Frontiers in Contemporary Physics: May 23, 2005 Recent Results From AMANDA and IceCube Jessica...
-
Upload
ralph-mcgee -
Category
Documents
-
view
214 -
download
0
Transcript of Frontiers in Contemporary Physics: May 23, 2005 Recent Results From AMANDA and IceCube Jessica...
Frontiers in Contemporary Physics: May 23, 2005
Recent Results From AMANDA and IceCube
Jessica HodgesUniversity of Wisconsin – Madison
for the IceCube Collaboration
Why study neutrinos?
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.
p
AMANDA
IceCube
Neutrino ProductionCosmic 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 scenariop + (p or ) + X e , + X
e : : = 1 : 2 : 0 at source
e : : = 1 : 1 : 1 at Earth (due to oscillations)
Amundsen-Scott South Pole Station
South PoleDome
Summer camp
AMANDA
road to work
1500 m
2000 m
[not to scale]
Where are we ?
Université de Mons-Hainaut, Mons, BelgiumUniversity Gent, Gent, BelgiumUniversity of Alabama, Tuscaloosa, ALUniversity of California-Berkeley, Berkeley, CA, USAUniversity of California-Irvine, Irvine, CA, USAUniversity of Canterbury, Christchurch, New ZealandUniversity of Delaware, Newark, DE, USAUniversity of Kansas, Lawrence, KS, USAUniversity of Maryland, College Park, MD, USAUniversity of Oxford, Oxford, UKUniversity of Wisconsin-Madison, Madison, WI, USAUniversity of Wisconsin-River Falls, River Falls, WI, USAUppsala Universitet, Uppsala, SwedenUtrecht University, Utrecht, NetherlandsVrije Universiteit Brussel, Brussels, Belgium
Chiba University, Chiba, JapanCTSPS, Clark Atlanta University, Atlanta, GA, USA
DESY, Zeuthen, GermanyHumboldt Universität, Berlin, Germany
Imperial College, London, UKInstitute for Advanced Study, Princeton, NJ, USA
Lawrence Berkeley National Laboratory, Berkeley, CA, USAPennsylvania State University, University Park, PA, USA
Amundsen-Scott Station, AntarcticaSouthern University and A & M College, Baton Rouge, LA, USA
Stockholm Universitet, Stockholm, SwedenUniversität Dortmund, Dortmund, Germany
Universität Mainz, Mainz, GermanyUniversität Wuppertal, Wuppertal, Germany
Université Libre, Brussels, Belgium
IceCube Collaboration
Antarctic Muon and Neutrino Detector Array
AMANDA-B10inner 10 strings302 Optical ModulesOperating from 1997-1999
AMANDA-II19 strings677 Optical ModulesOperating from 2000-now
Trigger Rate ~80 HzPMT noise ~ 1kHz
Optical Module:Down-looking photomultiplier tube enclosed in a pressure
resistant glass sphere
Ice Properties: dust layers exist at different depths
for wavelength = 400 nm,average absorption length = 110 maverage effective scattering length = 20 m
Neutrino Induced Events in the Ice
“Up-going”(from Northern sky)
“Down-going”(from Southern sky)
νμ charged current interactions produce
Cherenkov light along long tracks.Pointing resolution ~ 2 o
Energy resolution ~ 0.3 - 0.4 in log10
(E / TeV)Coverage: 2
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
Muon Track
Cascade~15 m
Diffuse Neutrino Analysis (TeV – PeV)
“Signal”
downgoing muons and neutrinos
E-3.7E-2
Number of Optical Modules hit (scales with the neutrino energy)
Reconstructed Muon Event:
To select high quality upgoing events, apply cuts to the data based on the observables of the event.
Separate atmospheric and E-2 signal neutrinos with an energy cut. Monte Carlo based sensitivity optimization using the Feldman – Cousins prescription
Diffuse flux = flux from unresolved neutrino sources
Arb
itra
ry u
nit
s
Another Method of Setting a Diffuse νμ Limit
log of the neutrino energy (GeV)
Reconstruct the atmospheric neutrino spectrum and use this to set a diffuse limit
Neural Network Energy Reconstruction
Regularized unfolding gives the energy spectrum
Setting a limit on the diffuse flux of E-2 cosmic neutrinos: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
* Preliminary *
Preliminary
Preliminary
Muon Neutrino Flux Limits
Cascade Diffuse Neutrino Analysis
Nobs = 1 event
Natm = 0.90
Natm ν = 0.06 ± 25%norm
Astroparticle Physics 22 (2004) 127
Sensitive to all three neutrino flavors
+0.69
-0.43
+0.09
-0.04
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 Data Year: 2000
Cuts optimized on topology and energy
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 E
2 (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 Map807 days of livetime3329 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
Background determined on-source / off-time Background determined on-source / off-time
Blinded Window
-1 hour +1 hour10 min
Time of GRB (start of T90
)
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
Using space and time coincidence leads to a very low background.
Separate analyses are currently underway using both the average Waxman-Bahcall parameters and burst-specific observables.
Year Detector Bursts Background Predicted
Number Observed
Event Upper Limit
1997-2000 B-10 / A-II 312 (BATSE)
1.29 0 1.45
2000-2003 A-II 139(BATSE + IPN)
1.25 0 1.47* Preliminary *
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
detection
radius
SuperNova Early Warning System
SNEWS is a collaborative effort between Super-K, SNO, LVD, KamLAND, AMANDA, BooNE and several gravitational wave experiments
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
AMANDA-II
AMANDA-B10
IceCube30 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
80 strings with 60 Digital Optical Modules per string
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
1450 m
2450 m
300
m
AMANDA
~300m for 10 PeV
Event Simulation in IceCube
Very high energy events that saturate AMANDA will be clearly distinguished in IceCube.
muon event
e cascade event
double bang event
E = 10 TeV
E = 375 TeV
Recent Deployment
January 27, 2005First IceCube String Deployed!60 Digital Optical Modules are in the ice
8 IceTop tanks deployed
IceCube Drill Camp
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.
www.icecube.wisc.edu
ConclusionsIceTop
Spring 2005 data event:
Run 872 Event 5945
First IceCube string