• Conclusions

27
Hybrid IRA Detector

• As in HEP and Auger, using more than one
  detection technique to view the same fiducial
  volume is highly advantageous
• Detecting events in coincidence between 2-3
  methods is more convincing than detections with 1
  method alone
• Coincident events allow calibration/cross-checks
  one method relative to the others
• Hybrid reconstruction will give superior energy
  and direction resolution than with one method, or
  at least will allow reconstruction of coincident
  events that cannot be reconstructed with one
  method alone
• Good complementarity
• Overlapping sensitivities in energies around
  10-100PeV
• At lower energies, optical device is better
• At higher energies, radio/acoustic are better
• The resulting hybrid detector would have
  sensitivity to neutrinos over about 10 orders of
  magnitude in energy!

Halzen Hooper IceCube Plus JCAP 01 (2004) 002
28
Hybrid IceCubeRadioAcoustic

• Simulations have been made of a hybrid detector
  consisting of
• IceCube plus 13 outrigger strings ()
• 91 additional radio/acoustic holes with 1 km
  spacing (o)
• 5 radio receivers 200-600 m
• 300 acoustic receivers, 5-1500 m
• 2p acceptance, hadronic shower only (LPM
  stretches EM showers), Esh 0.2E?

See D. Besson et al., ICRC 2005
29
Hybrid IRA Simulation

• Result
• Veff at Egt1017 eV increased by a factor of 5-25
  over IceCube alone (Veff gt 100km3)
• 20 GZK n events/year

• Notes
• ESS flux, Gandhi ss, ?? 0.7
• For R, A, RA
• all flavors
• NC and CC
• For O
• only m

Veff (km3)
IIceCube RRadio AAcoustic (GZK ns/yr)
Log10En/eV
30
Some Comments on UHE nt with IRA

• High energy tau neutrinos are especially good
  candidates for coincident event capture Veff
  increases by a lot
• Double bangs
• one bang in radio/acoustic array, one in optical
  array
• Lollipops
• detect tau lepton track in optical array, tau
  decay cascade in radio/acoustic array
• Sugardaddies (see talk by T. DeYoung)
• detect tau lepton creation in radio/acoustic, tau
  decay to muon in optical array

31
Beyond IceCube _at_ the South Pole

• Outline
• Introduction Optical vs. Radio Acoustic
• Moving to the GZK scale En gt 1016 eV
  sensitivities
• Radio
• RICE
• Near-term future ideas
• ROCSTAR/DRM
• Surface array
• Acoustic
• Near-term future ideas
• SPATS
• Capabilities of a combined IceCube, Radio and
  Acoustic (IRA) detector
• Comments on IRA nt sensitivities
• Conclusions

32
Conclusions

• We believe we can get to effective volumes large
  enough to detect GZK neutrinos at the South Pole
  using radio and/or acoustic techniques
• The cost of drilling (shallower and narrower)
  holes and of the individual radio and acoustic
  elements is very reasonable (very roughly,
  30k/hole for drilling, 20k for sensors)
• Operating optical, radio and/or acoustic
  detectors in coincidence will not only produce
  more convincing individual events, but also
  extend the reach and accuracy compared to any one
  detector alone