IceCube: Multiwavelength Approach to Transient Neutrino Point Source Candidates
1. Introduction 2. IceCube Detector 3. Neutrino Detection Principles 4. Status of the Construction...
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Transcript of 1. Introduction 2. IceCube Detector 3. Neutrino Detection Principles 4. Status of the Construction...
1. Introduction2. IceCube Detector3. Neutrino Detection Principles4. Status of the Construction and Performance5. Summary
IceCubeneutrino telescope@SouthPole
- a new window on the universe
Joanna Kiryluk LBNL/UC Berkeley
UHE
Cosmic Rays
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p+ γ → Δ → π + n→ ...GZK cutoffGreisen, ZatsepinAnd Kuzmin (1966)
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What’s the origin of Cosmic Rays with E up to 1020 eV ?The puzzle unresolved almost a century after CR discovery
?SNR
- do not point back to the source
protons: directions scrambled by magnetic
fields -rays : straight-line
propagation
Multi-Messenger AstronomyWhere do UHE cosmic rays come from?
protons, -rays & neutrinos as probes of the high-energy Universe
- do not point back to the source
but reprocessed in the sources (difficult to prove that they are associate with CR); extragalactic backgrounds absorb E>TeV
Multi-Messenger AstronomyWhere do UHE cosmic rays come from?
protons, -rays & neutrinos as probes of the high-energy Universe
protons: directions scrambled by magnetic
fields -rays : straight-line
propagation
Neutrinos:Neutrinos: straight-line propagation, unabsorbed, but difficult to detect
Expected n flux from galactic point sources, example SNR: RXJ 1713-3946
Christian Stegmann et al. , J.Phys.Conf.Serv.60 (2007) 243
€
p+ γ → n + π +
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π → μ+υμ
→ {e + υ μ + υ e} + υ μ
cosmic rays interact with the microwave
background
cosmic rays disappear, neutrinos appear
NeutrinosfromGZKinteractions
Expect ~ 1 event per km2 per year
GZK neutrinos - very low but guaranteed flux (GZK CRs exist!)
(Ultra-) high-energy neutrino detectors
Neutrino telescopes:Primarily aimed at > TeV μ, e.g. IceCube /AMANDA, Antares … Also sensitive to PeV, EeV , but limited area
New directions with effort to detect:Giant air showers detectors sensitive to ~EeV e.g. AugerRadio detection - threshold in EeV range , e.g. Anita
Extraterrestrial neutrinos - discovery potential!
The only confirmed extraterrestrial low energy neutrino sources detected so far are the Sun and the supernova SN1987A
USA: Bartol Research Institute, Delaware Pennsylvania State University UC Berkeley UC Irvine Clark-Atlanta University University of Maryland IAS, Princeton University of Wisconsin-Madison University of Wisconsin-River Falls Lawrence Berkeley National Lab. University of Kansas Southern University and A&M
College, Baton RougeUniversity of Alaska, Anchorage
Sweden: Uppsala Universitet Stockholm Universitet
UK: Imperial College,
London Oxford University
Netherlands: Utrecht University Belgium:
Université Libre de Bruxelles
Vrije Universiteit Brussel Universiteit Gent Université de Mons-Hainaut
Germany: Universität Mainz DESY-Zeuthen Universität Dortmund Universität Wuppertal Universität Berlin MPI Heidelberg RWTH Aachen
Japan: Chiba university
New Zealand: University of
Canterbury
THE ICECUBE COLLABORATION
33 institutions, ~250 members http://icecube.wisc.edu
ANTARCTICAAmundsen-Scott Station
Science potential with IceCube is vast:
Neutrino point source search (μ Diffuse searches ( e, μ and more sensitive if there are more sources
IceCube physics topics
Atmospheric neutrinos Cosmic Ray (C.R.) composition Supernova (SN) Gamma Ray Bursts Search for exotic particles and new physics.
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http://www.sciencemag.org/content/vol315/issue5808
Vol 315 (2007)
The IceCube Detector
Counting House
1450 m
2450 m
AMANDA
IceTop Surface air shower array
InIce 70+ strings, each with 60
digital optical modules (DOM)
17 m between modules
125 m string separation
Instrumenting 1km3 of Antarctic Iceto detect extraterrestrial neutrinos
IceCube will detect neutrinos of all flavors at energies from 1011 eV to 1020 eV
Digital Optical Module (DOM)
DOM - a complete data acquisition system: - internal digitization and time stamping the photonic signals from the PMT- can perform PMT gain and time calibration- transmitting digital data to the surface
PMT
MainBoard
Main Board (most of electronics)- PMT output collected with fast waveform digitizer chips that sample the signal 128 times at 200-700 MSPS - PMT signal is fed into 3 parallel 10-bit ADC with a nominal gain ratios 0.25:2:16. Combined they provide wide dynamic range from single p.e. to thousands p.e.
Time Resolution from LED flashers
Method: flash an LED on a DOM and measure the arrival time of light reaching a nearby DOM
RMS variation of time delay measured with flashers for 59 DOM pairs on one string.
For most of the DOMs resolution better than 2 ns
DOM 51
DOM 52
DOM 53
DOM 54
Photon arrival time delay at DOM 52 when DOM 53 is flashing.
Muon neutrino Electron neutrino
Phototubes
(km long) Track:
+ increased detection volume
+ μ points along μ, i.e. to source
- cosmic ray μ background
- ok energy measured
Cascade: e-m or hadronic showers -must be in detector- μ background (brems’ng)- limited pointing capability + good energy measurement
Neutrinos: How do we see them?
Energy Res. : log(E)~0.3Angular Res.: 0.8 -2 deg
Neutrinos Signature (Simulations)
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E = 375 TeV
Energy Res. log(E)~0.1-0.2Poor Angular Resolution
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+N+...
+hadrons
Muon neutrino Electron neutrino Tau neutrino
a) Eµ=10 TeV ~ 90 hits
b) Eµ=6 PeV ~1000 hits
E = 10 PeV
Double-bang signature above ~ 1 PeVVery low backgroundPointing capability
E ~ dE/dx, E> 1 TeV
Origin of the neutrinos observed in the detector
M.Kowalski [astro-ph/0505506]
atmospheric neutrinos (mostly μ) dN/dE~E-3.7
neutrinos from charm decayIn the atmosphere dN/dE~ E-2.8
astrophysical neutrinos dN/dE~E-2.0 (model)
signal
Extraterrestrial Neutrinos: Signals and backgrounds
Low energy: Distinguish: - μ (CR vs ) by their direction- (atmospheric vs extrater.) by energy
Above 105 TeV - small μ and bg produced in CR interactions with the Earth atmosphere.
Distinguish flavor by their topology
High energy:
Neutrinos (all flavors) interact in(or close to) the detector via:Muon channel:
Cascade channel:
€
e(τ ) + N → e(τ ) + X (CC)ν e(μ ,τ ) + N →ν e(μ ,τ ) + X (NC)
€
μ + N → μ + X (CC)
AMANDA
IceCube
Skiway
Amundsen-Scott South Pole Station
Geographic South Pole
IceCube at the South Pole
Drill Site Counting House
Getting there is half the fun
New C-17 Old C-141 (photo by RGS)
Transportation upgrades to Antartica….
Schedule and Logistics
The new South-Pole station
Can work from December to mid-February Logistics are a huge concern Power - expensive! 3 winterover scientists operate and maintain instrument during winter Weather is always a factor
Field team deals very well with issues and harsh conditions
Hotwater drill system
Drill tower
Hose reel
DOMs
Hole Drilling
Design goal: 40 hours to drill a hole
36 h
Successfully used for three holes. Expected to save about 2 holesper season.
2007: Independent firn drillD
ep
th (
m)
Time
2500 m deep, 60 cm dia. holes 5 Megawatt hot water drill Speeds to 2.2 m/minute
IceCube Deployments to Date AMANDA
21
3029
40
50
3938
49
59
4647
48
5857
6667
74
65
73
78
56
72
2004-2005
1 string deployedFirst dataastro-ph/0604450
2005-2006
8 string deployed
2006-2007
13 strings deployed
1+8+13 = 22 strings to dateGoal >=14 strings/season
Completion by 2011.
More than 25 % of full detector installed.
1424 sensors deployed, and 1403 sensors (98.5%) are commissioned and being used
Comparison to AMANDA-II: 85 of 677 sensors (12.5%) are not usable for technical reasons
April 29 2007 (commissioning)
IceDust layer (low rate)
2007 13-strings Deployment Physics Run - started May 2007 Updated DAQ, triggers, monitoring system
1450m 2450m 0 50m
Measurements: in-situ light sources, atmospheric muons and Dust Loggers (records dust layers with cm resolution):
Ice Properties: scattering and absorption
Average optical ice parameters:
Dust Logger signal
depth (m)
depth (m)D
OM
Occ
upan
cy
abs~110m@400nmsca~ 20m@400 nm
Scattering length varies from 6 to 30m depending on depth and location of dust layers (deposited by e.g. volcanic events over past thousands of years)
Understanding ice properties - key to modeling IceCube
Probability a DOM is hit in evts that have >7 hits on a string
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Dust Logger
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Bubble Camera - 2007 deployment
DOM 60
Weight Stack
Sphere 1
Sphere 2
String 57
Particle (μ) Tracking
Charged particles emit Cherenkov radiation angle = Cos-1(1/n) = 410
The photons scatter (L ~ 25 m) Some (<10-6) photons are observed in photodetectors We measure points 0-30 meters from the μ track Angular resolution < 10 for long tracks
μNoise
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μ + N → μ + X
bremsstrahlung
pair-creation
e+e-
πphoto-nuclear
μ tracks lose energy by emitting , e+e- pairs and hadronic interactions (via virtual )
DOM
Atmospheric muon neutrinos in 2006 2006 data: 90 days with 9 stringsData selection done online at S. Pole and transferred by satellite North
Neutrino-induced muon candidate
Dust layer
IC-9strings (first) analysis: Atmospheric muon neutrinos in 2006
Reconstructed Zenith Angle (deg)
Contamination at the horizon likely due to mis-reconstructed events (single shower) as being below the horizon.
After cuts: 234 events measured (211 expected from atm. MC) Reconstructed direction
Reconstructed Azimuth Angle (deg)
Horizon
arXiv:0705.1781 [astro-ph]
Event rate: 610 Hz Raw data: 180 GB/day Uptime to date: 92% Events recorded by June 28, 2007 1.65 x 10^9 Continuous data taking …
Sufficient data to observe (diffuse) non-atmospheric neutrinos?
IC-22 run statusMay 23, 2007 - start of IceCube science run
Downgoing muons (background) Azimuth distribution illustrates
detector response.
String Commissioning
pDAQ IC36+Commissioning(95%)
Calibration(Geometry, DOMs)
P&F IC36+Commissioning
Dec Jan Feb Mar April
IC22 Science run IC36+ Science run
IC 36+ verification
FinishLatecomers
IC22 IC36+ Schedule
Current status: Ready to go….winterovers arrive on ice Oct 22!!Bulk of drillers arrive on Oct 31
Future Plans Above ~ 1016 eV, the expected rates in IceCube are small
A ~100 km3 detector is needed to see GZK Protons and have limited range. Only probe sensitive to ‘EHE universe’ > 50 megaparsecs away
Coherent radio and/or acoustic detection of EHE showers may allow for an affordable detector
Summary IceCube construction is well underway
- More than 25% complete.- Completed detector in 2011.
Physics analysis underway.IceCube IC-9 atmospheric muon neutrino resultsIC-22 analyses on-going
Stay tuned!
ANITA
ANITAGondola &
Payload
Antenna array
Overall height ~8m
Solarpanels
Antarctic Impulsive Transient Antenna Experiment
searching for GZK neutrinos with radio
detection in Antarctic iceneutrino
Cascade: ~10m length
air
Ice- radio transparent medium
RFCherenkov
Utilizes Askaryan effect
STATUS: 35 day flight this season 2006/7
~15 days of good data - Haven’t unblinded yet
- Might see a GZK neutrino, if luckyPayload was crunched on landing
Next flight in 2008/9
ARIANNA concept
100 x 100 station array, ~1/2 Teraton
~300m
Ross Ice Shelf, Antarctica
Sensitivity and limits
S. Barwick
ANITA sensitivity, 45 days total:~5 to 30 GZK neutrinos
IceCube: high energy cascades ~1.5-3 GZK events in 3 years
Oscar Blanch-Bigas
Neutrino fluxes - upper limits
Supernova Monitor
Amanda-II
IceCube
0 5 10 sec
Count rates
LMC
AMANDA II:95% of Galaxy
IceCube:Milky Way + LMC
msec time resolution
You are here
Data Acquisition and Trigger
“Full” DAQ software & triggerSelect time regions of interest using
multiplicity, topologyEvents == time windowCollect data for these windows
Data filtering (muon, cascade)Reconstruct eventsSelect interesting events for satellite
transmission
Monitoring, calibration, logging, control functions,…
Master Clock
Distribution
InIce