Rezo Shanidze

Rezo Shanidze

MC studies of the KM3NeT physics performance

VLVnT08 - Toulon, Var, France 22-24 April 2008

R. Shanidze, VLVTnT08 - Toulon, Var, France, 22-24 April, 2008

High energy neutrinos in KM3NeT

The “Grand unified” neutrino spectrum from ASPERA Roadmap (phase I). www.aspera-eu.org

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 -flux, GZK-, ...)

. . . +Exotic particles like magneticmonopoles and nuclearites.


MC optimization studies in Erlangen

Detection unitDetection unit. . . Detection unit

Geometry configuration

MC simulations of different detector configurations and comparison of benchmark parameters: Neutrino effective area Aeff(E) Angular resolution of reconstructed : ()

PMT . . . PMT Storey

Storey . . . Storey

Different detector components and geometry configurations were studied in ECAP:

OM . . . OM

• Photo-multipliers (PMT) • Optical modules (OM)

• Storey on detection

unit (string)

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


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: a) instrumented volume ( 1 km3) b) total photo-cathode area


KM3NeT geometry configurations

Basic geometry configurations: homogeneous (a), cluster (b), ring (c) ( Alternative configurations, for example IceCube type (d), . . . ) .

a b

c d

For each basic configuration theseveral modelswith the differentparameterswere simulated..

For example, with the differentnumbers for: detection units, (strings / lines)storey / line OM / Storey . . .


MC simulations and benchmark parameters

Neutrino effective area AEff(E) defines the neutrino event

rates for the given neutrino flux (E) (cosmic neutrino flux: ~ E -2 )

dN/dt = ∫ (E) AEff(E) dE

Angular resolution defines the search-window for the neutrino point sources. For the given flux from the point source the detection significance ~ 1/ .

(E) NA V PEarth

Neutrino/nucleon cross-section , NA Density ( sea water), Avogadro number V Volume for simulation of N CC interactions Detection efficiency ( ratio of detected and simulated events) PEarth Absorption in Earth

Modified ANTARES Software was used for MC simulations.

For each KM3NeT configuration: 2 x 109 A + X ( CC events).


Comparison of Different Options Homogenous vs. cluster configuration

Low energy region E < 1 TeV

Physics goal: Dark matter from the sun, GC

Neutrino angular resolution is defined by angle between neutrino and muon.


Comparison of Different Options

Ring configurations maximal detector surface area with dense instrumentation inside ring.

For high energy region ( > 10 TeV): slightly worse than homogenous configuration

Homogenous vs. ring configuration


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


Calculation of the flux limit

For the neutrino flux:

The normalization factor (k) is obtained from a number of events (Ns) for a given flux model and neutrino detector effective area :

The flux limit ( ) can be obtained as:

The ratio 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.


Atmospheric neutrinos

Zenith angle averaged atmospheric neutrino flux obtained by different groups together with theoretical expectations from Waxman-Bahcall (WB) calculations

Integrated event rates as a function- energy (lower limit of integration)for the cosmic -diffuse WB flux andAtm- 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.


Neutrino diffuse flux limit

Expected diffuse flux limit calculated from events.

The experimental upper limit for AMANDA and expected limits for theANTARES and IceCube detectors are plotted together with the atm- flux and the theoretical expectation according to WB calculations


Summary • 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 Waxman- Bahcall bound).

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Rezo Shanidze