Transcript Rezo Shanidze, Sebastian Kuch

MC studies of the KM3NeT
physics performance
Rezo Shanidze
VLVnT08 - Toulon, Var, France
22-24 April 2008
High energy neutrinos in KM3NeT
KM3NeT Neutrino Telescope:
“Optimal detection” of the high
energy ( above ~ 100 GeV)
cosmic neutrinos from:
- Dark matter annihilation
- Point sources
(AGN, SNR, … )
- Diffuse flux
( AGN n-flux, GZK-n, ... )
. . .
+
The “Grand unified” neutrino spectrum
from ASPERA Roadmap (phase I).
www.aspera-eu.org
R. Shanidze, VLVTnT08 - Toulon, Var, France, 22-24 April, 2008
Exotic particles like magnetic
monopoles and nuclearites.
MC optimization studies in Erlangen
S.Kuch, PhD thesis:
Design studies for the KM3NeT Neutrino Telescope
www.slac.stanford.edu/spires/find/hep/www?r=FAU-PI1-DISS-07-001
MC simulations of different detector configurations and comparison of
benchmark parameters: Neutrino effective area Aeff(En)
Angular resolution of reconstructed m: DQ(m)
Different detector components and geometry configurations
were studied in ECAP:
PMT
• Photo-multipliers (PMT)
...
OM
PMT
• Optical modules (OM)
...
Storey
OM
Storey
• Storey on detection
Detection unit
...
unit (string)
Detection unit
Storey
Geometry
...
configuration
Detection unit
R. Shanidze, VLVTnT08 - Toulon, Var, France, 22-24 April, 2008
Storey / OM / PMT in MC studies
KM3NeT storey types studied in Erlangen:
- Storey with large PMT/OM (used in AMANDA/IceCube, ANTARES)
- Multi-PMT OM (“Flykt-OM”) with 3” PMTs ( Photonis XP53X2 )
with large PMT
a) OM with one 10” PMT
b) Two OMs with 10”PMT
c) ANTARES type with 3 OMs
d) ANTARES type with 6 OMs
with Multi-PMT OM
e) storey with 3 cylindrical OMs
f) spherical storey with
36 or 42 PMTs
g) spherical storey with 21 PMTs.
KM3NeT parameters fixed ( ~ 5% ) in MC:
3
a) instrumented volume ( 1 km ) b) total photo-cathode area
R. Shanidze, VLVTnT08 - Toulon, Var, France, 22-24 April, 2008
KM3NeT geometry configurations
Basic geometry configurations: homogeneous (a), cluster (b), ring (c)
( Alternative configurations, for example IceCube type (d), . . . ) .
a
c
b
d
R. Shanidze, VLVTnT08 - Toulon, Var, France, 22-24 April, 2008
For each basic
configuration the
several models
with the different
parameters
were simulated..
For example,
with the different
numbers for:
- detection units,
(strings / lines)
- storey / line
- OM / Storey
...
MC simulations and benchmark parameters
Modified ANTARES Software was used for MC simulations.
9
For each KM3NeT configuration: 2 x 10 nm + A g m + X
(nm CC events).
Neutrino effective area AEff(En) defines the neutrino event
rates for the given neutrino flux F(En) (cosmic neutrino flux: ~ E -2 )
dN/dt = ∫ F(En) AEff(En) dEn
n (En )    NA  Vm  em  PEarth
n
 , NA
Vm
em
PEarth
Neutrino/nucleon cross-section
Density ( sea water), Avogadro number
Volume for simulation of nmN CC interactions
Detection efficiency ( ratio of detected and simulated events)
Absorption in Earth
Angular resolution DQm defines the search-window for the neutrino point sources.
For the given flux from the point source the detection significance ~ 1/ DQm .
R. Shanidze, VLVTnT08 - Toulon, Var, France, 22-24 April, 2008
Comparison of Different Options
Homogenous vs. cluster configuration
Low energy region
En < 1 TeV
Physics goal:
Dark matter from
the sun, GC
Neutrino angular
resolution is defined
by angle between
neutrino and muon.
DQnm
R. Shanidze, VLVTnT08 - Toulon, Var, France, 22-24 April, 2008
Comparison of Different Options
Homogenous vs. ring configuration
Ring configurations
i
maximal detector
surface area
with dense
instrumentation inside
ring.
For high energy
region ( > 10 TeV):
slightly worse than
homogenous
configuration
R. Shanidze, VLVTnT08 - Toulon, Var, France, 22-24 April, 2008
KM3NeT “reference detector” for sensitivity studies
Reference detector:
15 x 15 det. units
( Ld=95 m)
37 storey (8325)
(Ls = 16.5 m )
1 Multi-PMT OM
21x 3’’ PMT
Instrumented
volume
1.05 km3
R. Shanidze, VLVTnT08 - Toulon, Var, France, 22-24 April, 2008
Calculation of the flux limit
For the neutrino flux:
The normalization factor (kn) is obtained from a number of events (Ns) for
a given flux model and neutrino detector effective area :
The flux limit (
The ratio
) can be obtained as:
is often called Model Rejection Factor (MRF)..
is calculated from Feldman-Cousins approach, where an upper limit of
signal events can be obtained with a given confidence level ( 90% CL), for
a case when number of detected events is compatible to the bkg. expectations.
R. Shanidze, VLVTnT08 - Toulon, Var, France, 22-24 April, 2008
Atmospheric neutrinos
Zenith angle averaged atmospheric
neutrino flux obtained by different groups
together with theoretical expectations from
Waxman-Bahcall (WB) calculations
R. Shanidze, VLVTnT08 - Toulon, Var, France, 22-24 April, 2008
Integrated event rates as a function
n- energy (lower limit of integration)
for the cosmic n-diffuse WB flux and
Atm-n flux (Bartol model).
Neutrino flux limit from the point sources
Expected flux vs.
source declination
for the KM3NeT
reference detector.
Experimental results
from AMANDA and
MACRO are plotted
together with the
expected limits from the
ANTARES and IceCube
neutrino telescopes.
R. Shanidze, VLVTnT08 - Toulon, Var, France, 22-24 April, 2008
Neutrino diffuse flux limit
Expected diffuse flux limit
calculated from nm events.
The experimental upper
limit for AMANDA and
expected limits for the
ANTARES and IceCube
detectors are plotted
together with the atm-n
flux and the theoretical
expectation according to
WB calculations
R. Shanidze, VLVTnT08 - Toulon, Var, France, 22-24 April, 2008
Summary
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The different configurations of the KM3NeT neutrino telescope were
simulated and studied with the modified ANTARES software.
None of the studied KM3NeT configurations is superior over the full
energy range. Therefore it is crucial to define the physics priorities of
the KM3NeT neutrino telescope.
KM3NeT will set neutrino flux limits from the cosmic point sources
which are about 50 times smaller than the expected flux limits from the
current ANTARES telescope. The sources with a neutrino flux above
obtained limits will be detected KM3NeT with the different level of
significance, according to the source flux.
The cosmic neutrino diffuse flux limit obtained with KM3NeT will be
well below of the expected theoretical limits (for example WaxmanBahcall bound).
R. Shanidze, VLVTnT08 - Toulon, Var, France, 22-24 April, 2008