xxiii international conference on neutrino physics and astrophysics 2008 christchurch, new zealand...
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XXIII International Conference on Neutrino Physics and Astrophysics 2008
Christchurch, New Zealand
Contacts: [email protected] [email protected]
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)