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

1. Distance between lines Detector Design Studies for a Cubic Kilometre Deep 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, France 2 IReS - Institut de Recherches Subatomiques, Strasbourg, France 3 previously University of Liverpool, Oliver Lodge Laboratory – United Kingdom 4 CEA Saclay – DSM/IRFU – Service de Physique des Particules, France The case for a km3 neutrino telescope Towards a cubic kilometre detector in water Expected  fluxes require a detector volume of at least 1 km3… But: current sub-km3 designs cannot just be scaled up ! Many 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. scale up • too expensive • too complicated • not easily scalable(readout bandwidth, power, ...) new design dilute • New design optimised for: • sensitivity / cost • fast and easy installation • lifetime and stability 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. absorption in water limits possible sensor spacing  sensitivity loss  Perform Monte-Carlo design study to establish optimised geometry Example: Hexagonal Geometry Design Study with the “NESSY” tools (m) • simulation and reconstruction/analysis chain • detailed semi-analytic simulation of light generation and propagation • originally developed in Mathematica(1) framework (1)Wolfram Mathematica™(www.wolfram.com) X X • Fast and flexible approach to test a range of • physics parameters (absorption, scattering) • detector geometries • DAQ systems (thresholds, timing, etc)  effective area and angular resolution 3 optical modules = 10’’ PMTs variable tilt (9525 in total) water parameters (abs, scattering) background (40K, biolum.) (m) physics simulation 25 storeys, variable spacing fixed: 127 stringsvariable: string spacing detector geometry  test performance for various sets of geometry parameters detector simulation photomultiplier tubes front-end hardware Expected Performance (for NESSY Result) reconstruction • Hexagonal Configuration with • 225 strings spaced by 100 m • 25 storeys each, PMTs tilted 45° Nstrings=const. • 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): PMT configuration in the storey(number, distance, tilt) optimal string distance = 100 m(balance between total volume and density) exemplary results for hexagonal test geometry (1) optimum PMT configuration(for constant number of OMs): PMTs tilted by 45° (“standard”) 1distance of PMT from string axis (standard=0.5 m)