XXIII International Conference on Neutrino Physics and Astrophysics 2008

Christchurch, New Zealand

Contacts: christopher.naumann@cea.fr gilles.maurin@cea.fr

Detector Design Studies for a Cubic Kilometre Detector Design Studies for a Cubic Kilometre Deep Sea Neutrino Telescope – KM3NeTDeep Sea Neutrino Telescope – KM3NeT

Detector Design Studies for a Cubic Kilometre Detector Design Studies for a Cubic Kilometre Deep Sea Neutrino Telescope – KM3NeTDeep Sea Neutrino Telescope – KM3NeT

J. Carr1, F. Cohen2, D. Dornic1, F. Jouvenot3, G. Maurin4 and C. Naumann4

for the KM3NeT consortium

1 CPPM – Centre de Physique des Particules de Marseille, CNRS/IN2P3, France2 IReS - Institut de Recherches Subatomiques, Strasbourg, France3 previously University of Liverpool, Oliver Lodge Laboratory – United Kingdom4 CEA Saclay – DSM/IRFU – Service de Physique des Particules, France

The case for a km3 neutrino telescopeThe case for a km3 neutrino telescopeMany known astrophysical objects such as AGNs, GRBs and SNRs, are expected to also produce TeV – PeV neutrinos by means of hadronic acceleration.Dark matter, accumulated in gravitational wells, is also expected to create neutrino signatures.In both cases, a detector volume of the order of cubic kilometres will be necessary.

To achieve this goal, the European KM3NeT consortium is currently in the preparatory phase for the construction of a cubic-kilometre neutrino telescope in the Mediterranean Sea. Similar to its South Pole counterpart IceCube, it will be able to survey a large part of the galactic plane and the extragalactic sky, while its location on the northern hemisphere will also allow it to directly view the galactic centre.

fixed: 127 strings

variable: string spacing

3 optical modules

= 10’’ PMTs

variable tilt

(9525 in total)

25 storeys,

variable spacing

Example: Hexagonal GeometryExample: Hexagonal Geometry

(m)

(m)

X X

Expected Performance (for NESSY Result)Expected Performance (for NESSY Result)

Hexagonal Configuration with

- 225 strings spaced by 100 m

- 25 storeys each, PMTs tilted 45°

Hexagonal Configuration with

- 225 strings spaced by 100 m

- 25 storeys each, PMTs tilted 45°

Towards a cubic kilometre detector in waterTowards a cubic kilometre detector in water

scale up – too expensive– too complicated– not easily scalable(readout bandwidth, power, ...)

new designdilute

absorption in water limits possible sensor spacing

sensitivity loss

– effective area 2 - 3 x IceCube

– muon angular resolution: 0.2° at 10 TeV

– expected sensitivity after 1 year of data taking:2.4 x 10-12 TeV-1 cm-2 s-1 for generic E-2 sources

– event rates for known TeV gamma sources (5 years):

test performance for various sets of geometry parameters

Expected fluxes require a detector volume of at least 1 km3…But: current sub-km3 designs cannot just be scaled up !

Perform Monte-Carlo design study to establish optimised geometry

New design optimised for:– sensitivity / cost– fast and easy installation– lifetime and stability

Source Name Detection ReconstructionRXJ1713.7-3946 3.4 / 17.3 1.4 / 8.1RXJ0852.0-4622 3.5 / 43.3 1.4 / 19.6

N / Natm with E > 1 TeV

Design Study with the “NESSY” toolsDesign Study with the “NESSY” tools

– simulation and reconstruction/analysis chain– detailed semi-analytic simulation of light generation and propagation– originally developed in Mathematica(1) framework

Fast and flexible approach to test a range of– physics parameters (absorption, scattering)– detector geometries– DAQ systems (thresholds, timing, etc)

Fast and flexible approach to test a range of– physics parameters (absorption, scattering)– detector geometries– DAQ systems (thresholds, timing, etc)

Distance between linesreconstruction

detector simulation

physics simulation

water parameters (abs, scattering)background (40K, biolum.)

detector geometry

front-end hardware

photomultiplier tubes

PMT configuration in the storey(number, distance, tilt)

effective area and angular resolution

optimal string distance = 100 m(balance between total volume and density)

optimum PMT configuration(for constant number of OMs): PMTs tilted by 45° (“standard”)

Nstrings=const.

(1)Wolfram Mathematica™ (www.wolfram.com)

exemplary results for hexagonal test geometry

exemplary results for hexagonal test geometry

1distance of PMT from string axis (standard=0.5 m)

(1)