Transcript vandy_draft4 - IceCube - University of Wisconsin–Madison

Recent Results From
AMANDA and IceCube
Jessica Hodges
University of Wisconsin – Madison
for the IceCube Collaboration
Frontiers in Contemporary Physics: May 23, 2005
Why study neutrinos?
p


Protons: easily detected, but deflected by
magnetic fields. Direction of cosmic ray origin
is unknown.
Photons: absorbed by matter and will interact
with the microwave and IR backgrounds.
Carry directional information.
Neutrinos: not deflected by magnetic fields,
therefore they keep their directional
information. Low cross-section means they
rarely interact and are hard to detect.
AMANDA
IceCube
Neutrino Production
Cosmic accelerators that are suspected to produce high energy
cosmic rays include:
Gamma Ray Bursts (GRBs)
Active Galactic Nuclei (AGNs)
Supernova Remnants
?
Due to Fermi acceleration, neutrinos are
predicted to arrive with an E-2 energy spectrum
Bottom-Up scenario
p + (p or )   + X  e , + X
e :  :  = 1 : 2 : 0 at source
e :  :  = 1 : 1 : 1 at Earth (due to oscillations)
Where are we ?
South Pole
Dome
AMANDA
1500 m
Summer camp
Amundsen-Scott South Pole Station
2000 m
[not to scale]
IceCube Collaboration
Chiba University, Chiba, Japan
CTSPS, Clark Atlanta University, Atlanta, GA, USA
DESY, Zeuthen, Germany
Humboldt Universität, Berlin, Germany
Imperial College, London, UK
Institute for Advanced Study, Princeton, NJ, USA
Lawrence Berkeley National Laboratory, Berkeley, CA, USA
Pennsylvania State University, University Park, PA, USA
Amundsen-Scott Station, Antarctica
Southern University and A & M College, Baton Rouge, LA, USA
Stockholm Universitet, Stockholm, Sweden
Universität Dortmund, Dortmund, Germany
Universität Mainz, Mainz, Germany
Universität Wuppertal, Wuppertal, Germany
Université Libre, Brussels, Belgium
Université de Mons-Hainaut, Mons, Belgium
University Gent, Gent, Belgium
University of Alabama, Tuscaloosa, AL
University of California-Berkeley, Berkeley, CA, USA
University of California-Irvine, Irvine, CA, USA
University of Canterbury, Christchurch, New Zealand
University of Delaware, Newark, DE, USA
University of Kansas, Lawrence, KS, USA
University of Maryland, College Park, MD, USA
University of Oxford, Oxford, UK
University of Wisconsin-Madison, Madison, WI, USA
University of Wisconsin-River Falls, River Falls, WI, USA
Uppsala Universitet, Uppsala, Sweden
Utrecht University, Utrecht, Netherlands
Vrije Universiteit Brussel, Brussels, Belgium
Antarctic Muon and Neutrino Detector Array
Ice Properties:
dust layers exist at different depths
AMANDA-B10
for wavelength = 400 nm,
average absorption length = 110 m
average effective scattering length = 20 m
inner 10 strings
302 Optical Modules
Operating from 1997-1999
AMANDA-II
19 strings
677 Optical Modules
Operating from 2000-now
Trigger Rate ~80 Hz
PMT noise
~ 1kHz
Optical Module:
Down-looking
photomultiplier tube
enclosed in a pressure
resistant glass
sphere
Neutrino Induced Events in the Ice
νμ charged current interactions produce
Cherenkov light along long tracks.
“Up-going”
“Down-going”
(from Northern sky)
(from Southern sky)
Pointing resolution ~ 2 o
Energy resolution ~ 0.3 - 0.4 in log10(E / TeV)
Coverage: 2
Muon Track
Cascade
~15 m
νe and ντ charged current interactions
and all flavor neutral current interactions
induce cascades in the ice.
Pointing resolution ~ 30o
Energy resolution ~ 0.1 – 0.2 in log10 (E / TeV)
Coverage: 4
Diffuse Neutrino Analysis (TeV – PeV)
downgoing muons and neutrinos


E-2
Arbitrary units
Diffuse flux = flux from
unresolved neutrino sources
E-3.7
Number of Optical Modules hit (scales with the neutrino energy)
“Signal”


Separate atmospheric and E-2 signal
neutrinos with an energy cut.
Reconstructed Muon
Event:
To select high quality upgoing
events, apply cuts to the data
based on the observables of the
event.
Monte Carlo based sensitivity optimization
using the Feldman – Cousins prescription
Another Method of Setting a Diffuse νμ Limit
Reconstruct the atmospheric
neutrino spectrum and use
this to set a diffuse limit
* Preliminary *
Neural Network Energy
Reconstruction
Regularized unfolding gives the
energy spectrum
Setting a limit on the diffuse
flux of E-2 cosmic neutrinos:
log of the neutrino energy (GeV)
This limit corresponds to the highest
allowed E-2 cosmic neutrino signal
within the the uncertainty of the
highest energy bin.
Limit on Diffuse E-2 νμ flux: E2 (E) < 2.6 x 10-7 GeV cm-2s-1sr-1
Range: 100 – 300 TeV
Data Year: 2000
Muon Neutrino Flux Limits
Preliminary
Preliminary
Cascade Diffuse Neutrino Analysis
Sensitive to all three neutrino flavors
Cuts optimized on
topology and energy
Nobs = 1 event
+0.69
Natm  = 0.90
Natm ν = 0.06
-0.43
+0.09
-0.04
± 25%norm
All flavor limit on diffuse E-2 neutrino flux: E2 (E) < 8.6 x 10-7 GeV cm-2s-1sr-1
Range: 50 TeV – 5 PeV
Astroparticle Physics 22 (2004) 127
Data Year: 2000
PeV – EeV Diffuse Neutrino Analysis
Ultra high energy neutrinos have large
cross-sections
--> PeV and EeV neutrinos that enter the
earth in the Northern Hemisphere are likely
to interact before reaching AMANDA
Best detection strategy: Look near the horizon and just above it.
True cosmic neutrino events should be very bright (large number of
hits in the detector).
Using a neural net trained to distinguish ultra high
energy cosmic E-2 events from background:
Limit on Diffuse E-2 neutrino flux: all E2 (E) < 0.99 x 10-6 GeV cm-2s-1sr-1
Range: 1 PeV – 3 EeV
Data Year: 1997
Neutrino Point Source Search
2000 – 2003 Sky Map
807 days of livetime
3329 upgoing events
(3438 atmospheric events expected)
All events shown are consistent with the
atmospheric neutrino background. No
extraterrestrial E-2 signal observed.
Two Search Methods:
1) Look for clusters of events around a predefined list of neutrino source candidates.
2) Grid search : Shift the grid repeatedly to look for a clustering of events. This allows
you to find sources not on the predefined list.
Neutrinos from Gamma Ray Bursts
10 min
-1 hour
+1 hour
Blinded
Window
Background determined on-source / off-time
Background determined on-source / off-time
Time of GRB (start of T90)
Using space and time coincidence leads to a very low background.
Year
Detector
Bursts
1997-2000
B-10 / A-II
312
Background
Predicted
Number
Observed
Event Upper
Limit
1.29
0
1.45
1.25
0
1.47
(BATSE)
2000-2003
* Preliminary *
A-II
139
(BATSE + IPN)
97-00 Flux Limit at Earth*: E2Φν≤ 4·10-8 GeV cm-2 s-1 sr-1
00-03 Flux Limit at Earth*: E2Φν≤ 3·10-8 GeV cm-2 s-1 sr-1
Separate analyses are currently underway using both the average Waxman-Bahcall
parameters and burst-specific observables.
Indirect Dark Matter Search for Neutralinos
Gravitationally Trapped in the Sun
Limits on muon
flux from the Sun
COLOR CODE:
Disfavored by CDMS II
Will be ruled out when
experiments reach 10x
current sensitivity
Require greater than 10x
current sensitivity to probe
SuperNova Early Warning System
SNEWS is a collaborative effort between
Super-K, SNO, LVD, KamLAND,
AMANDA, BooNE and several
gravitational wave experiments
AMANDA-II
AMANDA-B10
Bursts of low-energy (MeV) neutrinos
from core collapse supernovae
AMANDA detection:
- simultaneous increase of all PMT
count rates (~10 s)
- can detect 90% of SN within 9.4 kpc
- less than 15 fakes per year
IceCube
30 kpc
AMANDA-B10 sees 70% of the galaxy
AMANDA-II sees 90% of the galaxy
IceCube will see out to the LMC
IceCube: The Future
one cubic kilometer
300 m
80 strings with 60 Digital
Optical Modules per string
1450 m
AMANDA
2450 m
Optimized for detection of
TeV – PeV neutrinos
17 m vertical spacing of DOMs
125 m between strings
2 IceTop Tanks with 2 Digital
Optical Modules above each
IceCube string
Estimated completion: 2010
Event Simulation in IceCube
Very high energy events that saturate AMANDA will be clearly
distinguished in IceCube.
E = 375 TeV
E = 10 TeV
e cascade event
 muon event
~300m for
10 PeV 

double bang event
Recent Deployment
January 27, 2005
First IceCube String Deployed!
60 Digital Optical Modules are in the ice
8 IceTop tanks deployed
IceCube Drill Camp
IceTop
Conclusions
Limits have been set and multi-year AMANDA analyses
are getting closer to the Waxman-Bahcall diffuse neutrino
upper limit. However, no extraterrestrial neutrino signal has
been observed yet.
AMANDA is successful as a proof-of-concept and is the
largest neutrino detector in the world. IceCube is under
construction.
One IceCube string has been deployed and all DOMs are
communicating successfully.
Spring 2005 data event:
Run 872 Event 5945
First IceCube string
www.icecube.wisc.edu
[email protected]