Download Results from the AMANDA Neutrino Telescope

Results from the AMANDA
Neutrino Telescope
CRIS06, Catania, June 2006
Juande D. Zornoza
University of Madison-Wisconsin
Neutrino Astronomy
High energy astronomy: Which probes can we use?
Neutrino CV
•Neutral
•Stable
•Weakly interacting*
Photon and proton mean free range path
*very large
detectors needed
• Photons interact with the
CMB and with matter
• Cosmic rays are deflected
by magnetic fields and also
interact with matter
• Neutrons are not stable
What else? Oh, yeah, neutrinos!
Production Mechanisms

Gamma and cosmic ray astrophysics
are deeply related with neutrino
astronomy:
N  X    ( K  ...)  Y      (  )  Y
Cosmic rays

e  e ( e )   (  )
N  X  0 Y    Y
Gamma ray astronomy
Neutrino flavor rate:
e:: ~ 1:2:<10-5 at the source
e:: ~ 1:1:1 at the detector
Scientific Scopes
?
Energy
Physics
Signature
~MeV
Supernovae
Average
increase in
the PMT
counting rate
GeV-TeV
TeV-PeV
PeV-EeV
EeV
Neutralino
search
Astrophysical
sources
(AGNs,
GRBs, MQs)
AGNs, TD,
GZK
neutrinos
?
Almost
horizontal
tracks
Down-going
tracks
Up-going
muons
Up-going
muons and
cascades
Other physics: monopoles, Lorentz invariance, super-massive DM , SUSY Q-balls, etc...
AMANDA/IceCube Collaboration
• Bartol Research Institute, Delaware, USA
• Pennsylvania State University, USA
• UC Berkeley, USA
• UC Irvine, USA
•Clark-Atlanta University, USA
• Univ. of Maryland, USA
USA (12)
• IAS, Princeton, USA
• University of Wisconsin-Madison, USA
• University of Wisconsin-River Falls, USA
• LBNL, Berkeley, USA
• University of Kansas, USA
• Southern University and A&M College, Baton Rouge, USA
Japan
Europe (13)
• Chiba university, Japan
• University of Canterbury, Christchurch, NZ
New Zealand
• Universite Libre de Bruxelles, Belgium
• Vrije Universiteit Brussel, Belgium
• Université de Gent, Belgium
• Université de Mons-Hainaut, Belgium
• Universität Mainz, Germany
• DESY-Zeuthen, Germany
• Universität Dortmund, Germany
• Universität Wuppertal, Germany
• Uppsala university, Sweden
• Stockholm university, Sweden
• Imperial College, London, UK
• Oxford university, UK
• Utrecht,university, Netherlands
Amundsen-Scott South Pole Station
Runway
South Pole
AMANDA-II
AMANDA Detector

1997-99: AMANDA-B10 (inner lines of AMANDA-II)



10 strings
302 PMTs
from 2000: AMANDA-II



19 strings
677 OMs
20-40 PMTs / string
SPASE
At the surface: SPASE
 Coincident events
 Angular resolution
 Cosmic ray
composition
1 km
2 km
trigger rate = 80 Hz
Signatures
CC- interactions:
long (~km) tracks
NC- and CC-e/ interactions:
cascades
15 m
  0.7  ( E / TeV )0.7
(tracks short w.r.t. the interOM distance)
• Other signatures, like double bang, are expected to be more rare.
Background
•There are two kinds of background:
p    ( K  ...)     
-Muons produced by cosmic rays in the
atmosphere (→ detector deep in the ice
and selection of up-going events).
-Atmospheric neutrinos (cut in the energy,
angular bin…).
n    ( K  ...)     
 e     e
p



p
 e     e


Ice Properties

Shorter scattering length than in sea, but longer
absorption length (larger effective volume):
Average optical ice parameters:
labs ~ 110 m @ 400 nm
lsca ~ 20 m @ 400 nm
Absorption
Scattering
ice
bubbles
dust
dust
Moreover, very “silent”
medium: dark noise < 1.5 kHz
Event reconstruction



The position, time and amplitude registered by
the PMTs allows the reconstruction of the track,
using Likelihood optimization techniques.
The angular resolution depends on the quality
cuts of each specific analysis. For instance, in the
point-like source search, it is 2.25-3.75 deg
(declination dependent).
Once reconstructed the positions of the tracks, we
can compare the number of events in each signal
bin with the background at that declination.
signal bin
background estimation
example of AMANDA event
Sky map
2000-2003 (807 days)
3329 s detected from Northern
Hemisphere
3438 atmospheric s expected
~92%
The largest fluctuation
(3.4) is compatible with
atmospheric background
Performance
Sensitivity to E-2 Point-like sources
average flux upper limit [cm-2s-1]
Neutrino Effective Area
AMANDA-B10
AMANDA-II
Ndet=Aeff × Time × Flux
sin(d)
•For E<10 PeV, Aeff grows with energy due to
the increase of the interaction cross section and
the muon range.
•For E>10 PeV the Earth becomes opaque to
neutrinos.
• Sensitivity: Average upper limit,
integrated above 10 GeV.
• Steady increase with time.
AGNs: Stacking source analysis
 Neutrino astronomy could be the
key for establishing the
hadronic/leptonic origin of the HE
photons from AGNs.
 Stacking-source analysis: The flux
from AGNs of the same type integrated
to enhance the statistics.
single source
sensitivity
(four years)
 No significant excess has been found.
The stacking approach improves the one
source limit by a factor three, typically.
Multi-wavelength approach


Transient events also provide an opportunity to enhance sensitivity
We can look for correlations with active periods from electromagnetic
observations:


Blazars: X-rays
Microquasars: radio
Period wtih
high activity
#events in high
state
Expected
background
in high state
Markarian 421
141 days
0
1.63
1ES1959+650
283 days
2
1.59
Cygnus X-3
114 days
2
1.37
Source
sources: TeV blazars, microquasars and variable sources from EGRET
2000-03 data
Transient sources


When the variable character of the source is evident, but the EM
observations are limited, we can use the sliding-window technique.
For the time-rolling source search, events in a sliding time window are
searched:

#events
(4 years)
Expected background
(4 years)
Period duration
Extragalactic
Markarian 421
6
5.58
40 d
1ES1959+650
5
3.71
40 d
3EG J1227+4302
6
4.37
40 d
QSO 0235+164
6
5.04
40 d
Galactic

Galactic: 20 days
Extragalactic: 40 days
Source
Cygnus X-3
6
5.04
20 d
GRS 1915+105
6
4.76
20 d
GRO J0422+32
5
5.12
20 d
sources: TeV blazars, microquasars and variable sources from EGRET
Orphan Flare


Three events in 66 days within the
period of a mayor 1ES 1959+650
burst (orphan flare:s but no X-rays)
A posteriori search  undefined
probability of random coincidence.
sliding search window
Diffuse fluxes
 Atmospheric
neutrino spectrum is reconstructed
using regularization-unfolding techniques.
 No extraterrestrial diffuse component has been
observed.
E2 d/dE = 1.1 x 10-7 GeV cm-2 s-1 sr-1
(over the range 16 TeV to 2 PeV)
UHE neutrinos (I)




UHE neutrinos (>106 GeV) can
be produced in several
scenarios (AGNs, topological
defects, GZK…)
>107 GeV the Earth is opaque
to neutrinos  search for
horizontal tracks.
Background: muon bundles
from atmospheric showers.
Neural network trained to
distinguish between signal and
background
simulated UHE event
UHE neutrinos (II)

Signal versus background:





Signal produces higher light density
There are more hits in UHE single muons, due to the
after-pulsing in the photomultipliers.
Background events are produced mainly vertically downwards and signal events are expected to be horizontal.
Different residual time distributions (because of afterpulsing)
Center of gravity of hits pulled away from the geometrical
center of the detector for down-going bundles.
UHE neutrinos (III)

2000 data used for this analysis:



20% for the optimization of cuts
80% after unblinding is approved
There is a factor two of improvement in the sensitivity w.r.t. AMANDA B10
Limit = 3.710-7 GeV cm-2 s-1 sr-1
(from 1.8105 to 1.8109 GeV)
UHE neutrinos (IV)

PRELIMINARY sensitivities to different models of UHE production:
Number expected
in 80% of 1 year
(138.8 days)
all 
MRF for 80% sample
(FC = 3.49)
AGN core (Stecker et al 96)
37.0
0.09
AGN core (Stecker et al 92)
8.9
0.39
AGN jet (Protheroe 96)
8.9
0.40
AGN jet (Halzen and Zas 97)
8.5
0.41
Z-Burst (Kalashev et al 02)
3.6
0.96
Mono-Energetic p-γ (Semikoz 03)
0.65
5.4
Topological Defect (Sigl et al 98)
0.63
5.5
E-2 p-γ (Semikoz 03)
0.45
7.8
Z-Burst (Yoshida et al 98)
0.15
24.0
p-γ (Engel et al 01)
0.012
298.8
Source
L. Gerhardt
SGR 1806-20
The SGR 1806-20 flare (Dec. 2004) was more than one
order of magnitude more powerful (2x1046 erg) than
previous flares: detectors saturated.
RA (J2000) 18h 08m 39.4s = 272.16 deg
DEC (J2000) -20deg24'39.7" = -20.41 deg
Duration < 0.6 s
Satellite
0.4 s
+
Trigger time at Earth
(ms)
GEOTAIL
21:30:26.71
INTEGRAL
21:30:26.88
RHESSI
21:30:26.64
CLUSTER 4
21:30:26.15
Double Star
21:30:26.49
Time window 1.5 s
Swift-BAT light curve
We try to observe down-going muons produced by TeV photons
discriminating the background of atmospheric muons using an angular
and a time window
SGR 1806-20
5 events,
time window: 1.5 s
Confidence interval=5
Statistical Power=90%


Discovery

Optimum cone size: 5.8°

Best MDF: 2.3

Observed events needed: 4

Background: 0.06
MDF have jumps when we have to increase the (discrete) number of events needed to
satisfy the condition of 5 confidence interval.
MRF behaves smoothly since only the mean expected background in taken into account.
SGR 1806-20

Unfortunately, no event was found after unblinding, so upper
limits have been calculated.
Effective areas
neutrinos
gammas
• Limits in the constant of a d/dE=A
E-1.47 flux are set, constraining both
the HE gamma and neutrino emission.
Limit in flux normalization
GRBs (average spectrum)



Search time window: from 10 sec
before the burst start to the end of
the burst.
Precursor: from -110 sec to -10 sec.
Background estimation: from 1
hour before to 1 hour after (except
10 minutes around the burst which
remain unblinded)
years
# GRBs
97-00
312
00-03
139
00-03 (with precursor)
50
00
74
selection criterion limit (GeV cm-2 sr-1)
BATSE
BATSE + IPN
BATSE
410-8
310-8
510-8
9.510-7
Neutralino Search




WIMPs would scatter elastically in
the Sun or Earth and become
gravitationally trapped.
They would annihilate producing
standard model particles.
Among the annihilation products,
only neutrinos can reach us.
Neutralinos annihilate in pair-wise
mode:
  l l  , W W  , Z 0 Z 0 , H10,2 H30 , Z 0 H10,2 , W  H 
and neutrinos are produced as
secondaries.

ann 
 annv 2
m2
ann: annihilation rate per unit of volume
ann: neutralino-neutralino cross-section
v: relative speed of the annihilating particles
: neutralino mass density
m: neutralino mass
Neutralino Search
excluded
by Edelweiss
The Sun is the most promising source of neutralinos.
Neutralino density in the Earth is diminished the effect of the Sun mass.
Conclusions




AMANDA has been operating for almost one
decade.
No extraterrestrial neutrino has been observed
above the atmospheric background, YET…
Increasingly stringent limits have been set in
but sometimes
point-like sources, diffuse fluxes, neutralinos…
success comes
A bigger detector is needed  IceCube
after much work
and patience!
(already in construction!)
Thanks to the organizers!
Backup transparencies
Particle Physics
Monopoles


Monopoles would also give a large signal in the detector, which can be
discriminated from high energy muons.
Two signatures are possible:
Direct
emission (βm>0.74): ×8500 wrt muon
Induced δ-ray emission (βm>0.51)
GRB model parameterization
s
b


A ' a  b  1

b
a
b2
b  a  1
   ( E 0 , z )
b
b
   (F , t90 , z )
s
A  F
s
GRBs (individual spectrum)


The individual spectrum can be
used instead of the average to
enhance the sensitivity for a
given burst.
The parameters of the Band
function of the GRB030329
burst were calculated.
Model
neutrino energy flux (GeV cm-2 s-1)
1
2
3
Sensitivity
Limit
(GeV s-1 cm-2)
(GeV s-1 cm-2)
isotropic (1)
0.157
0.150
beamed (2)
0.041
0.039
average (WB) (3)
0.036
0.035
GRBs: individual bursts
AGN models


Low energy (from radio up to UV / Xray): non-coherent synchrotron radiation.
High energy (up to TeV) under debate:
leptonic versus hadronic models.