Sensitivity Studies
for KM3NeT
Rezo Shanidze, Sebastian Kuch
University of Erlangen
WP2 (
) Meeting
CPPM, Marseille, 24-25/10/2006
Introduction/Motivation
- What is the minimal flux of high energy cosmic neutrinos
which can be detected with KM3NeT detector ?
- What is the minimal flux which is necessary for 5s
discovery of neutrino point sources ?
- How KM3NeT sensitivity depends on detector
configuration (geometry, OM) and environmental (site)
parameters ?
- How the sensitivity depends on KM3NeT performance
parameters, for example energy and angular resolution ?
KM3NeT WP2 meeting
CPPM, Marseille, 25/10/2006
2
Current Limit (Diffuse nm Flux )
Current AMANDA limit
diffuse kn E-2 nm -flux,
( En> 100-300 TeV) ,
kn  ~ 10 -7 (GeV-1 cm-2s-1sr-1 )
with ~30% systematic uncertainty
IceCube (1 year):
5s:
10-8 E-2
90%c.l. : 4 10-9 E-2
Astropart.Phys. 20(2004), 507
astro-ph/0305196
T.Montaruli, asto-ph/0608140
KM3NeT WP2 meeting
CPPM, Marseille, 25/10/2006
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Current Limit ( Point Sources )
Flux model:
F(En)= kn E-2
Current AMANDA limit:
kn ~ 10 -7 ( GeV-1 cm-2 s-1 )
IceCube (1 year):
5s :
7 10-9 E-2
90% c.l.: 2 10-9 E-2
T.Montaruli, astro-ph/0608140
KM3NeT WP2 meeting
CPPM, Marseille, 25/10/2006
Astropart.Phys. 20(2004), 507
astro-ph/0305196
4
Sentivity and Event Rates
Events in n-experiment (KM3NET):
- Number of detected (observed) events – ND(E)
- Number of background (from MC) events – NB(E)
Sensitivity:
ND(E) ~ NB(E) g max.(Nmax) of cosmic n (NC):
Fn(En) upper limit (90% c.l.)
ND(E) > NB(E) g cosmic n events (NC) and significance (>3s):
Fn(En) cosmic n-flux
F(En) = kn E-G
‘Sensitivity: (k ) depends:
n
- energy threshold (E)
- power index (G)
Cosmic neutrino flux:
KM3NeT WP2 meeting
CPPM, Marseille, 25/10/2006
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Event Rates and Detector Models
Numbers of neutrino events:
N(E) = T ∫ F(En,Wn) A(En,Wn) dEn dWn
E
KM3NeT detector models/effective area:
talk by Sebastian Kuch
( asto-ph/0606507)
Different configurations:
- Homogeneous geometry
- Ring geometry
-Cluster geometry
with multPMT OMs.
Detector effects not considered:
Trigger and reconstruction efficiency,
Energy reconstruction and resolution
Direction reconstruction and angular resolution
KM3NeT WP2 meeting
CPPM, Marseille, 25/10/2006
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KM3NeT Detectors
Cube geometry
For each KM3NeT detector:
- Detector geometry
(OM grid)
- OM type
- number of OMs
- Effective area
Detector performance
vs. nm energy:
- Diffuse flux sensitivity
for knE-G flux, (G=1,5-2.5)
- WB events
contribution from :
B. Hussendörfer
KM3NeT WP2 meeting
CPPM, Marseille, 25/10/2006
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KM3NeT Detector Configurations
Ring geometry
KM3NeT WP2 meeting
Cluster geometry
CPPM, Marseille, 25/10/2006
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Upper Limit (Diffuse Flux)
Most simple case (Unfortunately most unrealistic !):
no background (atm- nm) events: NB(E) =0
kn(E) = Nmax / (2p T ∫ E-G A(En) dEn)
Upper limit (Nmax  m) from
Poisson statistics P(m,n)
Probability
P(m,0)=1-c.l. (Confidence Level)
For 90% c.l. g m=2.3
P(2.3,n)
Feldman and Cousins approach: m=2.44
(Phys. Rev. D57(1998) 3873, physics/9711021)
Events Observed (n)
KM3NeT WP2 meeting
CPPM, Marseille, 25/10/2006
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Upper Limits with Background
No cosmic neutrinos observed ND(E)=NB(E)
Number of background events NB(E) g calculated from atm-n flux (Volkova)
Nmax (90% c.l.)
Nmax (90% c.l.) obtained from
Feldman-Cousins approach:
TFeldmanCousins class
in ROOT.
Number of events (NB)
KM3NeT WP2 meeting
CPPM, Marseille, 25/10/2006
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kn (GeV-1cm-2 s-1sr-1)
Upper Limit (vs Emin )
Upper Limit for the E-2
neutrino diffuse flux
( no background case):
for different KM3NeT
models:
Atm-n
IceCube
1. Homogeneous
geometry
(Cuboid grid)
2. Ring geometry
E > Emin (GeV)
KM3NeT WP2 meeting
CPPM, Marseille, 25/10/2006
3. Cluster geometry
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kn (GeV-1cm-2 s-1sr-1)
Upper Limit (vs Emin )
Upper Limit for the E-2
neutrino diffuse flux
( no background case):
for different KM3NeT
models:
E-2.5
1. Homogeneous
geometry
(Cuboid grid)
E-2.0
E-1.5
for different G=
1, 1.5, 2, 2.5
E-1.0
E > Emin (GeV)
KM3NeT WP2 meeting
CPPM, Marseille, 25/10/2006
12
kn ( GeV-1 cm-2 s-1sr-1)
Upper Limit (vs G )
Upper limit (sensitivity)
of KM3NeT detector to
the diffuse knE-2 flux
of cosmic neutrinos vs. G
E> 100 TeV
The sensitivity calculated
with different Emin = 100 TeV.
KM3NeT model used in
Calculations:
Homogeneous cube
power index (G)
KM3NeT WP2 meeting
CPPM, Marseille, 25/10/2006
13
kn (GeV-1 cm-2 s-1sr-1)
Diffuse Flux Sensitivity
Upper Limit for the E-2
neutrino diffuse flux
above Emin > 100 TeV
Nmax obtained for
Feldman-Cousins
approach
Calculations for
homogeneous cube
E > Emin (GeV)
KM3NeT WP2 meeting
CPPM, Marseille, 25/10/2006
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kn (GeV -1 cm-2 s-1)
Sensitivity to Point Sources
Sensitivity for
kn E-G
point sources:
 DW(En) g
Emin > 1 TeV
E> 1 TeV
KM3NeT sensitivity
(90% c.l.) for point
sources vs. G ,
in the absence
of atm-n background
power Index (G)
KM3NeT WP2 meeting
CPPM, Marseille, 25/10/2006
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kn x 10 -12 ( TeV -1 cm-2 s-1)
Sensitivity to H.E.S.S. Sources
•
E> 1 TeV
KM3NeT sensitivity
(90% c.l.) for point
sources in the absence
of atm-n background.
and spectral parameters
of 26 H.E.S.S. sources
from
A.Kappes et al.,
astro-ph/0607286
(•) H.E.S.S. sources
power Index (G)
KM3NeT WP2 meeting
CPPM, Marseille, 25/10/2006
•
- visibility factor for the
source is included.
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Summary and Outlook
• Simple model for KM3NeT sensitivity considered
Very preliminary !
•
90% c.l. upper limits for diffuse neutrino flux estimated for
for different KM3NeT detectors in the simple cases.
- upper limit for point like sources compared to
potential neutrino fluxes from Galactic H.E.S.S. sources
•
Next steps:
- Sensitivity study for selected KM3NeT detectors,
with selected (benchmark) atm-n background flux.
- Comparison with other MC studies.
KM3NeT WP2 meeting
CPPM, Marseille, 25/10/2006
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