next generation neutrino detector in the south pole hagar landsman, university of wisconsin, madison...
TRANSCRIPT
Next Generation neutrino detector in the South Pole
Hagar Landsman, University of Wisconsin, Madison
Askaryan Under-Ice Radio Array
Outline
Askaryan Effect and neutrino detection
Why Ice? Why Radio?
Radio detection
Experiment Design and prospective
Askaryan
Under ice
Radio
Array
Quest for UHE neutrinos • GZK Cut-off p+CMB
– 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.
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
Hadronic (initiated by all flavors)EM (initiated by an electron, from e)
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- 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- + e- +
Many e-,e+, Interact with matter Excess of electrons Cherenkov radiation Coherent for wavelength larger than shower dimensions
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
LPM effectLandau-Pomeranchuk-Migdal
In high energy, Hadronic showers dominate
Some flavor identification ability
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.S
alzb
erg,
P. G
orha
m e
t al.
• 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
Results:
RF pulses were correlated with presence of shower
Why Ice? Why Radio?
- Long attenuation - Radio ~1km- Optical attenuation in ice 100m
- 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.
- No need to drill wide holes lower drilling cost of deployment w.r.t optical detectors
1016 - ~1023 eV
optical
Radio
Acou
stic
Ice, n
o bubbles (1.5-2
.5 km)
Ice, bubbles (0.9 km)W
ater (Baika
l 1km
)
Eff
ect
ive
Vo
lum
e p
er
Mo
du
le (
Km
3 )Energy (eV)
1012 1013 1014 1015 1016
Astro-ph/9510119 P
.B.P
rice 1995
1017
Effective volume per detector element for e induced cascades
IceCube•Pressure vessel•Connectors•Mainboard•DAQ•Cables•Holes
ANITA LABRADOR chip:•low power consumption•low deadtime•large bandwidth•cold rated
RICE Antennas
Data analysisElectronics and control
KU
University of Maryland
University of Delaware
University of Hawaii
KansasUniversity
University of Wisconsin - Madison
Penn State University
Deployment in thecoming seasonsurface
junction box
Counting house
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
RF attenuation is longer at colder ice
Not to scale!
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
Toantenna
Toantenna
To
antenna
To
surface
ToCalibrationunitTo
antenna
Shielding separates noisy components
6 Penetrators: 4 Antennas 1 Surface cable 1 Calibration unit
TRACR BoardTrigger Reduction and Comm for RadioData processing, reduction, interface to MB
ROBUST BoardReadOut Board UHF Sampling and Triggering Digitizer card
SHORT BoardsSurf High Occupancy RF Trigger Trigger banding
MB (Mainboard)Communication, timing, connection to IC DAQ infrastructure,
Digital Radio Module (DRM)Digital Optical Module (DOM)
Multiple bandwidth trigger16 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
TRACR
DOM-MB
Metal Plate
Antennas
DRM electronics
ROBUST
Dipole AntennasIceCube DOM
IceCube DOM
17 cm
Time CalibrationQA
MonitoringControl
Time order
Event TriggerAnalysis
Sat.
Data
3.5 Kbytes25 Hz
3.5 Kbytes25 Hz
3.5 Kbytes25 Hz
DRM DRM
HUB
time
Data
Decrease rates to fit data storage/satellite volumeL3 - Data quality on surface (HUB)L4 - Send over satellite? Save to tapes?
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)
DRM
Offline processor
DAQ layout
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
Pic
ture
by
Mar
k K
rasb
erg
Backup Slides
Askaryan Signal
Cherenkov angle=55.8o
Electric Field angular distributionElectric Field frequency spectrum
Astro-ph/9901278 A
lvarez-Muniz, V
azquez, Zas 1999
Askaryan Signal
Cherenkov angle=55.8o
Electric Field angular distributionElectric Field frequency spectrum
Astro-ph/9901278 A
lvarez-Muniz, V
azquez, Zas 1999
Excpected Signal
surface generated event as measured by RICE detectors at different depths
0
500
1000
1500
2000
0 100 200 300 400 500 600 700 800
Reflection studies @S.Pole, Jan. 2004 - S. Barwick
Fie
ld A
tten
uatio
n Le
ngth
(m
)
Freq (MHz)
Tave
T-50C
a larger, more technologically sophisticated array is needed for a neutrino observation… current hardware too expensive to scale up
•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
See latest results astro-ph/0601148 19 channels in depths 100m - 300m
2 GHz
Measurements of the Askaryan effect
Typical pulse profileStrong <1ns pulse
Measurements of the Askaryan effect
SLAC T444 (2000) in sand
Sand
Filed strength measure by….
E= prop to shower E